Dissertations / Theses: 'Microalgae'

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Latil, de Ros Derek. "Microalgae as a new source of chitosans." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/402113.

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Chitosans are a family of linear polysaccharides generally obtained from the chemical deacetylation of chitin derived from crustacean shells that have been reported to have a wide range of bioactivities. However, the development of products taking advantage of these bioactivities has lagged behind expectations. The historic main reason is the poor reproducibility of the biological effects of chitosans due to a harsh chemical deacetylation process that impairs the structure of the polysaccharides inducing variability. Another reason is the immunologic responses that these polymers may produce in the presence of traces of crustacean proteins. It is therefore necessary to gather chitosans from other non-animal sources using a more environmentally friendly and reproducible process. Publications have commented that some microalgae species might contain chitin and even chitosan in their cell walls. Hence, in order to confirm these hypotheses, a screening method has been developed to detect each of these polymers specifically amongst the wide diversity of microalgae species of Greenaltech’s library. Thanks to this screening method, natural chitins and chitosans have been found in several genera. The methodology has been validated with the extraction and physicochemical characterization of chitins and chitosans from Chlorella, something that, to our knowledge, had never been done before. At the same time, the enzymatic deacetylation process behind the natural production of chitosan in Chlorella has been studied emphasizing the identification of active chitin deacetylases. Finally, as part of an exploratory biofunctional study of microalgal chitosans, the antimicrobial, wound healing and nanocapsule-forming properties have been analyzed.

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Carbonell, Chacón Sergi. "Microalgae cultivation in view of resource and energy recovery." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/669859.

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El rabdomiosarcoma (RMS) és el sarcoma de parts toves més comú en la infància i el seu origen rau en les cèl·lules embrionàries precursores del múscul esquelètic. Histològicament se subdivideix en dos tipus: l'embrionari (RMSe) i l'alveolar (RMSa), diferint en presentació clínica, pronòstic i resposta a la teràpia, i és el RMSa el que presenta pitjor pronòstic. El neuroblastoma (NBL) és el tumor sòlid extracranial més habitual en la infància i el tercer càncer pediàtric més recurrent. Representa un 15% de les morts pediàtriques per càncer. Hi ha diversos factors que determinen l'afectació del tumor: l'edat al moment del diagnòstic, l'estadi, alteracions cromosòmiques, la histologia i l'estat de l'oncogèn N-MYC. La supervivència tant del RMS com del NBL se situa al 70%, però aquesta es redueix fins al 30% en els casos de RMS amb malaltia metastàtica i recidiva, i fins al 20% en els casos de NBL d'alt risc. Aquests casos s'associen a la disseminació del tumor a causa de la metàstasi, quan els tractaments regulars no són efectius. És en aquest context on existeix la necessitat d'estudi dels factors que regulen el procés metastàtic per tal d'identificar noves dianes terapèutiques i així millorar la supervivència d'aquest grup de pacients. Les integrines són receptors transmembrana cel·lulars amb capacitat de transmetre senyal de l'exterior a l'interior de la cèl·lula i viceversa, que en modifiquen la plasticitat, adhesió i invasió cel·lular i estan implicades en processos patològics com la metàstasi. Anteriorment a aquesta tesi doctoral, el nostre grup d'investigació va suggerir per primera vegada la integrina α9β1 com una proteïna clau en la invasió de les cèl·lules de RMS. En aquesta tesi doctoral es demostra el paper de la integrina α9β1 en la invasió del RMS tant in vitro com in vivo mitjançant la seva inhibició genètica. Es mostra per primera vegada el paper del miR-7 i el miR-324 com a reguladors de la integrina α9β1. També es descriu com l'expressió de la integrina α9β1 en els tumors de RMS resulta en una tendència a una menor supervivència dels pacients, i posicionen la integrina α9β1 com a un marcador de mal pronòstic en el RMS. El caràcter invasiu de la integrina α9β1 es demostra també en el NBL, on l'expressió de la proteïna en les seves línies cel·lulars és molt elevada i contundent. S'ha dissenyat molècules blocadores contra la integrina α9β1 a partir d'un dels seus múltiples lligands, tot dirigint el treball cap a una recerca translacional per intentar cobrir les necessitats de la clínica en el tractament del RMS i el NBL. Els inhibidors seleccionats presenten efectes antiinvasius en les línies cel·lulars de RMS i NBL positives per la integrina α9β1. S'ha dut a terme un model murí de metàstasi de RMS amb l'administració dels dos inhibidors més prometedors. Un d'ells ha demostrat ser efectiu in vivo, en el qual s'ha observat un retard en l'aparició de metàstasi i una menor incidència de metàstasi comparat amb el grup control. En resum, en aquesta tesi doctoral es descriu el paper de la integrina α9β1 en el RMS i el NBL i es demostra el rol d'aquesta en la metàstasi. A més, es desenvolupa un nou inhibidor contra la integrina α9β1, que presenta un fort efecte antiinvasiu tant in vitro com in vivo. Així doncs, es proposa la integrina α9β1 com una nova diana terapèutica contra el procés metastàtic en el càncer pediàtric.
Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in childhood and it is derived from primitive mesenchyme that retained its capacity for skeletal muscle differentiation. Histologically, it can be divided into two main subtypes: embryonal rhabdomyosarcoma (RMSe) and alveolar rhabdomyosarcoma (RMSa), with differing in clinical presentation, prognosis and responses to therapy, with RMSa having the worst prognosis. Neuroblastoma (NBL) is the most common extracranial solid tumor in childhood and the third most recurrent pediatric cancer. It accounts for around 15% of all pediatric oncology deaths. Several factors determine tumor involvement: the age at the time of diagnosis, the stage, chromosomal disorders, histology and the state of the N-MYC oncogene. Survival rates for RMS and NBL are 70%, but fall to 30% in cases of metastatic RMS and recurrence, and to 20% in cases of high risk NBL. These cases are associated with the dissemination of the tumor due to metastasis, when regular treatments are not effective. It is in this context where there is a need to study the factors that regulate the metastatic process in order to identify new therapeutic targets and thus improve the survival of this group of patients. Integrins are cellular transmembrane receptors capable of transmitting signal from the outside to the inside of the cell and viceversa. They can modify plasticity, adhesion and cell invasion and are involved in pathological processes such as metastasis. Prior to this doctoral thesis, our research group suggested α9β1 integrin as a key protein in the invasion of RMS cells for the first time. In this work, we demonstrate the role of α9β1 integrin in invasion both in vitro and in vivo through its genetic inhibition. The role of miR-7 and miR-324 as regulators of the α9β1 integrin is shown for the first time. How the expression of α9β1 integrin in RMS tumors results in a tendency for poorer survival for patients is also described, and α9β1 integrin is positioned as a poor prognostic marker in the RMS. The invasiveness of α9β1 integrin is also demonstrated in the NBL, where there is high protein expression in its cell lines. Blocking molecules have been designed against α9β1 integrin from one of its multiple ligands, and work directed towards translational research in order to cover the clinical needs of the treatment of RMS and NBL. Selected inhibitors have antiinvasive effects on α9β1 integrin RMS and NBL cell lines. A murine metastases model of RMS has been performed with the administration of the two most promising inhibitors. One of these has been shown to be effective in vivo, with a delay in the appearance of metastasis and a lower incidence of metastasis compared to the control group. To sum up, this thesis describes the role of α9β1 integrin in the RMS and NBL and demonstrates its role in metastasis. In addition, a new inhibitor is developed against α9β1 integrin, which has a strong antiinvasive effect both in vitro and in vivo. Accordingly, α9β1 integrin is proposed as a new therapeutic target against the metastatic process in pediatric cancer.

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Haponska, Monika. "Biorefining of microalgae: from harvesting to biofuel production." Doctoral thesis, Universitat Rovira i Virgili, 2018. http://hdl.handle.net/10803/663366.

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Aquesta tesi es centra en la modernització del procés de bio-refinat de microalgues mitjançant tecnologia de membrana. El projecte busca l'optimització de: recol·lecció, ruptura cel·lular, fraccionament de carbohidrats, proteïnes i lípids i desenvolupament d'un reactor de membrana catalítica per a la transesterificació per obtenir biodièsel. La reducció de costos es pot aconseguir trobant solucions més barates i millors per a cada pas. En la primera etapa, es va realitzar la filtració utilitzant membranes polimèriques d'ABS de fabricació pròpia, així com altres disponibles comercialment, per comprovar el seu rendiment en la deshidratació de microalgues. Aquest estudi inclou la preparació i caracterització de membranes d'ABS usant diferents tècniques. A més, es va realitzar la comparació de dos mètodes de filtració, flux creuat i dinàmic per comparar la viabilitat de les membranes afectades per embrutiment. En la segona etapa, es va realitzar la deshidratació a escala pilot de dues espècies de microalgues, Chlorella sorokiniana i Dunaliella tertiolecta per sedimentació i filtració dinàmica. L'objectiu va ser reduir els costos de deshidratació de microalgues amb un cost menor al de centrifugació. bio-refinat de microalgues aigües avall. En la quarta etapa, es va realitzar la comparació de nous reactors de membrana catalítica i inert per a la producció de biodièsel amb òxid d'estronci com a catalitzador heterogeni. Els principals objectius van ser identificar un catalitzador adequat, triar la tècnica d'immobilització adequada, establir la membrana amb la mida de porus adequat i controlar la reacció i el procés de separació.microalgues amb diferents característiques de paret cel·lular. L'objectiu d'aquest treball va ser millorar el procés de bio-refinat de microalgues aigües avall. En la quarta etapa, es va realitzar la comparació de nous reactors de membrana catalítica i inert per a la producció de biodièsel amb òxid d'estronci com a catalitzador heterogeni. Els principals objectius van ser identificar un catalitzador adequat, triar la tècnica d'immobilització adequada, establir la membrana amb la mida de porus adequat i controlar la reacció i el procés de separació.
Esta tesis se centra en la modernización del proceso de biorefinado de microalgas mediante tecnología de membrana. El proyecto busca la optimización de: recolección, ruptura celular, fraccionamiento de carbohidratos, proteínas y lípidos y desarrollo de un reactor de membrana catalítica para la transesterificación para obtener biodiesel. La reducción de costos se puede lograr encontrando soluciones más baratas y mejores para cada paso. En la primera etapa, se realizó la filtración utilizando membranas poliméricas de ABS de fabricación propia, así como otras disponibles comercialmente, para comprobar su rendimiento en la deshidratación de microalgas. Este estudio incluye la preparación y caracterización de membranas de ABS usando diferentes técnicas. Además, se realizó la comparación de dos métodos de filtración, flujo cruzado y dinámico para comparar la viabilidad de las membranas afectadas por ensuciamiento. En la segunda etapa, se realizó la deshidratación a escala piloto de dos especies de microalgas, Chlorella sorokiniana y Dunaliella tertiolecta por sedimentación y filtración dinámica. El objetivo fue reducir los costos de deshidratación de microalgas con un costo menor al de centrifugación. En la tercera etapa, se estudió la disrupción celular y el fraccionamiento para la recuperación de lípidos, azúcares y proteínas usando explosión de vapor, flujo cruzado y filtración dinámica de membrana. Se probaron varias especies de microalgas con diferentes características de pared celular. El objetivo de este trabajo fue mejorar el proceso de biorrefinado de microalgas aguas abajo. En la cuarta etapa, se realizó la comparación de nuevos reactores de membrana catalítica e inerte para la producción de biodiesel con óxido de estroncio como catalizador heterogéneo. Los principales objetivos fueron identificar un catalizador adecuado, elegir la técnica de inmovilización adecuada, establecer la membrana con el tamaño de poro adecuado y controlar la reacción y el proceso de separación.
his thesis focuses on the modernization of the downstream process of microalgae biorefining by membrane technology. The project concerns the optimization of: harvesting, cell disruption, carbohydrates, proteins and lipids fractionation and development of catalytic membrane reactor for transesterification to obtain biodiesel. Cost reduction of the overall process can be achieved by finding cheaper solutions for each step. In the first stage the filtration using own-made ABS polymeric membranes as well as the commercially available ones was run to check their performance for microalgae dewatering. This study included ABS membranes preparation and characterization using different techniques. Also, the comparison of two filtration methods, cross-flow and dynamic was performed to compare the viability of membranes affected by a fouling and a cake formation. In a second stage, the pilot scale dewatering of two microalgae specie, Chlorella sorokiniana and Dunaliella tertiolecta by sedimentation followed by dynamic filtration was performed. The objective of the combined process was to reduce microalgae dewatering costs since sedimentation offers a very cheap operation and membrane filtration offers total rejection with high final concentrations at a lower cost than centrifugation. In a third stage cell disruption and fractionation for lipids, sugars and proteins recovery was studied. Acid-catalysedT

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Vidotti, Annamaria Dória Souza. "Cultivo heterotrófico axênico de Chlorella vulgaris = inibição por substrato = Axenic heterotrophic cultivation of Chlorella vulgaris : substrate inhibition." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266695.

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Orientador: Telma Teixeira Franco
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química.
Made available in DSpace on 2018-08-20T23:25:42Z (GMT). No. of bitstreams: 1 Vidotti_AnnamariaDoriaSouza_M.pdf: 2006384 bytes, checksum: cae5b036525c63c6b285732d6f067476 (MD5) Previous issue date: 2012
Resumo: Rotas heterotróficas a partir de microalgas apresentam ganhos significativos de produtividade em biomassa quando comparadas aos sistemas fotossintéticos convencionais, estando a glicose e o acetato entre as fontes de carbono mais comuns desse tipo de cultivo. Neste contexto, o objetivo do presente estudo foi desenvolver cultivos heterotróficos axênicos para a microalga Chlorella vulgaris, utilizando a glicose e o acetato de sódio como fontes de carbono exógeno, avaliando o efeito de inibição por substrato, bem como a modelagem dos perfis de crescimento de biomassa e consumo de substrato. A influência da concentração inicial de substrato na produção de biomassa pela C. vulgaris foi investigada, sendo obtidas cinéticas de crescimento do microrganismo submetido a concentrações iniciais de glicose entre 2 e 100 g.L-1, e de acetato de sódio, entre 2 e 20 g.L-1. Foi verificado que a concentração inicial de substrato influenciou significativamente o rendimento celular final, e que apesar dos dois substratos avaliados terem se mostrado fontes de carbono adequadas, a utilização de maiores concentrações iniciais, 100 g.L-1 e 20 g.L-1 de glicose e acetato de sódio, respectivamente, acarretaram na inibição do crescimento da C. vulgaris. Os modelos matemáticos testados representaram adequadamente a cinética de inibição, sendo que os resultados indicaram que a concentração ótima de glicose para o cultivo heterotrófico da C. vulgaris foi 5,8 ± 0,3 g.L-1 e de acetato de sódio foi 3,5 ± 0,2 g.L-1. Os resultados evidenciaram ainda que os procedimentos adotados no controle da contaminação foram efetivos para a manutenção da axenia dos cultivos. Pela comparação do desempenho cinético, foi constatada uma superioridade (maior que 50%) da glicose como substrato em comparação com o acetato de sódio. E no estudo de aumento de produtividade de biomassa para cultivos com acetato, foi obtido um aumento de 70% neste parâmetro com a batelada alimentada, e uma concentração final de biomassa 2,5 vezes maior do que a melhor concentração celular alcançada em shaker
Abstract: Heterotrophic microalgal routes show significant productivity gains in biomass when compared with the conventional photosynthetic systems, being glucose and acetate among the most common carbon sources such in this kind of cultivation. In this context the objective of this study was to develop axenic cultures for heterotrophic microalgae Chlorella vulgaris using glucose and sodium acetate as exogenous carbon sources, evaluating the effect of substrate inhibition, as well as the modeling of the biomass growth profiles and substrate consumption. The influence of the initial substrate concentration in the biomass production by C. vulgaris was investigated, being obtained kinetics growth of the microorganism subjected to initial glucose concentrations between 2 and 100 g/L-1, and sodium acetate between 2 and 20 g/L-1. It was found that the initial substrate concentration significantly affected the final cell yield and that although the two have been shown to be tested substrates carbon sources suitable, the use of larger initial concentrations of 100 and 20 g.L-1 of glucose and sodium acetate, respectively, resulted in inhibiting the growth of C. vulgaris. The mathematical models tested represented adequately the kinetics of inhibition, and the results indicated that the optimum concentration of glucose to heterotrophic cultivation of C. vulgaris is 5,8 ± 0,3 g.L-1 and for the sodium acetate this value is 3,5 ± 0,2 g.L-1. The results showed also that the procedures used in contamination control have been effective for the maintenance of the axenic of crops. By comparing the performance, kinetic superiority was observed (more than 50%) for the systems using glucose as substrate in comparison with the systems using sodium acetate. Finally, in the study of increasing of productivity of biomass for crops with acetate, was obtained a 70% increase in this parameter with the fed batch operation, and a final biomass concentration 2.5 times greater than the best cell concentration achieved in shake flasks
Mestrado
Desenvolvimento de Processos Químicos
Mestra em Engenharia Química

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Hom, Díaz Andrea. "Degradation of pharmaceutical compounds by microalgae: photobioreactor wastewater treatment, biomass harvesting and methanization." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/390962.

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Els contaminants emergents (ECs) són un ampli grup de compostos orgànics detectats en diversos compartiments ambientals que degut a la seva presència en el medi ambient i la seva difícil degradació han aixecat un gran interès en la comunitat científica. Tot i que la seva concentració normalment està compresa entre els ng/L i els μg/L, poden representar una amenaça per a la salut humana i el medi ambient ja que són excretats per la orina i els fems, ja sigui en forma de compost actiu o com a metabòlit, ja que no són completament assimilats. D’entre tots els emergents, els compostos disruptors endocrins (EDCs) i els principis actius dels fàrmacs (PhACs) generen especial preocupació. Està àmpliament acceptat que la seva principal font d’entrada al medi ambient és a través dels efluents de les plantes depuradores (WWTP), on els tractaments convencionals de llots actius no són capaços de degradar-ne la majoria, sent capaços d’arribar a les aigües superficials, subterrànies i, posteriorment, a l’aigua potable. Per tant, s’han de buscar tractaments alternatius. Un d’aquests tractaments podria ser l’ús de les microalgues aprofitant la seva capacitat pel tractament d’aigües residuals, eliminant els nutrients de l’aigua residual i la seva posterior conversió en biocombustibles. Aquesta tesi avalua diferents aspectes relacionats amb la degradació de contaminants emergents i tractament d’aigües amb microalgues. A més de l’estudi d’un dels principals colls d’ampolla dels sistemes de microalgues, la collita, que té l’avantatge de clarificar l’aigua residual tractada i concentrar la biomassa algal per a la seva conversió a biogàs. Tant, cultius purs com efluents de microalgues s’han considerat. Primerament, s’ha estudiat la degradació individual de dos compostos estrogènics. Aquests dos compostos estrogènics s’han introduït recentment a la llista de substàncies prioritàries de la directiva de l’aigua: 17α-etinileestradiol (EE2) i 17β- estradiol (E2). La seva degradació s’ha monitoritzat a partir dels cultius purs de Chlamydomonas reinhardtii i Pseudokirchneriella subcapitata a nivell de laboratori. Per tal d’obtenir més informació sobre els mecanismes de degradació s’ha fet la identificació dels productes de transformació. A més, la degradació d’una mescla de 10 fàrmacs (9 antibiòtics i un antidepressiu) s’ha avaluat en cultius purs de microalgues a escala laboratori. S’ha realitzat la identificació dels productes de transformació de tres PhACs seleccionats. Posteriorment, un dels antibiòtics, la ciprofloxacina, s’ha analitzat. Els seus mecanismes d’eliminació han estat estudiats en sistemes algals, tant en reactors a escala laboratori com en escala pilot. Per altra banda, s’ha dissenyat un fotobioreactor (PBR) d’algues tractant aigua residual urbana i en operació durant 6 mesos. S’ha monitoritzat el seu seguiment i s’han provat diferents condicions d’operació. A més, un cop a l’estat estacionari l’eliminació de PhACs s’ha estimat i s’ha caracteritzat la població microbiana. També s’ha estudiat l’eliminació del compost estrogènic E2 en el PBR. En aquesta tesi també es remarca la importància de la collita de microalgues. Tres tècniques de collita (i.e., sedimentació natural, coagulació-floculació i la tècnica innovadora de co-pel·letització utilitzant el fong Trametes versicolor) s’han aplicat en dos efluents reals de microalgues i a una suspensió pura de Chlamydomonas reinhardtii. Finalment, s’ha dut a terme la metanització de biomassa exhausta. Abans del procés de digestió anaeròbia, per tal de solubilitzar la paret cel·lular les algues han estat sotmeses a un pretractament enzimàtic. S’han provat enzims específics i no específics, així com l’efecte combinat utilitzant una mescla d’enzims. Aquest estudi es completa amb la valorització de biomassa fúngica que prové del tractament d’efluents.
Emerging contaminants (ECs) are a wide range of organic compounds detected in many environmental compartments that have raised an increasing interest in the scientific community due to their ubiquitous presence in the environment and their difficult degradation. Even though their environmental concentration is usually in the range of ng/L to μg/L, they still represent a threat to human health and environment since they are excreted with urine and faeces either as active substances or metabolites, because they are not completely assimilated. Among emerging contaminants, endocrine disrupting compounds (EDCs) and pharmaceutical active compounds (PhACs) are of major concern. It is widely accepted that the main source to the environment are the effluents of wastewater treatment plants (WWTP), where conventional activated sludge treatments are not able to degrade most of them being able to reach surface, groundwater and subsequently, drinking water. Therefore, alternative treatments should be found. One of those alternatives might be the use of microalgae by taking advantage of their capacity for wastewater treatment removing the nutrients contained in the wastewater and further microalgal biomass conversion into biofuels. The present thesis assesses different factors related to microalgal degradation of emerging contaminants and wastewater treatment. As well as the study of one of the major bottlenecks on microalgal systems, the harvesting, which has the advantage to clarify the treated wastewater and concentrate the microalgal biomass for further biogas production. Pure microalgal cultures and real microalgal effluents have been considered. First of all, individual degradation of two estrogenic compounds has been studied. The two estrogenic compounds evaluated have been recently incorporated in the priority substances in the Water Framework Directive: 17α-ethinylestradiol (EE2) and 17β- estradiol (E2). Their degradation by Chlamydomonas reinhardtii and Pseudokirchneriella subcapitata pure cultures at laboratory scale conditions has been monitored. To obtain further insights in the mechanism of degradation the transformation products have been identified. Moreover, the removal of a mixture of 10 PhACs (9 antibiotics and an antidepressant) has also been assessed in pure microalgal cultures at laboratory scale conditions. Transformation products from three chosen PhACs have been identified. One of the antibiotics, ciprofloxacin, was further evaluated. The removal mechanisms have been studied in real algal ponds in both, laboratory and pilot scale reactors. On the other hand, an algal photobioreactor (PBR) treating urban wastewater has been designed and operated during 6 months. Its performance has been monitored and different operating conditions have been tested. Furthermore, PhACs removal has been evaluated during the steady state and microbial diversity has been identified. The estrogenic compound E2 removal in the PBR has been studied. The importance of microalgal harvesting has been highlighted in the thesis. Three different harvesting techniques (i.e., natural sedimentation, coagulation-flocculation and the novel technique of co-pelletization using Trametes versicolor fungus) have been evaluated using two real microalgal effluents and a pure Chlamydomonas reinhardtii suspension. Finally, methanization of exhausted biomass has been conducted. Prior the anaerobic digestion process microalgal biomass has been submitted to an enzymatic pretreatment for its cell wall solubilisation. Specific and non-specific enzymes have been tested as well as the synergistic effects between an enzymatic mixture. The study is completed valorising fungal biomass coming from the treatment of effluents.

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Brain, Chelsea Marie. "Bioprocessing in microalgae." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3695.

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This thesis is a portfolio of three projects carried out with Scottish Bioenergy Ltd, in the area of microalgae biotechnology. The first small project saw the development of a rapid, simple and relatively low-cost technique based on UV absorbance for measurement of nitrate in two common freshwater and saltwater growth media. The test was successfully demonstrated in batches of Chlorella, measuring nitrate concentration as low as 40 μM and requiring only a 2 mL sample. The second large project investigated the use of a narrow spectrum Light Emitting Diode (LED) with a maximum wavelength (λmax) of 680 nm for the production of the high-value pigment phycocyanin in Arthrospira (Spirulina). The LEDs produced a substantial over 250 % increase in phycocyanin yield with no significant difference in growth rate in comparison to standard white LEDs, initially requiring an extended photoacclimation period. Although photobioreactor (PBR) systems incorporating the λmax 680 nm would require increased investment in capital and operational expenditure, particularly relating to increased LED cooling requirements, increased product yield and profitability makes a powerful case for switching to longer wavelength red LEDs. The third project was a feasibility study for the use of directed microevolution to generate a non-genetically modified copper-tolerant Arthrospira strain that may be used in a multi-process PBR system fed with distillery wastewater. Resistance 200-fold the typical optimal medium concentration was achieved. However, the extent of resistance was 3-fold lower than required and the length and unreliability made the process impractical for industrial use in generating resistant Arthrospira strains. The projects provided a methodology to assist the company in future research and development, knowledge on the feasibility of a strain development technique and identified an exciting new business opportunity for production of a high-value product in artificially illuminated PBR systems.

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Abida, Heni. "Characterization of lipid metabolism in the marine diatom Phaeodactylum tricornutum." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS231.

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L’océan domine la surface de notre planète et joue un rôle majeur dans la régulation de notre biosphère. Par exemple, les microorganismes photosynthétiques vivant dans l’océan produisent 50% de l’oxygène que nous respirons tous les ans, et une grande partie de notre alimentation et des ressources minérales en proviennent. En cette époque de crise écologique liée à l’accumulation anthropogénique de gaz à effet de serre dans l’atmosphère, il est impératif de développer des énergies plus durables que les carburants fossiles. Le biodiesel pourrait être une source de carburant viable et durable pour remplacer le pétrodiesel mais jusque-là, nos efforts visant à produire des lipides à base de microalgues se sont essentiellement concentrés sur des algues vertes. Dans cette thèse je propose des méthodes pour mieux caractériser une autre catégorie de microalgue : les diatomées. Les diatomées sont une composante importante du phytoplancton et contribuent 40% de la production marine de biomasse primaire. Les diatomées accumulent des lipides en réponse à la carence en nutriments, et même si elles semblent accumuler tout autant de lipides que les microalgues vertes, les voies métaboliques menant à l’accumulation de lipides sont encore peu connues.Dans cette thèse je décris notre caractérisation du glycerolipidome de la diatomée modèle Phaeodactylum tricornutum ainsi que notre étude du remodelage de lipides suite à la carence d’azote ou de phosphate. Des accessions de P. tricornutum isolées dans différentes régions de l’océan ont aussi été étudiées afin de comparer leurs réponses au stress nutritif. Nous avons trouvé que la réponse métabolique menant à l’accumulation de lipides en carence d’azote ou de phosphate est différente. En effet, la carence en azote semble déclencher le recyclage des galactoglycerolipides chloroplastiques ainsi qu’une augmentation de la biosynthèse de novo d’acides gras, alors que la carence en phosphate est plus sévère car nous avons observé une accumulation plus significative de triacylglycerols ainsi que la déplétion totale des phospholipides. De plus, nous avons observé des réponses au stress différentes entre les accessions de P. tricornutum, et en particulier concernant leur capacité à accumuler des lipides. Nous proposons l’hypothèse que ces différences sont liées à leur aptitude à recycler du carbone issu de molécules de stockage non lipidiques.Des approches génomiques ont permis de nombreuses avancées pour mieux comprendre le métabolisme des lipides de microalgues mais notre compréhension des voies de biosynthèse de lipides chez les diatomées est encore limitée. Il y a eu diverses tentatives de caractérisation de la réponse au stress de carence par approche transcriptomique mais l’étude de ces données est incomplète du fait de l’annotation insuffisante des gènes encodant les voies métaboliques pertinentes. Ainsi, dans cette thèse je décris nos tentatives d’annotation de gènes impliqués dans le métabolisme des lipides de P. tricornutum ainsi que les approches d’ingénierie génétique visant à mieux caractériser certains de ces gènes. J’ai également utilisé notre nouvelle annotation de gènes impliqués dans le métabolisme des lipides pour effectuer une étude comparative de plusieurs transcriptomes de P. tricornutum en conditions de carence trouvés dans la littérature. J’ai ainsi pu produire une liste de gènes potentiellement impliqués dans l’accumulation de lipides. Enfin, nous avons pu utiliser ces données pour aider l’interprétation de données génomiques et transcriptomiques issues de la diatomée oléagineuse Fistulifera solaris afin de mieux comprendre comment elle accumule des quantités importantes de lipides pour des applications dans le secteur des biotechnologies et des bioénergies
The ocean dominates the surface of our planet and plays a major role in regulating the biosphere. For example, the microscopic photosynthetic organisms living in the ocean provide 50% of the oxygen we breathe every year, and much of our food and mineral resources are extracted from the ocean. In a time of ecological crisis linked to the accumulation of anthropogenic greenhouse gases in the atmosphere, we must investigate more sustainable energies than fossil fuels. Much attention has been given to biodiesel but so far most efforts to efficiently produce triacylglycerols in microalgae have focused on green algae. In this thesis I propose approaches to better understand another type of microalgae that is significantly divergent from green lineages: diatoms. Diatoms are a major phylum of phytoplankton in the ocean and account for 40% of marine primary productivity. While diatoms appear to be at least as effective as green algae for producing lipids, the fatty acid and glycerolipid biosynthetic pathways leading to their production have not yet been well characterized. Therefore, I propose to better characterize these pathways in the model diatom Phaeodactylum tricornutum in order to help unlock the potential of diatoms for lipid-based biotechnological applications.In this thesis, I discuss our attempts to establish a reference for the glycerolipidome of P. tricornutum and of our assessment of the lipid remodeling and accumulation that occurs in response to nitrogen- and phosphorus-starvation. A range of accessions of P. tricornutum isolated from different parts of the ocean were also examined to compare their responses to nutrient deprivation. We found that the metabolic response leading to lipid accumulation in different nutrient-deprived conditions are distinct. Nitrogen-deprivation appears to trigger the recycling of chloroplastic galactoglycerolipids as well as a strong increase in de novo fatty acid synthesis while the response to phosphorus-deprivation was more severe as we observed a higher triacylglycerol pool and the complete depletion of phospholipids. Furthermore, we observed several differences among accessions of P. tricornutum regarding their ability to accumulate triacylglycerol in response to nutrient starvation and propose the hypothesis that these differences are linked to their ability to recycle intracellular carbon from non-lipid storage molecules.Genome-enabled approaches have also allowed significant steps towards elucidating the lipid metabolism of microalgae in the past decade, but our understanding of diatom metabolic pathways is still limited compared to that of other microalgae and higher plants. There have been several attempts to characterize the stress response in P. tricornutum by using transcriptomic approaches but this data is difficult to exploit to its full potential without a better annotation of genes encoding the relevant pathways. Therefore, in this thesis I discuss our attempts to annotate P. tricornutum lipid metabolism genes. Based on this annotation I have attempted to better characterize a selection of genes by genetic engineering and have pursued a comparative study of several published transcriptomes of P. tricornutum in nutrient deprived conditions to produce a list of candidate genes likely to be involved in triacylglycerol accumulation. Finally, we used this data to help interpret genome and transcriptome data of the newly sequenced oleaginous diatom Fistulifera solaris to help understand how it accumulates unusually high amounts of triacylglycerol for applications in the biotechnology and bioenergy industry

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Franco, Acosta Liliana Marcela. "Estudo de fontes de carbono orgânicos no cultivo heterotrófico da microalga Chlorella vulgaris." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266696.

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Orientador: Telma Teixeira Franco
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-21T17:18:31Z (GMT). No. of bitstreams: 1 FrancoAcosta_LilianaMarcela_M.pdf: 2933059 bytes, checksum: f29d16801f9dbfa85c5d787ef30251ad (MD5) Previous issue date: 2012
Resumo: Em cultivos heterotróficos, fontes orgânicas de carbono são utilizadas para fornecer energia e carbono ao micro-organismo. A glicose e uma das fontes mais utilizadas em cultivos de microalgas, gerando elevadas taxas de crescimento. Outras fontes como frutose, xilose, glicerol, sacarose, arabinose também podem ser utilizadas e a escolha entre essas fontes orgânicas e função principalmente das taxas de crescimento e do custo de aquisição. Visando elevadas produtividades e a redução do custo do cultivo heterotrófico da Chlorella vulgaris, diferentes fontes de carbono orgânico foram avaliadas (glicerol, sacarose, frutose e melaço de cana). Os máximos valores de concentração celular, pH e produtividade, foram para a sacarose hidrolisada na concentração inicial de 20 g.L-1 obtidos apos 122 horas de cultivo (5,3g.L-1; 8.80 e 0.040 g.L-1.h-1, respectivamente) e para o melaço de cana hidrolisado na concentração de 30 g.L-1 obtidos apos 60 horas de cultivo (3,92 g.L-1; 8,55 e 0,059 g.L-1.h-1, respectivamente). Glicerol, sacarose e frutose não foram consumidas pelas células. As melhores concentrações de sacarose hidrolisada (20 g.L-1) e melaço de cana hidrolisado (15 g.L-1) foram utilizados em fermentador de 3 L em regime de batelada alimentada, as velocidades especificas de crescimento para o melaço de cana aumentaram apos cada alimentação desde 0,0512 h-1 ate 0,0644 h-1. No entanto, para a sacarose hidrolisada a velocidade diminuiu de 0,0251 h-1 ate 0,0143 h-1. A concentração de lipídeos foi para a sacarose hidrolisada (23,77 %), e (10,72%) para o melaço de cana. Paralelamente, foram analisadas condições de estocagem da microalga Chlorella vulgaris, em ultrafreezer, empregando-se três criopreservantes: glicerol, metanol e DMSO, nas concentrações de 5 e 10%. Os resultados, apos 270 dias de estocagem, indicam que a microalga Chlorella vulgaris não sobrevive nas condições estabelecidas. No entanto, para uma estocagem de ate 180 dias pode-se empregar 10% de glicerol ou 10% de DMSO, necessitando somente 2 repiques da microalga apos o armazenamento para atingir sua velocidade normal de crescimento (0,2686 d-1), velocidade reportada para a microalga sem armazenamento no ultrafreezer
Abstract: In heterotrophic culture, sources of organic carbon are utilized to give energy and carbon to microorganisms. Glucose is one of the main sources utilized in micro algae culture which produces high growing rates. Another sources such as fructose, xylose, glycerol, saccharose and arabinosa, could also be utilized. The function of growing rates and acquisition costs is precisely to help us to choose the best one between these sources. With the idea of getting high productivities and to reduce costs of heterotrophic crops of Chlorella vulgaris, different sources of organic carbon where studied (glycerol, saccharose, fructose and sugar cane honeydew). The highest values of cellular concentration, pH and productivity, were obtain from hydrolyzed saccharose with an initial concentration of 20 g.L-1 after 122 hours of cultivation (5,3g.L-1; 8.80 y 0.040 g.L-1.h-1, respectively). Glycerol, saccharose y fructose were not consumed by the cells. The best concentrations of hydrolyzed saccharose (20 g.L-1) and hydrolyzed sugar cane honeydew (15 g.L-1) were utilized in 3 L fermenters in feed batch. The growing speed of the sugar cane honeydew increased after each feeding from 0,0512 h-1 to 0,0644 h-1. However, the growing speed for hydrolyzed saccharose decreased from 0,0251 h-1 to 0,0143 h-1. The concentration of fat acids for the hydrolyzed saccharose was 23,77 % and for the sugar cane honeydew was 10,72%. Storage conditions in ultrafreezer for the microalgae Chlorella vulgaris were studied at the same time using three different protectants such as glycerol, methanol and DMSO, all of them in 5% and 10% concentrations. The outcomes obtained after 270 days showed that the Chlorella vulgaris microalgae could not survive with the given conditions. However, 10% of glycerol or DMSO could be used in a 180-day storage and only 2 periodic transfer of the microalgae were needed after the storage to obtain the normal growing speed (0.2686 d- 1), which was the reported speed of the microalgae without ultrafreezer storage
Mestrado
Processos em Tecnologia Química
Mestra em Engenharia Química

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Gaignard, Clément. "Criblage, identification et caractérisations physico-chimiques d'exopolysaccharides de microalgues et Cyanobactéries." Thesis, Université Clermont Auvergne‎ (2017-2020), 2019. http://www.theses.fr/2019CLFAC067.

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Le principal objectif de cette thèse était d’améliorer les connaissances sur la capacité des microalgues et Cyanobactéries à produire des Exopolysaccharides (EPS). Le criblage effectué sur 166 souches de la Roscoff Culture Collection (RCC) a permis d’identifier 45 nouvelles souches potentiellement productrices d’EPS. Des études biochimiques par Chromatographie Echangeuse d’Anions Haute Performance couplée à un Détecteur Ampérométrique Pulsé (CEAHP-DAP), et par Chromatographie Phase Gaz couplée à de la Spectrométrie de Masse (CPG/SM) ont confirmé la nature polysaccharidique de 20 nouveaux polymères identifiés. Au cours de ce travail, des cultures en Photobioréacteur (PBR) 1,4 et 5 L ont été menées sur quelques souches et de caractériser au plus fin leur EPS (compositions biochimiques et caractéristiques physico-chimiques). Cela a conduit, en autre, à l’identification d’un hétéroxylane issu d’une microalgue Glossomastix. Cet EPS est constitué d’une chaîne principale de β-(1,3)- et β-(1,4)-d-Xylp substituée en positions O-2 et O-3 par diverses chaînes et/ou résidus terminaux tels que d-Xylp-(1→6)-d-Galp, d-Xylp-(1→4)-d-Galp, d-Xylp-(1→3)-d-Galp, Galp-(1⟶SF-Xylp-(1⟶Xylp-(1⟶Glcp-(1⟶.Enfin, des analyses statistiques réalisées sur 81 compositions en monosaccharides d’EPS de microalgues ont permis pour la première fois d’établir un lien entre la composition biochimique et l’appartenance phylogénétique des microalgues
The main objective of this thesis was to improve knowledge on the capacity of microalgae and Cyanobacteria to produce Exopolysaccharides (EPS). Screening carried out on 166 strains from the Roscoff Culture Collection (RCC) made it possible to identify 45 new potentially EPS producers. Biochemical studies using High Performance Anion Exchange Chromatography with a Pulsed Amperometric Detector (HPAEC-PAD), and Gas Chromatography with Mass Spectrometry (GC/MS) confirmed the polysaccharide nature of 20 new identified polymers. During this work, cultures in 1,4 and 5 L Photobioreactors (PBR) were performed on few strains in order to characterize at best their EPS (biochemical compositions and physicochemical characteristics). This word led, in addition, to the identification of a heteroxylan from the microalga Glossomastix. Its EPS consists of a main chain of β-(1,3)- and β-(1,4)-d-Xylp substituted in O-2 and O-3 positions by various chains and/or terminal residues such as d-Xylp-(1→6)-d-Galp, d-Xylp-(1→4)-d-Galp, d-Xylp-(1→3)-d-Galp, Galp-(1⟶SF-Xylp-(1⟶Xylp-(1⟶Glcp-(1⟶. Finally statistical analyzes carried out on 81 monosaccharide compositions of microalgae EPS made it possible for the first time to establish a link between biochemical composition and phylogenetic membership of microalgae

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Bonnefond, Hubert. "Amélioration de microalgues à vocation énergétique par pression de sélection continue." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066719/document.

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Le monde fait face à une crise environnementale sans précédent, induite par l’action toujours plus marquée de l’homme sur son milieu. Depuis le début de l’ère industrielle, l’utilisation massive des énergies fossiles, a provoqué un dérèglement climatique planétaire. Les microalgues offrent la possibilité de produire des biocarburants avec une empreinte carbone réduite mais nécessitent encore de nombreuses améliorations pour être économiquement viables. Une de ces améliorations, à l’instar de l’agriculture moderne, réside dans la sélection de souches plus productives. Dans ce travail de thèse, nous avons développé la sélection par pression continue, consistant à utiliser les processus de l’évolution pour faire émerger des populations d’intérêt.Une première voie explorée a consisté à utiliser la température, paramètre crucial de la croissance des microalgues, comme moteur de sélection. En soumettant une culture à des variations diurnes de température durant une année, nous sommes parvenus à adapter une souche de Tisochrysis lutea à une gamme de températures plus large, la rendant donc plus tolérante aux variations de ce paramètre.La seconde voie a cherché à accroitre la capacité de Cylindrotheca closterium à emmagasiner ou au contraire à mobiliser son azote intracellulaire, propriété physiologiquement liée à sa capacité à produire des lipides. En forçant une population de microalgues à s'adapter à des apports discontinus d'azote (succession d'états de satiété et de carence), il a été possible de sélectionner les individus les plus riches en lipides.Enfin, nous avons modifié l'appareil pigmentaire de Tisochrisis lutea pour la rendre plus transparente à la lumière. En soumettant cette espèce à une succession de chocs lumineux, il a été possible de sélectionner les individus possédant les antennes photosynthétiques les plus petites, permettant une productivité accrue
The world faces an unprecedented environmental crisis, led by the action always more marked with the man on its environment. From the beginning of the industrial era, the massive use of the fossil fuels, caused a global climatic disorder

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Rawdhan, Alanoud. "Unstructural studies of microalgae." Thesis, University of Newcastle upon Tyne, 2015. http://hdl.handle.net/10443/3140.

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The optimization of fixation protocols was undertaken for Dunaliella salina, Nannochloropsis oculata and Pseudostaurosira trainorii to investigate two different aspects of microalgal biology. The first was to evaluate the effects of the infochemical 2, 4-decadienal as a potential lipid inducer in two promising lipid-producing species, Dunaliella salina and Nannochloropsis oculata, for biofuel production. D. salina fixed well using 1% glutaraldehyde in 0.5 M cacodylate buffer prepared in F/2 medium followed by secondary fixation with 1% osmium tetroxide. N. oculata fixed better with combined osmium-glutaraldehyde prepared in sea water and sucrose. A stereological measuring technique was used to compare lipid volume fractions in D. salina cells treated with 0, 2.5, and 50 μM and N. oculata treated with 0, 1, 10, and 50 μM with the lipid volume fraction of naturally senescent (stationary) cultures. There were significant increases in the volume fractions of lipid bodies in both D. salina (0.72%) and N. oculata (3.4%) decadienal-treated cells. However, the volume fractions of lipid bodies of the stationary phase cells were 7.1% for D. salina and 28% for N. oculata. Therefore, decadienal would not be a suitable lipid inducer for a cost-effective biofuel plant. Moreover, cells treated with the highest concentration of decadienal showed signs of programmed cell death. This would affect biomass accumulation in the biofuel plant, thus further reducing cost effectiveness. The second investigation used the cell structure and gametogenesis of Pseudostaurosira trainorii to evaluate the cytoplasmic support for the molecular phylogeny of diatoms proposed by Medlin and Kaczmarska (2004) which divides diatoms into three clades that differ in their ultrastructure, where Clade 1 contains centric diatoms, Clade 2a centric bipolar and multipolar diatoms and Clade 2b pennate diatoms. P. trainorii is classified as araphid diatom which has a thread-like structure reported by Sato et al. (2011) that could resemble the flagella in centric diatoms. P. trainorii fixed better with combined osmium-glutaraldehyde prepared in sea water and sucrose, and it was found that its Golgi apparatus and auxospore were resemble those of Clade 2b, while the pyrenoid structure might represent a variation of the structures described for other members of Clade 2b. In addition, this study proved that the thread-like structures in P. trainorii were not flagella.

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Biller, Patrick. "Hydrothermal processing of microalgae." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/4687/.

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Microalgae are regarded as a promising biomass resource for the production of biofuels and chemicals which does not compete with food production. Microalgae contain large amounts of lipids and have faster growth rates than terrestrial biomass. One of the current technological bottlenecks of biofuels conversion is the economic extraction and processing of microalgae components. Due to their aquatic nature microalgae contain large amounts of water when harvested. Hydrothermal liquefaction (HTL) involves processing the algae as a slurry in hot compressed water, avoiding drying of the wet feedstock. This is a major energy benefit compared to dry microalgae processing methods. A detailed characterisation of the microalgae feedstocks investigated for the current work is provided. The main differences between marine, fresh water and cyanobacteria strains are presented. The microalgae strains are investigated for biochemical composition, proximate and ultimate analysis, thermo-gravimetrical analysis, pyrolysis GC-MS, metal content, pigment analysis and by scanning electron microscopy. The results from the characterisation work are employed throughout the thesis for mass balance calculations and investigation of reaction chemistry. HTL for bio-crude production is investigated both on laboratory batch systems and a continuous pilot scale facility. Processing at mild conditions results in mainly the lipids of microalgae being extracted resulting in a high quality bio-crude. Higher temperatures are shown to result in higher yields of bio-crude as carbohydrates and proteins increasingly contribute to bio-crude formation. This allows processing of low lipid containing microalgae which are associated with higher growth rates. Maximum bio-crude yields of around 50 wt.% can be achieved but can contain significant amounts of nitrogen and oxygen. A total of 11 microalgae strains is investigated leading to an average bio-crude yield of 34 %, a heating value of 36 MJ/kg, a nitrogen content of 4.7 wt.% and an oxygen content of 13.6 wt.%. The use of homogeneous and heterogeneous catalysts is investigated to increase bio-crude quality and yields. Model compounds of protein, lipid and carbohydrates are processed individually to shed light on the HTL behaviour of microalgae components and the reaction pathways involved in bio-crude formation. The effect of sodium carbonate and formic acid as homogeneous catalysts is investigated on various microalgae strains with changing biochemical composition and on model compounds separately. It is shown that biochemical components of microalgae behave additively in respect to bio-crude formation. The trends of bio-crude formation follow lipids>protein>carbohydrates. It is further shown that carbohydrates are best processed in alkali conditions while protein and lipids are best processed without the use of catalysts. The same effect is demonstrated for algae high in carbohydrates or proteins and lipids respectively. Heterogeneous catalysts are shown not to increase the bio-crude significantly but result in additional decarboxylation of the bio-crude to reduce the oxygen level by a further 10%. The process water composition from HTL is investigated for common nutrients required for algae cultivation. It is shown that nutrients are present in higher concentrations than comparable standard algae growth media. The process water also contains large amounts of organic carbon which is considered a loss, unavailable for bio-crude formation. Growth trials in dilutions of the process water to grow fresh algae demonstrate that growth is sustainable. The organic carbon in the process water is shown to act as a substrate for mixotrophic growth resulting in increased growth rates and carbon efficiency. For analysis of the algae obtained from small scale growth trials a new analysis technique for microalgae composition analysis is introduced. This involves Py-GC-MS of model compounds and comparisons to algae pyrolysis products. Promising results are presented, showing the feasibility of detecting protein, carbohydrate and lipid levels of microalgae directly from growth cultures. Additionally the methodology is expanded to detect phytochemical concentrations such as astaxanthin and chlorophyll a. An alternative to direct hydrothermal liquefaction involving removal of valuable compounds from microalgae by hydrothermal microwave processing (HMP) is investigated. HMP is shown to remove protein and large amounts of nutrients from the algae biomass which could be used as a source of nutrients for microalgae cultivation. The cells walls are shown to be disrupted, leading to increased recovery of lipids by solvent extraction while the lipids‟ degree of saturation is not affected. This allows effective extraction of high value poly-unsaturated fatty acids. The residue form HMP is processed using flash pyrolysis and HTL for bio-crude production. The results show that bio-crudes of increased quality are produced. The technique appears especially suitable for marine microalgae strains as the salt content acts as microwave absorbers, reducing energy consumption and increasing reaction rates. Overall, the experimental work shows that hydrothermal processing is a low energy intensive wet processing technique for microalgae to produce bio-fuels and chemicals.

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GUETTI, DUILIO. "Biodiesel production from microalgae." Doctoral thesis, Università Politecnica delle Marche, 2015. http://hdl.handle.net/11566/242930.

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Le microalghe rappresentano una risorsa naturale per la produzione di biocombustibili i quali si rendono oggigiorno necessari per garantire sostenibilità energetica al pianeta dato il diminuire delle risorse fossili. Tuttavia il costo alla pompa di 1 litro di “algaediesel” oggi sarebbe di oltre 2,5$. Pertanto la diminuzione del suo costo è primario per poter affermare una delle tecnologie rinnovabili più promettenti del secolo attuale: di fatti le microalghe sintetizzano CO2 tramite fotosintesi ed hanno tassi di crescita spaventosamente veloci se confrontati con le tradizionali colture terrestri. Lo sforzo scientifico è quello di poter intervenire efficientemente in tutte le fasi coinvolte nel processo: dalla selezione di nuovi ed interessanti ceppi microalgali fino alla ottimizzazione del profilo lipidico ottenibile con la loro crescita. In questo lavoro si è cercato di evidenziare questi aspetti cruciali quali l’importanza della produttività lipidica, la sua stabilità e la possibilità di integrazione tecnologica tramite l’uso di un mezzo di crescita costituito da un refluo zootecnico proprio perché il mezzo di crescita è una delle voci di costo più elevate. Gli esperimenti hanno mostrato che: nuovi ceppi oleaginosi di microalghe con %lipidi per DW (>20%) possono ancora essere scoperti ed ottimizzati nella crescita; che un processo di produzione di biodiesel non può prescindere da biomassa con produttività e profilo lipidico stabile durante la fase di raccolta e che un refluo zootecnico, può essere un ottimo substrato di crescita per un ceppo “dominante” di microalghe soprattutto se vengono aggiustate le sue condizioni di crescita. Infine si è proposto un metodo per efficiente l’attuale processo industriale di biodiesel tramite con un approccio multiobiettivo, il quale ha permesso un risparmio termico del 13%.
Microalgae represent a natural resource to produce third generation biodiesel which is going to be necessary due to the shortening of the fossil resources. However, the actual cost of one litre of "algaediesel" would be higher than 2.5$. Therefore, the reduction of the costs connected with its production is primary to be make feasible one of the most promising renewable technologies of the century. Microalgae synthesize CO2 through photosynthesis growing much faster than traditional crop. The research is nowadays focused on efficiently improve of all the steps involved in the process: from the selection of new and interesting algal strains to the optimization of lipid profile obtainable from their cultivation. In this work, we tried to highlight and analyse important threads such as lipid productivity, lipids stability and productivity during continuous culture and the opportunity of integrate the wastewater treatment with the needing of lower the price of the growing substrate. The experiments show that new oleaginous strains with % of lipids in DW higher than 20% are easily discoverable and they will need a complete investigation on the optimization of the growth. They also show that the biodiesel production process cannot be separated from biomass productivity and lipid profile stability during the harvest of the biomass. Moreover, we show how a wastewater can be an excellent growth substrate "dominant" microalgae strain which can grow with good performances in a waste lowering the money necessary for the cultivation. Finally, we proposed a method for efficiently optimize the thermal needing of a real biodiesel plant by a multi-objective approach which allow saving of 13% of the thermal requirement.

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Prioretti, Laura. "Sulfur metabolism in microalgae." Doctoral thesis, Università Politecnica delle Marche, 2015. http://hdl.handle.net/11566/243011.

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La concentrazione media di SO4 2- in oceano è 28-30 mmol L-1. Essa ha subito notevoli variazioni nel corso della storia della Terra e potrebbe aver facilitato la radiazione delle alghe della linea rossa (alghe con chl a+c quali diatomee, dinoflagellate e coccolitoforidi) a discapito di quelle della linea verde (alghe con chl a+b) e dei cianobatteri. È ancora da chiarire se gli enzimi responsabili dell’assimilazione del SO4 2- negli organismi fotosintetici abbiano svolto un ruolo nel controllare l’adattamento delle alghe alle variazioni di concentrazione del SO4 2-. In accordo con studi precedenti, la mia tesi dimostra che diverse specie algali possono acclimatarsi/adattarsi a diverse concentrazioni di SO4 2-. Anche se la disponibilità di SO4 2- non ha provocato cambiamenti drastici nella composizione cellulare, l’attività degli enzimi coinvolti nell’assimilazione riduttiva del SO4 2- è stata sensibilmente modificata, soprattutto quella dell’ATP solforilasi (ATPS), suggerendo che la disponibilità di SO4 2- sia un fattore importante nel controllo delle risposte intracellulari a breve termine mediate da induzione/inibizione delle attività enzimatiche. Lo studio delle sequenze di ATPS ha rivelato che contrariamente ad altri organismi, quelle algali hanno molti residui di cisteina. La posizione di alcuni di essi è conservata, sebbene vi sia una notevole differenza tra alghe eucariotiche e α-cianobatteri, e β-cianobatteri. Per verificare se l’ATPS potesse essere redox regolata in modo diverso in questi gruppi, l’attività dell’ATPS di sette specie è stata testata dopo trattamento con agenti riducenti (ditiotreitolo) o ossidanti (trans-4,5- diidrossi-1,2-ditiano) dei gruppi tiolici delle cisteine. Le cisteine dell’ATPS parzialmente purificata da Synechocystis sp. (β-cianobatteri) e T. pseudonana (eucarioti/α-cianobatteri) sono state poi identificate mediante spettrometria di massa dopo alchilazione dei gruppi sulfidrilici con iodoacetamide. I risultati mostrano che il numero e la posizione delle cisteine nelle ATPS algali sono fattori importanti per la regolazione della loro attività.
At present, the mean oceanic SO4 2- concentration is 28-30 mmol L-1. This nutrient underwent large variations during Earth history and may have influenced phytoplankton radiation by facilitating the expansion of algae of the red lineage (chl a+c algae like diatoms, dinoflagellates and coccolithophorids) at the expense of algae of the green algae (chl a+b algae) and cyanobacteria. Whether the enzymes that control SO4 2- assimilation in photosynthetic organisms have played a role in controlling algal adaptation to changes in SO4 2- concentration is however unclear. In agreement with previous studies, my thesis reveals that different algal species can modify their physiology to acclimate/adapt to different SO4 2- concentrations. Although SO4 2- availability did not elicit dramatic changes of cell internal composition, the activity of the enzymes involved in the reductive SO4 2- assimilation were appreciably modified, especially ATP sulfurylase (ATPS), suggesting that SO4 2- availability is an important factor in controlling short-term intracellular responses mediated by induction/inhibition of S-related enzymes. The study of ATPS sequences revealed that contrary to other organisms, algal ATPS has a high number of cysteine residues (cys). The position of some of these is conserved, but a notable difference exists between eukaryotic algae and α-cyanobacteria, and β-cyanobacteria. To test if ATPS may be redox regulated in different way in these groups, ATPS activity from seven species was tested after treatment with reducing (dithiothreitol) or oxidizing (trans-4,5-dihydroxy-1,2- dithiane) agents reacting with cys thiol groups. The cys of the partially purified ATPS from Synechocystis sp. (β-cyanobacteria) and T. pseudonana (eukaryotic/α-cyanobacteria) were then identified by mass spectrometry after sulfhydryl alkylation with 2-iodoacetamide. The results show that the number and position of cys in algal ATPS are important factors for the regulation of its activity.

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LIN, HONGMIN. "Sulfur Metabolism in Microalgae." Doctoral thesis, Università Politecnica delle Marche, 2018. http://hdl.handle.net/11566/259778.

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Gli organismi fotosintetici acquisiscono lo zolfo in forma di solfato e lo assimilano, in un processo riduttivo, come solfuro. L’amminoacido cisteina è il primo composto organico in cui lo zolfo viene incorporato al termine della via di assimilazione. Perché il solfato possa essere ridotto, deve prima essere attivato ad AdenosinFosfosolfato (APS). Questa reazione è catalizzata dall’enzima ATP-solforilasi, che nella gran parte delle alghe, eccetto dinoflagellate e -cianobatteri, e a differenza di tutti gli altri organismi, è soggetta a regolazione redox. Gli altri passaggi della via di assimilazione del solfato nelle alghe si ritiene siano simili a quelli che hanno luogo nelle piante. Una possibile ulteriore eccezione è rappresentata dal passaggio che porta alla sintesi della cisteina, che è catalizzata da due enzimi: la Serina Acetil Trasferasi (SAT) e la O-Acetil Serina (Tiol)Liasi (OAS-TL). Nelle piante, questi due enzimi formano un complesso, il Complesso della Cisteina Sintasi (CSC). Rispetto alla ATP-sulforilasi, ho cercato di verificare se la sua regolazione redox, in vivo, fosse mediata dallo stato redox del pool tilacoidale dei plastochinoni. I miei risultati indicano che non è così. L’utilizzo in vivo del DCMU, che blocca il trasferimento di elettroni dal PSII ai plastochinoni, infatti, non ha avuto alcuna influenza sull’attività della ATP solforilasi. Per quanto riguarda gli enzimi implicati nella sintesi della cisteina, l’analisi delle sequenze proteiche ha indicato che il dominio C terminale della SAT, che si ritiene sia responsabile dell’interazione con la OAs-TL, è molto simile in alghe e in piante. Tuttavia, la porzione N-terminale delle SAT algali, che è probabilmente implicata nelle interazioni tra monomeri della SAT, è diversa da quella delle piante. Questo fa ritenere che i CSC algali possano essere diversi da quelli delle piante. Per chiarire questo punto, ho purificato la OAS-TL di 7 specie algali di diversa tassonomia. Le OAS-TL algali sono risultate di diversa taglia, seppure sempre comprese tra 35 e 44 kDa. Tutte le proteine purificate sono risultate attive, anche se ho riscontrato differenze nell’attività specifica. L’attività, in quasi tutti i casi, era più alta quando l’enzima era saggiato in soluzioni più diluite, come peraltro avviene nelle piante. Questo è dovuto al fatto che la OAS-TL non è attiva quando associata alla SAT. E questa associazione è più probabile quando gli estratti proteici sono più concentrati. Per verificare dunque che le OAS-TL algali fossero implicate nella formazione di un CSC, ho analizzato la propensione di questi enzimi a complessare una SAT della pianta Arabidopsis thaliana (sovraespressa in E. coli). Per tutte le specie algali studiate, ho osservato la formazione di CSC, sebbene la forza della interazione tra SAT e OAS-TL variasse da specie a specie. I CSC sono stati purificati e la presenza di OAS-TL and SAT nei complessi nativi è stata confermata utilizzando anticorpi per entrambe le proteine. I CSC formati dalle OAS-TL algali erano notevolmente più grandi di quelli che si costituiscono nelle piante: i CSC algali avevano una massa di circa 600 kDa, dunque quasi doppia rispetto a quella dei CSC delle piante (320 kDa). Dato che i monomeri di alghe e piante non hanno masse molto diverse, questo fa ritenere che i CSC algali abbiano stechiometria diversa. Sulla base delle dimensioni del complesso e dei monomeri, ipotizzo che le CSC algali contengano due trimeri di SAT, con un dimero di OAS-TL per ogni monomero di SAT. Di non secondario interesse è il fatto che la propensione a formare CSC è apprezzabilmente maggiore nelle alghe verdi che nelle alghe della linea rossa. Questo suggerisce che nelle alghe della linea rossa ci sia una maggior proporzione di OAS-TL libere. Siccome la sintesi di cisteina è catalizzata solo dalle OAS-TL libere, questo porta a concludere che, in queste alghe, il flusso di S verso la cisteina sia maggiore. Ciò concorda con la maggior quota cellulare di S nelle alghe della linea rossa, rispetto a quelle della linea verde.
Sulfur is a fundamental element for all living organisms. It is acquired as sulfate, which is also the most abundant S form in the ocean, and is assimilated as sulfide, which is fixed in the S-amino acid cysteine. Sulfate assimilation thus requires its reduction to sulfide. For sulfate to be reduced, it needs to be activated to Adenosine PhosphoSulfate (APS). This reaction is catalyzed by ATP-Sulfurylase, which in eukaryotic algae and oceanic cyanobacteria, differently from all other organisms are subject to redox regulation. The other steps of the sulfate assimilation pathways are believed not to differ in algae, as compared to embryophytes. The only other step on which the lack of information leaves crucial open questions is the synthesis of cysteine. Cysteine synthesis is catalyzed by two enzymes, Serine Acetyl Transferase (SAT) and O-Acetyl Serine (Thiol) Lyase (OAS-TL), which in embryophytes form a complex, the Cysteine Synthase Complex (CSC). My thesis will focus on these two steps, with special attention to cysteine synthesis. With respect to ATP-sulfurylase, I have tried to assess if redox regulation is mediated by the redox state of the plastoquinon pool of thylakoids. My results suggest that this is not the case. The in vivo blockage of PQ reduction through the use of DCMU, a specific inhibitor of electron transfer from QA to QB, did not affect ATP-S activity. As for the enzymes of cysteine synthesis, my bioinformatic analysis showed that the phylogeny of SAT and OAS-TL are probably difficult to reconstruct due to the shuffling of these genes across groups with the possible contribution of horizontal gene transfer. By analyzing the protein sequences, I determined that the C-terminal domain of algal SAT, which is believed to be responsible for the interaction with OAS-TL, is very similar to that of embryophytes. This suggests that the interaction of SAT and OAS-TL occurs in algae as in embryophytes. However, the N-terminus of algal SAT, which is believed to be involved in the SAT/SAT interaction, is not equally conserved; therefore, differences in the assemblage of the CSC in algae are possible. In order to clarify this point, I purified OAS-TL from the freshwater cyanobacterium Synechocystis sp. PCC 6803, the green marine algae Tetraselmis suecica and Dunaliella tertiolecta, the green freshwater algae Chlamydomonas reinhardtii, the marine diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum, and from the marine dinoflagellate Amphidinium klebsii. These purified proteins showed some differences in mass, which was however always within the 35-44 kDa range. All the purified proteins were active, although specific activity differed among species. Interestingly, the activity, in most cases, was higher when the enzyme was more diluted; the enzyme is more active, as it also happens in embryophytes. For embryophytes, this has been interpreted as an indication that OAS-TL activity is modulated through protein-protein interaction. To verify the hypothesis that algae have CSC like embryophytes, I studied the ability of algae OAS-TL to form a complex with Arabidopsis thaliana SAT (overexpressed in E. coli). In all cases, a complex was formed, although the strength of the interaction between SAT and OAS-TL appeared to be different for different algal species. The presence of OAS-TL and SAT in the purified native complexes was confirmed by immunodetection of both proteins. The cysteine synthase complexes that were formed in these experiments were appreciably larger (approximately 600 kDa vs 320 kDa) than those of embryophytes. Further experiments will be required to ascertain the actual stoichiometry and structure of the algal CSC. However, based on the above observation, I propose that algal CSC is composed by two SAT trimers, with an OAS-TL dimer bound to each SAT monomer. This configuration would give a mass of about 600 kDa, compatible with the results obtained in our CSCS purification experiments. It is also noteworthy that the strength of the binding of algal OAS-TL to AtSAT5 was greater in green algae than in algae of the red lineage. This may be an indication of the fact that a greater proportion of OAS-TL is in the free form, in red-lineage algae, leading to a higher flux of S into cysteines. At this stage, this is only a hypothesis that requires further confirmation.

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LIMONGI, Antonina Rita. "“Green microalgae biohydrogen production”." Doctoral thesis, Università degli studi della Basilicata, 2022. http://hdl.handle.net/11563/154466.

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Nowadays, renewable energy is one of the most discussed issues by the international scientific community. The unrestrained use of fossil fuels has raised relevant questions about sustainability and effects on the environment. Hydrogen (H2) is considered a promising fuel due to its thermodynamical properties and CO2-free combustion. Nevertheless, environmental problems arise when H2 is produced using energy deriving from fossil sources: only “green hydrogen” identifies a production 100% based on renewable energy. Currently, several microorganisms are known for their ability to produce H2 as a metabolic feature. Regarding microalgae, most of the information comes from Chlamydomonas reinhardtii. In this green microalgae, two different photosynthetic production pathways and one fermentative-like metabolism have been described concerning transitory H2 production. To extend H2 production one requirement is the creation of a hypoxic environment. This occurs when photosynthetic activity slows down or if there is an increase in mitochondrial respiration rates. Moreover, the electron flow should be directed preferentially towards the H2 evolution enzyme, hydrogenase. Concerning physiological conditioning, one of the most promising strategies for H2 production is sulphur deprivation from cultivation medium: within three days, anaerobiosis develops under saturated light. Chlamydomonas has also represented an excellent example for the development of different molecular strategies, that allow to overcome some limitations and extend the H2 production. One of the limitations is related to sunlight saturation and dissipation that also affect H2 production. Mutants with the truncated light-harvesting antenna (tla) in the chloroplast are subject to fewer phenomena of photoinhibition and light saturation. Another limitation is linked to the competitive pathways that remove electrons from hydrogenase. Pgrl1 (protein gradient regulation like 1) mutant showed improved H2 production reducing this phenomenon. Another relevant issue is the oxygen sensitivity of the hydrogenase enzyme. The use of an O2-tolerant clostridial [FeFe]-hydrogenase, expressed in C. reinhardtii, showed better enzymatic rate, as the bacterial hydrogenase had a lower inactivation rate in aerobiosis. The work carried out over the past three years was aimed primarily at the isolation and characterization of microalgal species in the Basilicata region for the identification of new biohydrogen producers. Particular attention has been given to the search for strains with good growth rates and able to use different carbon sources. Secondly, the physiological behaviour of single and double mutants of Chlamydomonas was analyzed concerning H2 production by modulating light condition without resorting to stress application, such as sulphur deprivation. Freshwater samples collected in different villages of the Basilicata region were used to isolate microalgae with different morphologies. Microscopical observations and molecular identification made it possible to identify the genus of the isolated pure colonies. The growth of the various strains was followed by different methods: absorbance and chlorophyll content proved to be effective and fast for monitoring cell growth over the days. This made it possible to evaluate the growth rates of the species under examination. Various tests were carried out to detect the production of H2. Bioreactors were kept in dark, limited light (12 PAR) or sulfur deprivation (with intense light, 100 PAR). All the experiments considered different carbon source too. The levels of H2 gas produced were daily assessed by gas chromatography by taking a sample of the airspace in contact with the liquid culture in the airtight bioreactors. Desmodesmus sp. and Haematococcus sp. strains demonstrated production of H2 similar to wild type Chlamydomonas (5-10 ml/litre of culture). Furthermore, the same production occurred similarly using acetate or glucose. For Chlamydomonas mutants, the experiments were conducted in collaboration with the University of Córdoba (Spain). Investigated mutants were tla3, pgrl1, and one engineered with Clostridium bacterial hydrogenase (clostr) and the relative combinations tla3 + pgrl1 and clostr + pgrl1 from genetic cross. In this case, the wild type, single and double mutant strains were subjected to different lighting conditions (12, 50, 100, 450 PAR). In particular, the combination tla3 + pgrl proved to be the best as it is capable of producing H2 even at light intensities that are generally less tolerated, opening up new application scenarios. The single mutant Clostr showed instead a fast hydrogenase activity in a replete media also proportionally with the increase of light. In conclusion, the algae isolated during the PhD project have shown interesting implications for the production of H2 such as the metabolic versatility regarding the use of the different carbon sources. This leads to the need to carry out a more in-depth investigation of the mechanisms underlying the metabolism of these microalgae both from a physiological and a molecular point of view. Regarding single and double Chlamydomonas mutants, knowledge about their behaviour in different light conditions and the feasibility of H2 production has been expanded

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Mejías, Caballero Wilson Alexander. "Distribución actual y potencial de la microalga Didymosphenia geminata (Lyngbye) Schmidt en Chile." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/151417.

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Memoria para optar al Título Profesional de Ingeniero Forestal
Didymosphenia geminata (Didymo) es una microalga bentónica declarada plaga en el año 2013 por la Subsecretaria de Pesca. Esta tiene una amplia distribución en Chile, encontrándose desde la Región del Biobío hacia el sur del país. Las floraciones de esta especie, ocupan una alta proporción de la superficie de los ríos, alcanzando incluso un 100% de cobertura. Debido a los altos costos ambientales y económicos que provoca la presencia de la especie, es necesario determinar su potencial de expansión en el país y, de esta manera poder enfocar los esfuerzos para su control en las zonas más críticas. Es así como el objetivo de esta memoria fue estudiar la distribución actual y potencial de la microalga D. geminata en Chile. De este modo, mediante el uso de distintas variables bioclimáticas, ambientales y geográficas fue posible determinar la distribución potencial de la especie, encontrando que ésta tiene alta probabilidad de expandir su presencia por varias regiones del país. Este procedimiento se llevó a cabo con el algoritmo MAXENT, el cual fue escogido gracias a las buenas predicciones que ha presentado para esta especie con respecto a otros métodos. Por otro lado, se determinó que las variables que más incidencia tienen en la presencia de la especie son la variabilidad estacional, flujo acumulado y la precipitación del periodo más seco del año.
Didymosphenia geminata (Didymo) is a benthic microalgae, declared as a plague in 2013 by the Subsecretaria de Pesca. This species has a wide distribution in Chile, from Biobío Region towards the south of the country. The bloom of this species, occupy a high proportion of the rivers surface, reaching even a 100% of coverage. Due to the high environmental and economic costs caused by the presence of the species, it is necessary to determine its potential expansion in the country and, in this way, it being able to focus all efforts for controlling it in the most critical areas. Thus, the objective of this report was studying the current and potential distribution of D. geminata microalgae in Chile. Therefore, through the use of various bioclimatic, environmental and geographic variables it was possible to define the potential distribution of the species, concluding that it has a high probability of expanding its presence in several regions of the country. This procedure was carried out using the MAXENT algorithm, which was chosen due to the good predictions presented for this species with respect to others methods. On the other hand, it was determined that the variables which are most incidental in the presence of the species are seasonal variability, and the flow and precipitation accumulation in the driest quarter of the year.
Diciembre 2018

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Bonnefond, Hubert. "Amélioration de microalgues à vocation énergétique par pression de sélection continue." Electronic Thesis or Diss., Paris 6, 2015. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2015PA066719.pdf.

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Le monde fait face à une crise environnementale sans précédent, induite par l’action toujours plus marquée de l’homme sur son milieu. Depuis le début de l’ère industrielle, l’utilisation massive des énergies fossiles, a provoqué un dérèglement climatique planétaire. Les microalgues offrent la possibilité de produire des biocarburants avec une empreinte carbone réduite mais nécessitent encore de nombreuses améliorations pour être économiquement viables. Une de ces améliorations, à l’instar de l’agriculture moderne, réside dans la sélection de souches plus productives. Dans ce travail de thèse, nous avons développé la sélection par pression continue, consistant à utiliser les processus de l’évolution pour faire émerger des populations d’intérêt.Une première voie explorée a consisté à utiliser la température, paramètre crucial de la croissance des microalgues, comme moteur de sélection. En soumettant une culture à des variations diurnes de température durant une année, nous sommes parvenus à adapter une souche de Tisochrysis lutea à une gamme de températures plus large, la rendant donc plus tolérante aux variations de ce paramètre.La seconde voie a cherché à accroitre la capacité de Cylindrotheca closterium à emmagasiner ou au contraire à mobiliser son azote intracellulaire, propriété physiologiquement liée à sa capacité à produire des lipides. En forçant une population de microalgues à s'adapter à des apports discontinus d'azote (succession d'états de satiété et de carence), il a été possible de sélectionner les individus les plus riches en lipides.Enfin, nous avons modifié l'appareil pigmentaire de Tisochrisis lutea pour la rendre plus transparente à la lumière. En soumettant cette espèce à une succession de chocs lumineux, il a été possible de sélectionner les individus possédant les antennes photosynthétiques les plus petites, permettant une productivité accrue
The world faces an unprecedented environmental crisis, led by the action always more marked with the man on its environment. From the beginning of the industrial era, the massive use of the fossil fuels, caused a global climatic disorder

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Tudó, Casanova Àngels. "Contribution to the risk assessment of ciguatera poisoning in europe (the balearic and Canary Islands and Madeira archipelago)." Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/672490.

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Actualment, la intoxicació alimentaria de la ciguatera (CP) es considera una malaltia emergent a les zones temperades d'Europa. La present tesi contribueix a l'avaluació del risc d'intoxicació per ciguatera a les Illes Balears (Mediterrània Occidental), Illes Canàries i arxipèlag de Madeira (Macaronèsia, Atlàntic Est). El present estudi caracteritza la biodiversitat i la distribució geogràfica dels gèneres Gambierdiscus i Fukuyoa a les illes més importants de Balears i Canàries. A més, s'avalua la producció potencial de CTX de les espècies Gambierdiscus i Fukuyoa. El risc de CP també s'avalua mitjançant la detecció de ciguatoxines en peixos de les Illes Balears i de l'Arxipèlag de Madeira. Tot i que la CP no és present a les Illes Balears, com es de-mostrarà aquí, la ciguatera es troba en l'etapa en la qual les poblacions de microalgues estan produint toxines similars a CTX i ho estan fent des de fa alguns anys. A la Macaronèsia, les troballes recents sobre les espècies de Gambierdiscus i les ciguatoxines en els mariscs han demostrat que encara hi ha poc coneixement sobre el fenomen de la CP i els seus agents causants.
Actualmente, la intoxicación alimentaria de la ciguatera (CP) se considera una enfermedad emergente en las zonas tem-pladas de Europa. La presente tesis contribuye a la evaluación del riesgo de intoxicación por ciguatera en las Islas Baleares (Mediterráneo Occidental), Islas Canarias y Archipiélago de Madeira (Macaronensia, Atlántico Este). El presente estudio caracteriza la biodiversidad y la distribución geográfica de los gé-neros Gambierdiscus y Fukuyoa en las islas más importantes de Baleares y Canarias. Además, se evalúa la producción potencial de CTX de las especies Gambierdiscus y Fukuyoa. El riesgo de CP también se evalúa mediante la detección de ciguatoxinas en peces de las Islas Baleares y del Archipiélago de Madeira. Aun-que la CP no está presente en las Islas Baleares, como se demostrará aquí, la ciguatera se encuentra en la etapa en la que las poblaciones de microalgas están produciendo toxinas similares a CTX y lo están haciendo desde hace algunos años. En la Macaronesia, los hallazgos recientes sobre las especies de Gam-bierdiscus y las ciguatoxinas en los mariscos han demostrado que todavía hay poco conocimiento sobre el fenómeno de la CP y sus agentes causantes.
Currently, ciguatera poisoning (CP) is now considered to be an emerging disease in temperate areas of Europe. The present thesis is a contribution to the risk assessment of ciguatera poisoning in the Balearic Islands (West Mediterranean Sea), the Canary Islands and the Madeira Archipelago (Macaronesia, East Atlantic). The current study characterizes the biodiversity and the geographical distribution of the Gam-bierdiscus and Fukuyoa genera in the most important islands of the Balearic and Canary Islands. In addi-tion, the potential CTX production of Gambierdiscus and Fukuyoa species is evaluated. The risk of CP is also evaluated by the detection of the ciguatoxins in fish from the Balearic Islands and Madeira Archipe-lago. Even though CP is not present in the Balearic Islands, as will be demonstrated here, ciguatera is at the stage that populations of microalgae are producing CTX-like toxins and have been doing so for some years. In the Macaronesia, recent findings about Gambierdiscus species and ciguatoxins in seafood have shown that it is still little knowledge about CP phenomenon and their causative agents.

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Nurra, Claudia. "Separation processes in microalgae biorefining." Doctoral thesis, Universitat Rovira i Virgili, 2014. http://hdl.handle.net/10803/403367.

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Aquesta tesi se centra en el desenvolupament de nous enfocaments per a processos de separació en la producció de biodièsel a partir de microalgues mitjançant tecnologia de membranes. Entre totes les etapes implicades en el procés, aquesta tesi se centra en la investigació de la deshidratació de microalgues mitjançant l'ús de diverses tècniques de filtració de membrana i en la transesterificació mitjançant l'ús d'un reactor catalític de membrana. L'etapa de collita és una de les principals responsables del cost final del biodièsel de microalgues, i la reacció de transesterificació necessita la utilització de massa quantitat d'aigua i moltes etapes que fan que aquest procés sigui inviable econòmicament per a aquesta aplicació. Calen millores en aquest sentit, a partir de la investigació de mètodes i materials més barats per al primer procés a configuracions més simples per a l'últim. Per assolir aquests objectius s'han realitzat estudis específics per a aquesta aplicació en: (i) nous materials en la filtració per membrana, a partir de polímers ja coneguts (PSF, PAN), a partir de polímers generalment no emprats en la indústria de la membrana (ABS, PETG, CA de serradures); (ii) noves tecnologies en la deshidratació de les microalgues, com un sistema de filtració vibratòria de flux transversal; (iii) noves perspectives en la reacció de transesterificació, amb la utilització de catalitzador heterogeni immobilitzat en una membrana polimèrica. Finalment, la permeabilitat és el paràmetre més estudiat en la tecnologia de filtració per membrana per a l'avaluació dels fenòmens de embrutiment. Aquest paràmetre depèn de moltes variables i el seu estudi és particularment important quan s'utilitzen membranes sintetitzades amb característiques desconegudes. Per simplificar la seva obtenció s'ha dut a terme un estudi teòric sobre la predicció de permeabilitat de la membrana amb el desenvolupament d'un model pensat per membranes poroses.
Esta tesis se centra en el desarrollo de nuevos enfoques para procesos de separación en la producción de biodiesel a partir de microalgas mediante tecnología de membranas. Entre todas las etapas implicadas en el proceso, esta tesis se centra en la investigación de la deshidratación de microalgas mediante el uso de varias técnicas de filtración de membrana y en la transesterificación mediante el uso de un reactor catalítico de membrana. La etapa de cosecha es una de las principales responsables del coste final del biodiesel de microalgas, y la reacción de transesterificación necesita la utilización de demasiada cantidad de agua y muchas etapas que hacen que este proceso sea inviable para esta aplicación. Se necesitan mejoras en este sentido, a partir de la investigación de métodos y materiales más baratos para el primer proceso a configuraciones más simples para el último. Para alcanzar estos objetivos se han realizado estudios específicos para esta aplicación en: (i) nuevos materiales en la filtración por membrana, a partir de polímeros ya conocidos (PSf, PAN) a polímeros generalmente no empleados en la industria de la membrana (ABS, PETG, CA de serrín); (ii) nuevas tecnologías en la deshidratación de las microalgas, como sistema de filtración vibratoria de flujo transversal; (iii) nuevas perspectivas en la reacción de transesterificación, con la utilización de catalizador heterogéneo inmovilizado en una membrana polimérica. Por último, la permeabilidad es el parámetro más estudiado en la tecnología de filtración por membrana para la evaluación de los fenómenos de ensuciamiento. Este parámetro depende de muchas variables y su estudio es particularmente importante cuando se utilizan membranas sintetizadas con características desconocidas. Para simplificar su obtención un estudio teórico final se ha llevado a cabo en la predicción de permeabilidad de la membrana con el desarrollo de un modelo pensado para membranas porosas.
This thesis focuses on the development of new approaches for separation processes in biodiesel production from microalgae by membrane technology. Biodiesel production from microalgae is a theme being developed in the last years that still need more investigation in order to reduce its costs. Among all steps involved in the process this thesis focuses the investigation of the microalgae dewatering by using several membrane filtration techniques and on transesterification by using a catalytic membrane reactor. Harvesting step is one of the major responsible of the final cost of microalgae biodiesel, and transesterification reaction needs the utilisation of too much quantity of water and many stages that make it unfeasible for this application. Enhancements are needed in this sense, starting from the research of cheaper methods and materials for the first process to simpler configurations for the latter one. Considerable attention has been dedicated to the complete understanding of membrane filtration technology in this application from the laboratory to the pilot plant scale. To reach these goals specific studies have been performed for this application on: (i) new materials in membrane filtration, from polymers already known (PSf, PAN) to polymers usually not employed in membrane industry (ABS, PETg, sawdust CA); (ii) new technologies in microalgae dewatering, as vibrating cross-flow filtration system; (iii) new perspectives in the transesterification reaction, with the utilization of heterogeneous catalyst immobilized on a membrane. Finally, permeability is the most studied parameter in membrane filtration technology for the evaluation of fouling phenomena. This parameter depends from many variables and its study is particularly important when synthesized membranes with unknown characteristics are used. To simplify its attainment a final theoretical study has been carried out on membrane permeability prediction by the development of a model conceived for porous membranes.

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21

Kaloudis, Dimitrios. "Improving microalgae for biofuel production." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665443.

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Microalgae are a diverse group of oxygenic photosynthetic microorganisms which show great promise as a source of biofuel. However, significant challenges still remain before microalgae can be considered a viable source of biofuel. The main current challenges are nutrient sourcing and recycling as well as downstream processing. The algal cell wall and especially the presence of an algaenan cell wall in some Chlorophyte algae could be an important variable in determining downstream processing costs but not much comparative research has been done to elucidate this. The first part of the present study focuses on the recently isolated alga Pseudochoricystis ellipsoidea (Trebouxiophyceae) and its improvement and assessment for biofuel production. Random mutagenesis and FACS screening protocols were developed for the isolation of pigment and cell wall mutants but despite considerable efforts no suitable mutants could be identified in the first half of this project. Two 500 L raceway ponds as well as an algal growth room and bubble column bioreactors were set up to facilitate algal research at the University of Bath and assess the performance of P. ellipsoidea in realistic culture conditions. P. ellipsoidea showed a maximum growth of 1.53 divisions day-1 in semi-open raceway ponds, resistance to contamination and a 30% lipid content, making it particularly suitable for raceway pond cultures. In the second part of this project six species of Chlorophyte (“green”) algae, three of which produced algaenan, were compared for suitability to growth in anaerobic digestate and municipal wastewater as well as cell wall strength, permeability and suitability to hydrothermal liquefaction. We found that anaerobic digestate was a good medium for the growth of all species independently of autoclaving and that non-autoclaved wastewater was a very challenging medium. Algaenan production did not affect cell disruption by ultrasonication but growth stage and cell wall thickness did. Lipid extraction kinetics by chloroform/methanol were greatly affected by algaenan, meaning that this material is relatively impermeable to organic solvents. Cell wall thickness, cell volume and lipid content also had an effect on lipid extraction kinetics but this was only measurable after 180 minutes of extraction. 8 Hydrothermal liquefaction showed high solid and low oil yields, very low sulphur (≤0.1 %) as well as a 1.1 % -1.8 % nitrogen content which is significantly lower than most algal HTL studies to date. This suggests that stationary stage algae are more difficult to process but give a cleaner biocrude and reduce the loss of nitrogen through incorporation in the oil. Significant opportunities for optimisation still exist in the HTL process.

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22

Roberts, Keiron. "Anaerobic digestion of marine microalgae." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/388117/.

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Anaerobic digestion is a simple and energetically efficient way in comparison to some other biofuel methods of producing renewable energy from a range of biomass types. Although digestion of micro-algal biomass was first suggested in the 1950s, only a few studies have been conducted for assessment of its performance. This work assessed the potential for energy recovery from microalgae via anaerobic digestion for both freshwater and marine species. This research screened seven laboratory-grown marine and freshwater microalgal species (Nannochloropsis. oculata, Thalassiosira . pseudonana, Dunaliella. salina, Rhododomas sp, Isochrysis. galbana, Chlorella. vulgaris and Scenedesmus sp) and two samples from large-scale cultivation systems for their suitability as a substrate for anaerobic digestion. Biochemical methane production and a theoretical maximum growth yield of each species were employed to offer a means of comparing methane productivity per unit of cultivation under standard conditions. The data generated were useful in determining suitable species to culture and digest under continuous operation. A review of the literature highlighted a gap in the knowledge for the continuous digestion of different marine micro-algal species, as well as the potential inhibitory effect of high salinities on the anaerobic digestion process to non-acclimatised systems run under continuous operation. Addition of total salt ≥ 10g L-1 caused reactor failure, supporting the findings of the literature review. It was possible, however, to gradually adapt the inoculum to marine concentrations of chloride salts (31.1 g L-1) with <7% difference in specific methane production of controls. Addition of sulphate showed competition between methanogens and sulphate-reducing bacteria with further minor losses in methane yield. There was up to 60% reduction in SMP for the highest sulphate loaded reactors, however, the population successfully adapted to sulphate concentrations above those typically found in seawater and showed gaseous H2S productivity in proportion to the applied sulphate load. This suggests that the effects of marine concentrations of chloride and sulphate salts can be overcome by a gradual acclimatisation. The selected algal species I. galbana and D. salina were continuously cultivated in a photobioreactor under low and high sulphate media and continuously digested using the salt adapted inoculum. The specific methane production for I. galbana and D. salina was 0.19 and 0.23 L CH4 g-1 VS, with a VS destruction of 32% and 50% respectively. Addition of a high SO4 grown D. salina as a feed resulted in a reduction of SMP to 0.19 L CH4 g-1 VS with an increase in H2S production. Loses in total solids and sulphur were observed under continuous study due to oxidation of H2S and struvite precipitation within the reactors, which was not observed under batch analysis. This highlights the importance in conducting continuous studies over batch, as these effects can be overlooked.

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23

Chalivendra, Saikumar. "Bioremediation of Wastewater Using Microalgae." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1418994496.

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24

Tijjani-Oshungboye, Kubura. "Microalgae biomass as fermentation feedstock." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1006168.

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The search for alternative energy is as a result of pollution generated by the utilization of fossil fuel. Bearing in mind the increase in demand which exceeds supply, alternative energy must reduce the carbon foot print in order to relieve use of fossil fuels. Biogas generation from wastes is an old technology that has been in existence for decades. This same concept was behind the development of the integrated algae ponding system (IAPS), where the use of microalgae biomass is adopted for waste water treatment and, anaerobic digestion which is a component of the IAPS, simultaneously generates biogas. The biogas from the IAPS was quantified in order to evaluate efficiency of the system and the anaerobic fermentation pit was also simulated in the laboratory to optimize biogas production using microalgae as co-fermentation feedstock. Microalgae biomass was evaluated as potential feedstock for ethanol fermentation and the use of biogas was investigated as an alternative transportation fuel. In an IAPS substantial biomass is produced on an annual basis. For effective treatment of waste water and efficient nutrient removal continuous harvest of the biomass is required. In the present study, water treatment efficiency of the EBRU IAPS was determined by carrying out a series of tests to investigate the decline in nutrient content from port of influent entry to effluent discharge. There was more than a 60% reduction in nutrient content with a concomitant increase in biomass and growth rate of 0.25 g/L . Biogas generated from the IAPS was quantified using a flow meter and the composition determined by gas chromatography. Methane which is the principal constituent of biogas was 75% (±SD, n=IO) and 2.34 m³.d⁻¹ was measured as biogas yield from the EBRU IAPS. The study also investigated the use of the excess microalgae biomass as a fermentation feedstock for ethanol production and as a co-substrate in order to increase biogas yield from the system. Positive results were achieved for ethanol production from microalgae although yield was generally low. About 385 mg.⁻¹ of ethanol was recovered when glucose was used as substrate, where as only 115 mg.⁻¹ of ethanol was recovered with microalgae as substrate. Suitability of microalgae as feedstock for ethanol generation and biogas generation was determined by characterisation which involved estimation of the carbohydrate, protein and lipid content, and analysis of the C, H, 0, Nand S content. Laboratory fed batch reactors simulated the anaerobic digestion process in order to study the effect of microalgae biomass as co-substrate for biogas generation. The fermenters were inoculated with an active consortium obtained from the Makana municipal waste water works and microbial studies were carried to confirm the presence of the anaerobic consortium. Different pre-treatments (concentrated, rupturing and freeze-drying) were used to disrupt the microalgae prior to introduction into fermenters in a ratio of 3: I. COD, TC, TOC, SO₄⁻² and TN analyses were carried out to monitor nutrient depletion in the system, and biogas generated by the system was quantified by volumetric analysis and the gas composition determined. Statistical analysis (ANOVA) was used to test for significant difference pre and post addition of microalgae. In the most effective fermenter, biogas production was at an average of 394 ml.d·' and CH₄ ratio in the biogas increased by over a 100%. Theoretical methane potential of the IAPS and the Makana municipal waste water works treating 5 ML.d⁻¹ of domestic waste was determined using the empirical formula of waste water and shown to yield 1,037,342.40 m³/yr. The projected biogas yield from this system was used to evaluate its potential use as transportation fuel. In total, 198,673 .55 m³ of biogas was estimated to be required to fuel the Rhodes University's fleet of vehicles, with a residual biogas stream of 838,668.85 m³. It was also demonstrated in the present study that renewable energy sourced from biomass has the potential of supplanting the use of fossil fuel resulting in less pollution leading to a cleaner and healthier environment.

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Sorigue, Damien. "Biosynthèse d'hydrocarbures dérivés des acides gras chez les microalgues." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4084.

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Les alcanes et les alcènes sont des hydrocarbures non cycliques important dans l’industrie. Ils sont synthétisés à partir d'acides gras par une grande variété d’organismes mais les connaissances à ce sujet sont très limitées chez les microalgues. Le but de ces travaux était donc de rechercher la présence d’alcanes ou d’alcènes dans diverses microalgues modèles, et d’essayer d’identifier la ou les enzymes responsables de la synthèse de ces composés. Nous avons mis en évidence la présence d’hydrocarbures linéaires en C15-C17 chez les microalgues Chlorella et Chlamydomonas. Ces composés étaient synthétisés uniquement en présence de lumière. L’absence dans le génome de ces microalgues d’homologues de gènes codant pour des enzymes connues de synthèse d’alcanes/alcènes a permis de conclure à la présence d’un nouveau système de synthèse d’hydrocarbures. Des purifications enzymatique et des analyses protéomique ont permis d’identifier une enzyme candidate qui exprimée chezE. coli est suffisante à la synthèse d’hydrocarbures. L'étude de cette enzyme révella qu'il s'agissait d'une photoenzyme utilisant l'énergie des photons bleue pour décarboxyler les acides grass en alca(e)ne. La structure de cette photoenzyme montre la présence un tunnel hydrophobe contenant l’acide gras et le cofacteur FAD. Cette nouvelle enzyme nommée « alcane photosynthase » amène de nombreuses question: qu'elle est la fonction des hydrocarbures chez ces microorganismes? Quel est le mécanisme catalytique de l’alcane photosynthase? Enfin, elle offre de nouvelles possibilités pour la production de biocarburants utilisant directement l’énergie solaire
Alkanes and alkenes are important in industry. Alkanes and alkenes are synthesized from fatty acids by a variety of organisms, such as plants and insects. However, the presence in microalgae of enzymes converting fatty acids into hydrocarbons has been poorly studied. The aim of this work was to investigate the presence of alkanes and alkenes in various microalgae models, and try to identify the enzymes responsible for the synthesis of these compounds.We have first demonstrated the presence of linear hydrocarbons C15-C17 in microalgae Chlorella and Chlamydomonas. Then we have shown that the main hydrocarbon formed in Chlorella and Chlamydomonas was derived from cis-vaccenic acid and was synthesized only in the presence of light. Absence of homologues of genes coding for known alkane/alkene biosynthetic enzymes in the genome of Chlorella and Chlamydomonas indicate the presence of an unknown pathway. Enzymatic purification and proteomic analysis allowed to identify a candidate enzyme which, expressed in E. coli lead to the formation of hydrocarbons with variable chain lengths, thus demonstrating that it was really an synthase alkane. Characterization showed that the enzyme was a photoenzyme, which used blue light to catalyse the decarboxylation of fatty acid to an alka(e)ne. The three-dimensional structure of this enzyme revealed a hydrophobic tunnel containing the fatty acid and the FAD cofactor

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26

Silveira, Carlos Alberto da. "Modelagem e simulação de reator de cultivo de microalgas tipo \"open pond\"." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-16062016-102640/.

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Mudança climática é um processo global, real e inequívoco. Para sua mitigação, a substituição de combustíveis fósseis por energias renováveis está sendo cada vez mais empregada. Devido à rápida velocidade de crescimento das microalgas, seu cultivo é visto como uma das alternativas mais promissoras para a produção de biocombustíveis. No presente trabalho, foi elaborado um modelo matemático fenomenológico que descreve o crescimento da microalga Chlorella vulgaris. Este modelo foi validado através de experimentos realizados em um reator piloto com capacidade de 1000 L tipo \"open pond\" (reator de raias) aberto ao ambiente, em condições não-axênicas. A variação de concentração devida à evaporação e/ou adição de água foi levada em conta no modelo. O modelo matemático desenvolvido, contendo dois parâmetros ajustáveis, descreve a variação da concentração de biomassa em função do tempo sob condições variáveis de luminosidade e temperatura. Os parâmetros ajustáveis são q (constante para conversão de intensidade luminosa em crescimento fotossintético, em klux-1 min-1) e Imax (limite máximo de intensidade luminosa, em klux). Previamente ao projeto do reator, foram realizados experimentos em reator de laboratório (utilizando a metodologia Taguchi) com o objetivo de determinar quais os fatores mais críticos para o crescimento da espécie de microalga selecionada e que, por isso, deveriam ser controlados com maior precisão. Além disso, foi analisada teoricamente a relevância da consideração do transporte de massa de CO2 no processo. Como este transporte é muito mais lento, a resistência controladora do processo é o crescimento fotossintético. Após a construção do reator piloto, foram realizados dois experimentos preliminares (os quais serviram para aperfeiçoar o aparato e o procedimento experimental) e três experimentos definitivos, registrando-se dados ambientais (temperatura, intensidade luminosa e pH) e de concentração ao longo do tempo. Utilizando os dados de temperatura e luminosidade em função do tempo como entrada, os parâmetros q e Imax otimizados foram ajustados às curvas de concentração versus tempo de cada experimento. Para tal foram desenvolvidos programas de integração de equações diferenciais e de otimização escritos em ambiente Scilab®. Verificou-se que, apesar da variabilidade devida às condições ambientais dos experimentos, obteve-se boa aderência dos dados simulados aos experimentais. Uma análise estatística dos parâmetros q e Imax calculados em cada experimento forneceu coeficientes de variação para estes parâmetros de 17 % e 5 %, respectivamente. Concluiu-se, portanto, que o modelo matemático desenvolvido neste trabalho pode ser empregado para prever o desempenho de um reator de raias em condições ambientais variáveis, bastando para isto o ajuste de dois parâmetros.
Mudança climática é um processo global, real e inequívoco. Para sua mitigação, a substituição de combustíveis fósseis por energias renováveis está sendo cada vez mais empregada. Devido à rápida velocidade de crescimento das microalgas, seu cultivo é visto como uma das alternativas mais promissoras para a produção de biocombustíveis. No presente trabalho, foi elaborado um modelo matemático fenomenológico que descreve o crescimento da microalga Chlorella vulgaris. Este modelo foi validado através de experimentos realizados em um reator piloto com capacidade de 1000 L tipo \"open pond\" (reator de raias) aberto ao ambiente, em condições não-axênicas. A variação de concentração devida à evaporação e/ou adição de água foi levada em conta no modelo. O modelo matemático desenvolvido, contendo dois parâmetros ajustáveis, descreve a variação da concentração de biomassa em função do tempo sob condições variáveis de luminosidade e temperatura. Os parâmetros ajustáveis são q (constante para conversão de intensidade luminosa em crescimento fotossintético, em klux-1 min-1) e Imax (limite máximo de intensidade luminosa, em klux). Previamente ao projeto do reator, foram realizados experimentos em reator de laboratório (utilizando a metodologia Taguchi) com o objetivo de determinar quais os fatores mais críticos para o crescimento da espécie de microalga selecionada e que, por isso, deveriam ser controlados com maior precisão. Além disso, foi analisada teoricamente a relevância da consideração do transporte de massa de CO2 no processo. Como este transporte é muito mais lento, a resistência controladora do processo é o crescimento fotossintético. Após a construção do reator piloto, foram realizados dois experimentos preliminares (os quais serviram para aperfeiçoar o aparato e o procedimento experimental) e três experimentos definitivos, registrando-se dados ambientais (temperatura, intensidade luminosa e pH) e de concentração ao longo do tempo. Utilizando os dados de temperatura e luminosidade em função do tempo como entrada, os parâmetros q e Imax otimizados foram ajustados às curvas de concentração versus tempo de cada experimento. Para tal foram desenvolvidos programas de integração de equações diferenciais e de otimização escritos em ambiente Scilab®. Verificou-se que, apesar da variabilidade devida às condições ambientais dos experimentos, obteve-se boa aderência dos dados simulados aos experimentais. Uma análise estatística dos parâmetros q e Imax calculados em cada experimento forneceu coeficientes de variação para estes parâmetros de 17 % e 5 %, respectivamente. Concluiu-se, portanto, que o modelo matemático desenvolvido neste trabalho pode ser empregado para prever o desempenho de um reator de raias em condições ambientais variáveis, bastando para isto o ajuste de dois parâmetros.

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27

Vieira, Rodrigo. "Remoção de microalgas por pré-ozonização e flotação por ar dissolvido." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-28032017-104717/.

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Espécies de microalgas como Chlorella sorokiniana têm sido investigadas para as mais variadas aplicações como biocombustíveis, nutrição e a recuperação de nutrientes. Entretanto, a separação de microalgas do meio líquido permanece um desafio tanto técnico quanto econômico. O objetivo deste trabalho é propor e investigar a utilização de pré-ozonização e flotação por ar dissolvido para a separação sólido-líquido de Chlorella sorokiniana cultivada em meio padrão M8a em fotobiorreator flat panel, utilizando polímero catiônico à base de poliacrilamida como coagulante. Primeiramente, foi avaliado o sistema de tratamento com flotação por ar dissolvido, que foi otimizada em escala de laboratório visando eficiência de remoção de algas e flexibilização do sistema. Utilizando dosagens de polímero catiônico de 10 mg L-1 obteve-se remoções de cor aparente, turbidez e densidade óptica próximas de 95 % em pH 7. Posteriormente, a etapa de mistura lenta foi retirada do sistema, a razão de recirculação foi diminuída de 10 para 4 % e após essas alterações, obteve-se remoção de microalgas acima de 90 % para dosagem de polímero de 10 mg L-1. Para analisar o efeito da pré-ozonização a dosagem de polímero catiônico foi reduzida para 7 mg L-1, e observou-se que com FAD esta dosagem removeu 81,12 % de turbidez, e após pré-ozonização por 5 minutos seguida de FAD a eficiência de remoção de turbidez chegou a 91,78 % e remoção de cor aparente aumentou 6,25 %. A utilização da pré-ozonização permitiu utilização de velocidades de flotação da ordem de 24 cm min-1 sem prejuízo da eficiência de remoção de cor, turbidez e densidade óptica. Observou-se que a pré-ozonização demonstra efeitos positivos no sistema de tratamento, mas constatou-se uma dosagem ótima de ozônio, e que a partir desta dosagem a eficiência do tratamento pode ser prejudicada. Foi constatado que uma possível explicação para esse fato seja a liberação de matéria orgânica algal após pré-ozonização, em dosagens acima do valor ótimo de dosagem de ozônio.
Microalgal species as Chlorella sorokiniana have been investigated for a variety of applications such as biofuels, nutrition and nutrient recovery. However, the solid-liquid separation microalgae of the liquid medium remains a challenge both technical as economical. This work aims to propose and investigate the use of preozonation and dissolved air flotation for solid liquid separation of Chlorella sorokiniana cultivated in standard M8a medium in a flat panel photobioreator, using cationic polyacrylamide based polymer as coagulant. Initially, treatment system including dissolved air flotation was evaluated, which was optimezed at laboratory scale targeting removal efficiency of microalgae and system flexibility. Using cationic polymer dosage of 10 mg L-1, were obtained apparent color, turbidity and optical density removals nearly to 95% in pH 7. Further, the step of slow mixing was removed from the system, the recycle ratio was decreased from 10 to 4% and after these changes, was obtained microalgae removal over 90% at polymer dosage of 10 mg L-1. To analyse the effect of preozonation, cationic polymer dosage was decreased to 7 mg L-1, and was observed 81.12 % turbidity removal with this polymer dosage at FAD, and after 5 minutes preozonation followed by FAD, turbidity removal efficiency reached 91.8 % and apparent color removal increased 6.25 %. The utilization of preozonation allowed use of flotation velocities in the order of 24 cm min-1 without damaging variables removal efficiency. It was observed tha preozonation shows positive effects in treatment system, but was found an optimum ozone dosage from which the treatment efficiency is hampered. It was observed that a possible explanation to this fact is the release of algogenic organic matter after preozonation in dosages over the optimum value of ozone dosage.

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Henrard, Adriano Seizi Arruda. "Cultivo semicontínuo das microalgas Cyanobium sp. e Chlorella sp." reponame:Repositório Institucional da FURG, 2009. http://repositorio.furg.br/handle/1/2487.

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Dissertação(mestrado)- Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia e Ciência de Alimentos, Escola de Química e Alimentos, 2010.
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As microalgas se destacam por apresentarem diversas potencialidades, como fonte de alimento, obtenção de bioprodutos, produção de biocombustíveis e também podem contribuir na redução do efeito estufa, fixando CO2. As microalgas apresentam em sua composição alto teor de proteínas, ácidos graxos, minerais e pigmentos e, além disso, a microalga Chlorella possui certificado GRAS (Generally Recognized As Safe), podendo ser utilizada como alimento sem oferecer risco à saúde humana. Industrialmente, o cultivo semicontínuo de microalgas é muito empregado, pois com esse tipo de cultivo é possível a manutenção da cultura em crescimento por períodos mais prolongados, procedendo-se apenas a alimentação periódica do meio novo. O objetivo deste trabalho foi estudar o crescimento das microalgas Cyanobium sp. e Chlorella sp. cultivadas em modo semicontínuo e diferentes condições nutricionais e de processo. Assim, este trabalho foi dividido em 3 etapas: na primeira, objetivou-se estudar os cultivos das microalgas Cyanobium sp. e Chlorella sp. em diferentes condições nutricionais e de processo; na segunda etapa, avaliou-se o cultivo semicontínuo da microalga Cyanobium sp. em fotobiorreator tubular vertical de 2 L e na terceira, estudou-se o cultivo da microalga Chlorella sp. em modo semicontínuo em fotobiorreator aberto tipo raceway de 6 L. Para avaliar o melhor meio nutriente e agitação, os cultivos foram realizados em fotobiorreatores tipo erlenmeyer e raceway de 0,5 L e 6 L, respectivamente. Os cultivos foram realizados em condições controladas, estufa climatizada a 30ºC, 3200 Lux e fotoperíodo 12 h claro/escuro. O melhor meio de cultivo para as microalgas Cyanobium sp. e Chlorella sp. foi o meio BG11 com adição de bicarbonato de sódio, onde foram obtidas as maiores concentrações celulares (0,56 e 0,66 g.L-1), velocidades específicas de crescimento (0,303 e 0,166 d-1) e produtividades (0,120 e 0,089 g.L-1.d-1), respectivamente. Quando cultivadas sob diferentes agitações, as melhores respostas foram obtidas nos ensaios realizados com agitação por 2 bombas submersas, com concentrações máximas de biomassa 1,21 e 0,93 g.L-1 para Cyanobium sp. e Chlorella sp, respectivamente. Para o cultivo em modo semicontínuo da microalga Cyanobium sp., a máxima velocidade específica de crescimento foi 0,127 d-1 quando o cultivo foi realizado com concentração de corte 1,0 g.L-1, taxa de renovação 50% e concentração de bicarbonato de sódio 1,0 g L-1. Os máximos valores de produtividade (0,071 g.L-1.d-1) e número de ciclo (10) foram observados em concentração de corte 1,0 g.L-1, taxa de renovação 30% e concentração de bicarbonato 1,0 g.L-1. No cultivo semicontínuo com Chlorella sp., a maior velocidade específica de crescimento (0,149 d-1) foi obtida quando cultivada com 1,6 g.L-1 de bicarbonato de sódio e concentração de corte 0,6 g.L-1. A maior produtividade (0,091 g.L-1.d-1) foi obtida quando utilizado no cultivo concentração de corte 0,8 g.L-1, taxa de renovação de meio 40% e concentração de bicarbonato de sódio 1,6 g.L-1. Os resultados mostraram que o cultivo em modo semicontínuo é uma alternativa para maximizar a produção de microalgas, além disso, o sistema de cultivo deve ser escolhido não apenas pela maior produtividade, mas também de acordo com as características desejadas do produto.
Microalgae had gain attention for presenting diverse potentialities, as source of food, attainment of bioproducts, produce biofuels and also can contribute in the greenhouse effect reduction, fixing CO2. Microalgae presents in its composition high contents of protein, fatty acids, minerals and pigments, moreover, microalgae Chlorella possess the GRAS (Generally Recognized As Safe) certificate, being able to be used as food without offering any risk to the human health. The semicontinuous microalgae cultivation is very used, because of the long period cells maintenance, being necessary the periodic feeding of new cultivation medium. The objective of this work was to study the growth of the microalgae Cyanobium sp. and Chlorella sp. cultivated in semicontinuous mode and different nutritional and process conditions. This work was divided in three stages: in the first, the aim was to study the cultivation of the microalgae Cyanobium sp. and Chlorella sp. in different nutritional and process conditions; in the second stage, the semicontinuous cultivation of the microalgae Cyanobium sp. in vertical tubular photobioreactor of 2 L was evaluated; in the third, the culture of the microalgae Chlorella sp. was studied in semicontinuous mode in open photobioreactor type raceway of 6 L. To evaluate the best medium nutrient and agitation conditions, cultures were carried out under in photobioreactors type erlenmeyer and raceway of 0,5 L and 6 L, respectively. Cultures were carried out under controlled conditions, climatized greenhouse at 30ºC, 3200 Lux and 12 h photoperiod light/dark. The best culture medium for the microalgae Cyanobium sp. and Chlorella sp. was the BG11 medium with sodium bicarbonate addition, where were obtained the highest cell concentrations (0,56 and 0,66 g.L-1), specific growth rate (0,303 and 0,166 d-1) and productivity (0,120 and 0,089 g.L- 1.d-1), respectively. When cultivated under different agitation conditions, the best answers were obtained with agitation given by 2 submerged pumps, with maximum biomass concentrations 1,21 g.L-1 for Cyanobium sp. and 0,93 g.L-1 for Chlorella sp. For the culture in semicontinuous mode of the microalga Cyanobium sp., the maximum specific growth rate was 0,127 d-1 in the culture with cell concentration 1,0 g.L-1, renewal rate 50% and sodium bicarbonate concentration 1,0 g.L-1. The maximum productivity values (0.071 g.L-1.d-1) and cycle number (10) had been observed in cell concentration 1,0 g.L-1, renewal rate 30% and 1,0 g.L-1 bicarbonate concentration. In the semicontinuous culture with Chlorella sp., the highest specific growth rate (0,149 d-1) was gotten when cultivated with 1,6 g.L-1.d-1 of sodium bicarbonate and cell concentration 0,6 g.L-1). The highest productivity (0,091 g.L-1.d-1) was gotten when cell concentration 0,8 g.L-1, medium renewal rate 40% and sodium bicarbonate concentration 1,6 g.L-1 were used in the culture. Results had shown that semicontinuous mode culture is an alternative to maximize the microalgae production, moreover, the culture system must not only be chosen by the highest productivity, but also in accordance with the desired characteristics of the product.

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Tao, Ran. "Nutrient and organic matter removal from wastewaters with microalgae." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC2019/document.

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L'utilisation des microalgues dans le traitement des eaux usées est de plus en plus étudiée pour intégrer/remplacer les systèmes de traitement actuels permettant d'éliminer les nutriments et autres polluants. Cependant, l’utilisation des microalgues dans le traitement des eaux usées en est principalement au stade de la recherche, par exemple faible élimination des nutriments et croissance de la biomasse des microalgues. Le but de cette thèse était de permettre une élimination efficace des éléments nutritifs et de la matière organique des eaux usées par les microalgues tout en favorisant la production de biomasse de microalgues. C. vulgaris et S. acuminatus ont été cultivés dans des photobioréacteurs discontinus avec des digestats issus de la digestion anaérobie (AD) de boues biologiques de boue de vidange provenant d’une station d’épuration municipale (ADMW) et d’une usine de traitement des eaux usées d’une usine de pâtes et papiers (ADPP). Les rendements d’élimination de l’ammonium étaient supérieurs à 97% lorsque les deux microalgues étaient cultivées séparément dans de l’ADPP. Toutefois, 24 et 44% de l’ammonium ont été retirés de l’ADMW par C. vulgaris et S. acuminatus, respectivement. Les deux microalgues ont efficacement éliminé le phosphate (> 96%), tandis que la couleur (74–80%) et la DCO soluble (27–39%) ont été partiellement éliminées de ADMW et d'ADPP. La plus forte concentration de biomasse de S. acuminatus (7,8 à 10,8 g L-1 VSS) dans l'ADPP figure parmi les rendements les plus élevés signalés pour les microalgues dans les eaux usées réelles. Des rendements de biomasse supérieurs de S. acuminatus ont été obtenus dans de l'ADPP thermophile (10,2 ± 2,2 et 10,8 ± 1,2 g L-1) par rapport à de l'ADPP mésophile prétraité (7,8 ± 0,3 g L-1). En outre, les concentrations les plus élevées en biomasse et en méthane de microalgues ont été obtenues dans le même système intégré de culture de AD et de microalgues. Les concentrations de fer (0,1, 1,0 et 1,9 mg L-1) et de sulfure de soufre (3,7, 20 et 35,8 mg L-1) affectaient davantage l'efficacité de l'élimination de l'azote et la concentration de la biomasse de microalgues davantage dans les ammonium probablement dû à différents mécanismes d'assimilation de microalgues. Dans cette étude, le milieu contenant du nitrate comme source d'azote avec 1,0 mg de L-1 de fer et 35,8 mg de L-1 de sulfate et de soufre a permis d'obtenir la plus forte concentration de biomasse de microalgues. L'effet de la concentration en fer sur l'efficacité d'élimination des nitrates et la croissance des microalgues était plus significatif que la concentration en sulfate, alors que l'effet d'interaction entre le sulfate et le fer n'était pas observé. L'efficacité moyenne d'élimination de l'ammonium (14 à 30%) et la concentration en biomasse de microalgues (0,55 à 1,17 g de POC L-1) dans un photobioréacteur à membrane à flux continu ont été améliorées par addition de zéolite (0,5 g L-1). La zéolite fournissait probablement un habitat pour la croissance attachée de microalgues et une grande disponibilité d'ammonium pour la croissance à la surface de la zéolite en raison de l'adsorption d'ammonium par la zéolite. Une augmentation supplémentaire de la concentration en zéolite (de 0,5 à 1 et 5 g L-1) n’a pas amélioré l’efficacité de l’élimination de l’ammonium ni la concentration de la biomasse, probablement en raison de la turbidité accrue de la solution provoquée par la fragmentation de la zéolite ajoutée en particules plus fines, ce qui a réduit la disponibilité de lumière. Ces travaux ont montré la possibilité d'utiliser des microalgues dans le traitement des eaux usées pour éliminer efficacement les nutriments et les matières organiques, tout en favorisant la croissance des microalgues. La sélection d'espèces de microalgues adaptées aux eaux usées spécifiques pour éliminer les nutriments et les matières organiques est essentielle pour promouvoir les applications de traitement des eaux usées à base d'algues
Use of microalgae in wastewater treatment has been increasingly studied to integrate with or replace the present treatment systems for removal of nutrients and other pollu-tants. The potential advantages of this integration (wastewater treatment and microalgal cultivation) could be simultaneous recovery of nitrogen and phosphorus and the use of produced microalgal biomass as feedstock for e.g. biofuel, fertilizer and/or energy. However, the use of microalgae in wastewater treatment is mainly in research stage due to e.g. low nutrient removal and microalgal biomass growth. The aim of this thesis was to enable efficient nutrient and organic matter removal from wastewaters by mi-croalgae while promoting microalgal biomass production. Chlorella vulgaris and Scenedesmus acuminatus were successfully grown in batch photobioreactors with liquid digestates from anaerobic digestion (AD) of biosludge from a municipal wastewater treatment plant (ADMW) and a pulp and paper mill wastewater treatment plant (ADPP). The final ammonium removal efficiencies were above 97% when cultivating both microalgae separately in ADPP, however, only 24% and 44% of ammonium were removed from ADMW by C. vulgaris and S. acuminatus, respectively. Both microalgae efficiently removed phosphate (>96%), while color (74–80%) and sol-uble COD (27–39%) were partially removed from ADMW and ADPP. The obtained highest S. acuminatus biomass concentration (7.8–10.8 g L-1 VSS) in ADPP is among the highest yields reported for microalgae in real wastewaters. Higher S. acuminatus biomass yields were obtained in thermophilic ADPP (without and with pretreatment prior to AD: 10.2±2.2 and 10.8±1.2 g L-1, respectively) than in pretreated mesophilic ADPP (7.8±0.3 g L-1). In addition, the highest microalgal biomass concentration and methane yields were obtained in the same integrated AD and microalgal culti-vation system (thermophilic AD with pretreatment).The iron (0.1, 1.0, and 1.9 mg L-1) and sulfate-sulfur (3.7, 20, and 35.8 mg L-1) concen-trations were found to affect nitrogen removal efficiency and microalgal biomass con-centration more in the media with nitrate than with ammonium, probably due to different microalgal assimilation mechanisms for nitrate and ammonium. In this study, synthetic medium with nitrate as nitrogen source with 1.0 mg L-1 iron and 35.8 mg L-1 sulfate-sulfur enabled the highest microalgal biomass concentration. The effect of iron concentration on nitrate removal efficiency and microalgal growth was more significant than that of sulfate concentration, while the interaction effect between sulfate and iron was not observed. The average ammonium removal efficiency (14 to 30%) and microalgal biomass con-centration (0.55 to 1.17 g particulate organic carbon per L) in continuous-flow mem-brane photobioreactor were promoted by adding a low concentration of zeolite (0.5 g L-1). The zeolite likely provided a habitat for attached growth of microalgae and high availability of ammonium for growth on the surface of the zeolite due to ammonium adsorption to zeolite. Further increase in zeolite concentration (from 0.5 to 1 and 5 g L-1) did not improve ammonium removal efficiency or biomass concentration. This was likely due to the increased solution turbidity caused by breaking apart of added zeolite particles into finer particles, which reduced light availability.In summary, this work showed the possibility of utilizing microalgae in wastewater treatment to efficiently remove nutrients and organic matter, and simultaneously pro-mote microalgal growth. Selecting suitable microalgal species for the specific wastewater to remove nutrients and organic matter is essential to promote algae-based wastewater treatment applications

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Ríos, Pinto Luisa Fernanda 1981. "Estudo do crescimento da microalga Desmodesmus sp. visando a produção de biodiesel." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266120.

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Orientadores: Maria Regina Wolf Maciel, Luiz Fernando de Lima Luz Junior
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
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Resumo: Atualmente, a destruição ambiental devido à exploração inapropriada dos recursos naturais não renováveis, o aquecimento global, e a contaminação da biosfera causada, principalmente, pela globalização e um crescimento tecnológico acelerado, tem levado ao desenvolvimento de diversos combustíveis de fontes de energia renováveis, que sejam capazes de manter ou superar a eficiência dos hidrocarbonetos fósseis. Neste cenário, se deu o desenvolvimento do biodiesel, um combustível biodegradável derivado de fontes renováveis, o qual, na sua combustão, libera menos gases tóxicos, como são os óxidos de enxofre e nitrogênio. O biodiesel pode ser produzido a partir de gorduras animais, óleos vegetais ou biomassa. A fim de reduzir os custos da produção do biodiesel, matérias primas como os lipídios vêm sendo estudadas. Neste contexto, as microalgas oferecem uma série de vantagens como fonte de lipídios, como por exemplo, altas taxas fotossintetizantes, alta produção de biomassa e um rápido crescimento, se comparado, principalmente, com outras fontes de óleo vegetal. Neste trabalho, foi realizado o estudo do crescimento da microalga Desmodesmus sp. sob condição autotrófica, mixotrófica e heterotrófica com o objetivo de obter maior teor de lipídios na célula da microalga, visando a produção de biodiesel. Nas condições autotróficas, se obteve um crescimento de 53,1 Mcélulas mL-1. No cultivo mixotrófico, conseguiram-se 181 Mcélulas mL-1 e no heteretrófico atingiu-se 298 Mcélulas mL-1, todos no sexto dia de cultivo. As porcentagens de lipídios foram de 23%, 25% e 17% (m/m) da biomassa para o cultivo autotrófico, mixotrófico e heterotrófico, respectivamente. O óleo extraído do cultivo autotrófico, foi caracterizado via cromatografia gasosa e, a partir desta análise, produziu-se um óleo sintético (mistura de óleos vegetais e animais) com as características semelhantes da microalga para realizar a cinética da reação de transesterificação, num reator em batelada. A produção de biodiesel foi feita por transesterificação ácida, com excesso de etanol. O tempo de reação foi de 24 horas e obteve-se 90% de ésteres produzidos
Abstract: Currently, environmental destruction caused by inappropriate exploitation of non-renewable natural resources, global warming, and pollution of the biosphere caused mainly by globalization and accelerated technological growth has led to the development of various fuels from renewable source, which are able to maintain or exceed the effectiveness of fossil hydrocarbons. Biodiesel, a biodegradable fuel derived from renewable source, which releases less toxic gases such as sulfur and nitrogen oxides in its combustion. Biodiesel can be obtained from animal fats, vegetable oils or biomass. In order to reduce the cost of biodiesel production, raw materials such as lipids have been studied. In this context, microalgae offer a number of advantages as a source of fat, such as high photosynthetic rates, high biomass, and fast growth rate, compared to other sources of vegetable oil. The objective of this work was to study the autotrophic, mixotrophic and heterotrophic growths of microalgae Desmodesmus sp in order to optimize the levels of lipids in the microalgae cell to produce biodiesel. In autotrophic conditions, it was observed 5.31x107 cells ml-1; in mixotrophic were achieved 1.81x108 cells ml-1; and in heterotrophic reached 2.98x108 cells ml-1 were reached after sixth day of cultivation. The percentages of lipids of biomass for autotrophic, heterotrophic mixotrophic cultivation were 23%, 25% and 17% (m/m) respectively. Oil extracted from autotrophic cultivation was characterized via gas chromatography. A synthetic oil (mixture of vegetable and animal oils) with similar characteristics to the microalgae was used to perform the transesterification kinetics in a batch reactor. The production of such biodiesel was performed under acid conditions with excess of ethanol for 24 hours yielding 90% product
Doutorado
Desenvolvimento de Processos Químicos
Doutora em Engenharia Quimica

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Neto, JosÃ Fernandes da Silva. "Farinha de Spirulina como aditivo atrato-palatabilizante em dietas balanceadas para o camarÃo marinho Litopenaeus vannamei." Universidade Federal do CearÃ, 2010. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=6912.

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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
HÃ, presentemente, grande esforÃo de pesquisa no sentido de se substituir, parcial ou totalmente, a farinha de peixe das dietas artificiais por fontes protÃicas vegetais, de menor custo e maior previsibilidade de produÃÃo. Os resultados experimentais obtidos em alguns trabalhos evidenciam o bom potencial da farinha de Spirulina como aditivo impulsor do crescimento em dietas para camarÃes marinhos. Apesar de sua qualidade nutricional, nenhum trabalho foi conduzido atÃ agora sobre o uso da farinha de Spirulina como aditivo em dietas completas para L. vannamei. O presente trabalho objetivou o estudo do desempenho zootÃcnico e da preferÃncia alimentar de juvenis de Litopenaeus vannamei criados em laboratÃrio sob condiÃÃes controladas alimentados com diferentes dietas suplementadas ou nÃo com farinha de Spirulina. Juvenis de L. vannamei (3,89 Â 0,25 g) foram estocados intensivamente em 28 tanques circulares de polietileno de 500 L, na densidade de 44 camarÃes/tanque (64 juvenis/m2) por 71 dias. As dietas foram suplementadas com 0,5% de um atrativo comercial para raÃÃes de camarÃo (MAC e BAC) ou com 0,5% de farinha de Spirulina (MSP e BSP). Em MAC e MSP e em BAC e BSP houve reduÃÃes de 25% e 50% do nÃvel de inclusÃo de farinha de peixe, respectivamente. No segundo experimento, as dietas foram oferecidas aos animais em duas bandejas claramente identificadas, em quantidades iguais, colocadas no mesmo momento, em lados opostos dentro de cada tanque e foram recolhidas no mesmo instante. A raÃÃo remanescente em cada bandeja de alimentaÃÃo foi coletada e pesada para calcular o peso seco posteriormente. O ganho em peso semanal dos camarÃes alimentados com a raÃÃo MSP (0,89 Â 0,03 g) nÃo foi significativamente diferente daqueles que se alimentaram com a dieta MAC (0,89 Â 0,01 g) e P (0,95 Â 0,08 g). O fator de conversÃo alimentar e a taxa de eficiÃncia protÃica dos camarÃes alimentados com MSP nÃo foram estatisticamente diferentes daqueles observados em CN1 e P. O peso corporal final e a sobrevivÃncia dos camarÃes alimentados com MSP nÃo foram significativamente diferentes daqueles observados em CN1 e P. O estudo da atratividade mostrou que MSP teve preferÃncia significativamente maior pelos camarÃes do que a dieta MAC. Pode ser concluÃdo que a farinha de Spirulina adicionada a 0,5% em uma dieta completa para juvenis de L. vannamei atuou como um atrativo alimentar, e foi capaz de promover os mesmos efeitos de um aditivo comercial. Trabalhos futuros sÃo requeridos para avaliar outros nÃveis de inclusÃo, tÃcnicas de produÃÃo baratas, compostos responsÃveis pela atratividade da farinha de Spirulina etc
At present, there is a great effort to partially or completely replace fishmeal in artificial diets for less costly and more predictable vegetable protein ingredients. Experimental results of some studies indicate the potential of the Spirulina meal as a growth impeller in diets for marine shrimp. Despite its nutritional quality, no work has been conducted so far about the use of Spirulina meal as an additive in complete diets for Litopenaeus vannamei. The present work aimed at investigating the growth performance and feeding preference of L. vannamei raised under controlled laboratory conditions fed diets supplemented or deprived with Spirulina meal. Juveniles of L. vannamei (3.89  0.25 g) were stocked under intensive conditions at 44 shrimp/tank (64 juveniles/mÂ) in 28 polyethylene tanks of 500 L and raised for 71 days. Diets were supplemented with 0.5% of a commercial feed attractant for marine shrimp (MAC and BAC) or with 0.5% of Spirulina meal (MSP and BSP). In MAC and MSP and BAC and BSP, inclusion of fishmeal was reduced at 25% and 50%, respectively. In a second study, diets were offered to animals in a two feeding trays clearly identified, in equal amounts, delivered at the same time in the opposite sides of each tank and simultaneously recovered. Feed remaining in each feeding tray was collected and weighted to calculate the dry weight. Weekly shrimp weight gain fed diet MSP (0.89 Â 0.03 g) was not significantly different from those fed diet MAC (0.89 Â 0.01 g). Feed conversion rate and protein efficiency rate for shrimp fed diet MSP were not significantly different from those seen for CN1 and P. Final body weight and survival of shrimp fed diet MSP were not significantly different from those observed for CN1 and P. The attractability study demonstrated that MSP showed a significantly higher preference compared to MAC diet. It can be concluded that Spirulina meal added at 0.5% in a complete diet for juveniles of L. vannamei acted as a feeding attractant capable of promoting the same effects of a commercial additive. Further work is required to evaluate others inclusion levels, cheap production techniques, compounds responsible for attractabilityâs Spirulina meal etc

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Maciel, Rafael Lustosa. "Zootechnical performance and quality of filet tambaqui Colossoma macropomum fed with a diet supplemented cyanophyceae Spirulina platensis." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=12859.

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CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior
Tambaqui, Colossoma macropomum, is one of the most important fishery resources in the Amazon region and is the most cultivated native fish in Brazil due to omnivorous and its rusticity. Alternative ingredients for feed formulation are needed to maximize strength and weight gain of the animals when cultured at high stocking densities. The cyanophyceae Spirulina platensis is a microalgae with high nutritional, value rich in protein and vitamins, which has been used as an additive in diets for various species of fish. The aim of this study was to monitor the livestock development and the quality of the steak fry tambaqui fed diets with high inclusion levels of S. platensis. The study was divided into two phases. In the first phase, which lasted 60 days, we adopted a stocking density of 40 fish.m-2, while in the second phase, lasting 105 days, this value was halved. The feeding of animals was given four times a day with commercial diet with added 20% Spirulina (T1), with feed added Spirulina 40% (T2) and as a control (C) a commercial ration containing 50% was used crude protein (CP). At the end of the first phase, no statistically significant difference in survival or final biomass was observed, while the highest average final weight was observed in the control group (15.18 Â 0.57 g) was significantly higher than obtained in T1 (12 , 00 Â 1.40 g) and T2 (12.09 Â 1.22 g). In the second step also no statistically significant differences between treatments for the survival and final biomass was observed. As for the final average weight the highest value was again observed in the control, with 84.86 Â 8.44 g, significantly higher than those in T1 (75.87 Â 6.00) and T2 (70.68 Â 6.16). Quality analysis of fillet showed that fish which fed the diet containing 20% Spirulina (T2) presented protein level (17.78 Â 0.04%), lipid (1.23 Â 0.04) and energy (82.13 Â 0.18 Kcal/100g), significantly higher than the others treatments. We conclude that feeding tambaqui with Spirulina does not affect survival neither final biomass, in addition to increasing the nutritional value of fillet.
O tambaqui, Colossoma macropomum, Ã um dos mais importantes recursos pesqueiros da regiÃo amazÃnica alÃm de ser o peixe nativo mais cultivado no Brasil graÃas ao hÃbito alimentar onÃvoro e sua rusticidade. Ingredientes alternativos para a formulaÃÃo de raÃÃes sÃo necessÃrios para maximizar a resistÃncia e o ganho de peso dos animais quando cultivados em altas densidades de estocagem. A cianofÃcea Spirulina platensis Ã uma microalga com elevado valor nutritivo, rica em proteÃnas e vitaminas, que jÃ foi utilizada como aditivo em raÃÃes para vÃrias espÃcies de peixes. O objetivo deste trabalho foi acompanhar o desenvolvimento zootÃcnico e a qualidade do filÃ de alevinos de tambaqui alimentados com raÃÃes contendo elevados nÃveis de inclusÃo de S. platensis. A pesquisa foi dividida em duas fases. Na primeira fase, que teve duraÃÃo de 60 dias, adotou-se uma densidade de estocagem de 40 peixes.m-2, enquanto na segunda fase, com duraÃÃo de 105 dias, esse valor foi reduzido pela metade. A alimentaÃÃo dos animais foi feita quatro vezes ao dia com raÃÃo comercial adicionada de 20% de Spirulina (T1), com raÃÃo adicionada de 40% de Spirulina (T2) e, como controle (C) foi utilizada uma raÃÃo comercial contendo 50% de proteÃna bruta (PB). Ao termino da primeira fase, nÃo foi observada diferenÃa estatÃstica significativa na sobrevivÃncia nem na biomassa final, enquanto o maior peso mÃdio final foi observado no grupo controle (15,18Â0,57 g), sendo significativamente superior aos obtidos em T1 (12,00Â1,40g) e T2 (12,09Â1,22g). Na segunda etapa tambÃm nÃo se observou diferenÃas estatÃsticas significativas entre os tratamentos quanto Ã sobrevivÃncia e a biomassa final. Quanto ao peso mÃdio final o maior valor foi, mais uma vez, observado no controle, com 84,86 Â 8,44 g, significativamente superior aos encontrados em T1(75,87Â6,00) e T2(70,68Â6,16). A anÃlise da qualidade do filÃ revelou que os obtidos dos peixes alimentados com a raÃÃo contendo 20% de Spirulina (T2) apresentaram nÃvel proteico (17,78Â 0,04%), lipÃdico (1,23Â 0,04) e energÃtico (82,13Â 0,18 Kcal/100g), significativamente superior aos demais. Conclui-se que a suplementaÃÃo de Spirulina na raÃÃo do tambaqui nÃo afetou a sobrevivÃncia nem a biomassa final e ainda aumentou o valor nutricional do filÃ.

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POUSA, KURPAN NOGUEIRA DANIEL. "Diversity of sulfur metabolism in microalgae." Doctoral thesis, Università Politecnica delle Marche, 2021. http://hdl.handle.net/11566/289649.

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Lo zolfo è un macronutriente fondamentale, ma spesso sottovalutato sostanzialmente meno informazioni su di esso in letteratura rispetto ad altri macronutrienti. Tra gli organismi fotosintetici, il metabolismo dello zolfo è generalmente si presume di essere conservato e la maggior parte delle informazioni disponibili è limitata alle pianti vascolari. L'indagine sulle alghe è limitata a pochissimi cladi, nonostante il importanza del solfato - la forma più disponibile di zolfo in natura - nell'acqua di mare. Infatti, ci sono prove che suggeriscono che la concentrazione di solfato nell'acqua di mare sia una delle maggiori importanti fattori determinanti della composizione del fitoplancton e potrebbero essere i responsabili di oggi predominanza delle microalghe clorofilla a + c nel fitoplancton - la facilitazione del solfato Ipotesi (SFH). Di fronte a questo scenario, questa tesi intende aumentare la comprensione di il ruolo dello zolfo nel fitoplancton implementando un approccio multidisciplinare coinvolgendo vari gruppi di microalghe. In primo luogo, un'ampia analisi in silico del cellulare localizzazione e relazioni filogenetiche dei sei enzimi fondamentali dell'assimilazione dei solfati mostra un'origine piuttosto complessa del percorso. I dati suggeriscono anche un ruolo rilevante di redox regolazione, che sembra funzionare in modo diverso tra i diversi gruppi di fototrofi. Quindi, la funzione, la localizzazione e la regolazione redox in vivo di uno di questi enzimi - con una filogenesi particolarmente complessa, denominata ATPS - è stata ulteriormente indagata nel modello di diatomee Phaeodactylum tricornutum utilizzando nuove tecniche di biologia molecolare. L'ATPS sembra essere cruciale per la vita ed è presente in P. tricornutum come due non ridondanti isoforme che si trovano in diversi compartimenti e possono funzionare nel partizionamento dello zolfo. Il recupero di mutanti knockout ATPS mediante complementazione con mezzo di crescita Vengono inizialmente studiate fonti alternative di zolfo. Infine, utilizzando un fisiologico e approccio biochimico, la crescita di microalghe marine appartenenti a vari gruppi è stata valutato in funzione della concentrazione di solfato nel mezzo di crescita. La concentrazione di il solfato che si traduce in limitazione della crescita è sorprendentemente diverso tra le microalghe. Infatti, le microalghe clorofilla a + c possono essere limitate in concentrazioni di solfato fino a 10000 volte superiore alle altre microalghe, che è altamente congruente con l'SFH. È interessante notare che le loro risposte alla limitazione dei solfati erano anche diverse all'interno delle alghe con plastide rosse, soprattutto nella quota di ferro nelle cellule.
Sulfur is a fundamental, yet frequently underestimated, macronutrient resulting on substantially less information about it in literature when compared to other macronutrients. Among photosynthetic organisms, sulfur metabolism is generally assumed to be conserved and most of the available information is limited to vascular plants. The investigation among algae is constrained to very few clades, despite the importance of sulfate – the most available form of sulfur in nature – in seawater. In fact, there is evidence to suggest that sulfate concentration in seawater is one of the most important drivers of phytoplankton composition and may be the responsible for today’s dominance of chlorophyll a + c microalgae in the phytoplankton – the Sulfate Facilitation Hypothesis (SFH). Facing this scenario, this thesis intends to raise the understanding of the role of sulfur in phytoplankton by implementing a multidisciplinary approach involving various groups of microalgae. First, a broad in silico analysis of the cellular localization and phylogenetic relationships of the six core enzymes of sulfate assimilation shows a rather complex origin of the pathway. Data also suggests a relevant role of redox regulation, that appears to function differently among different groups of phototrophs. Then, the function, localization and the in vivo redox regulation of one of these enzymes – with a particularly complex phylogeny, named ATPS – was further investigated in the model diatom Phaeodactylum tricornutum using novel molecular biology techniques. ATPS seems to be crucial for life and is present in P. tricornutum as two non-redundant isoforms that are in different compartments and may function in sulfur partitioning. The recovery of ATPS-knockout mutants by growth medium complementation with alternative sources of sulfur is initially investigated. Finally, using a physiological and biochemical approach, the growth of marine microalgae belonging to various groups was assessed as a function of sulfate concentration in growth medium. The concentration of sulfate that results in growth limitation is strikingly different among microalgae. In fact, chlorophyll a + c microalgae can be limited in sulfate concentrations up to 10000-fold higher than the other microalgae, which is highly congruent with the SFH. Interestingly, their responses to sulfate limitation were also different within the red-plastid algae, especially in the iron quota in cells.

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Moulin, Solène. "Synthesis of hydrocarbons in algae : from biodiversity to biotechnology." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0429.

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Les hydrocarbures (HCs) sont prédominants dans notre économie actuelle (carburants, cosmétiques, chimie, etc.) mais sont quasi-exclusivement issus des ressources fossiles. Les problématiques de changement climatique et d’épuisement des ressources poussent les recherches vers l’étude et la domestication des voies de synthèse naturelles d’HCs. Lorsque j’ai commencé ma thèse, une enzyme de biosynthèse d’HC, l’acide gras photodécarboxylase (FAP) venait d’être découverte chez la microalgue Chlorella. J’ai d’abord caractérisé son homologue chez la microalgue modèle Chlamydomonas. Une étude phylogénétique de la famille des GMC oxidoréductases à laquelle appartient la FAP a permis d’identifier un large réservoir de de 200 FAPs putatives. La caractérisation biochimique de plusieurs d’entre elles a permis de montrer qu’une FAP fonctionnelle a été conservée lors des endosymbioses secondaires. Cela suggère que la FAP joue un rôle important chez les algues. Ce rôle a été étudié par une approche de génétique inverse chez Chlamydomonas. La caractérisation physiologique de mutants knockout a permis de démontrer le rôle de la FAP dans la synthèse d’HCs dans le chloroplaste et de mettre en évidence des modifications physiologiques transitoires. Des mécanismes de compensation à l’absence d’HCs restent donc à découvrir. Dans une dernière partie, j’ai développé une souche d’E. coli exprimant la FAP et une thioestérase. Cette souche produit en continu des HCs dans la phase gaz des cultures, ce qui permet une récolte facilitée du produit d’intérêt sous forme pure. Cette étude constitue une preuve de concept que la FAP pourrait être utilisée pour la production biosourcée d’HCs
Hydrocarbons (HCs) are predominant in our current economy (fuels, cosmetics, chemicals, etc.) but are almost exclusively derived from fossil resources. Climate change and resource depletion concerns are pushing research towards the study and domestication of natural HC synthesis pathways. When I started my thesis, a HC forming enzyme, the fatty acid photodecarboxylase (FAP) had just been discovered in the microalgae Chlorella. I first characterised its homolog in the model microalgae Chlamydomonas. A phylogenetic study of the GMC oxidoreductase family to which the FAP belongs has allowed identification of a large reservoir of 200 putative FAPs. Biochemical characterisation of several of them showed that a functional FAP was maintained during secondary endosymbiosis. This suggests that FAP plays an important role in algae. This role has been studied by a reverse genetic approach in Chlamydomonas. The physiological characterisation of knockout mutants demonstrated the role of FAP in the synthesis of HCs in chloroplasts as well as transient physiological changes. Mechanisms to compensate for the absence of HCs therefore remain to be discovered. In a last part, I developed a strain of E. coli expressing the FAP and a thioesterase. This strain continuously produces HCs in the gas phase of the cultures, which allows an easier harvesting of the product of interest in a pure form. This study is a proof of concept that FAP could be used for the biobased production of HCs

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Johnsson, Nathalie, and Fredrik Steuer. "Bioplastic material from microalgae : Extraction of starch and PHA from microalgae to create a bioplastic material." Thesis, KTH, Materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231508.

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Microalgae used in sewers to capture CO2 eventually turns into waste material. Through the use oftheir biomass, the waste algae can be given a new purpose. In this study attempts to extract starch or PHA from three different algae; Calothrix Scytonemicola, Scenedesmus Almeriensis and Neochloris Oleoabundans, were made. We also attempted to create a bio-based plastic material. Both Scenedesmus Almeriensis and Neochloris Oleoabundans are starch rich microalga. By washing with acetone, cryo grinding, use of ultrasonic homogenizer and dialysis, starch was likely extracted successfully. The extracted material and the plasticiser Carboxymethyl Cellulose (CMC) was used to cast plastic film. The cast film was very thin and brittle; perhaps by using different plasticisers or additives a more usable bio-based plastic material can be created. The PHA rich algae Calothrix Scytonemicola was used to extract PHA. The algae was washed with acetone, cryo grinded and then mixed with Sodium Hypochlorite(aq) and deionised water to extract the desired PHA. Due to a shortage of algae very small amounts of material could be extracted. Therefore, the casting of a plastic film was performed with commercial PH3B, which is a type of PHA. Three attempts were conducted. The first one with only chloroform, the second one with CMC and chloroform and the last one with Sucrose Octaacetate and chloroform. The film with Sucrose Octaacetate gave the best plastic material in regards to mechanical properties.
Mikroalger som används i kloaker för att binda CO2 blir till slut restavfall. Genom att använda dess biomassa kan restalgerna få ett nytt syfte. I denna studie utfördes extraktionsförsök av stärkelse samt PHA från tre olika alger, Calothrix Scytonemicola, Scenedesmus Almeriensis och Neochloris Oleoabundans. Ytterligare försök genomfördes för att försöka framställa ett biobaserat plastmaterial. Både Scenedesmus Almeriensis och Neochloris Oleoabundans är stärkelserika mikroalger. Genom att tvätta dem med aceton, kryomalning, användning av en ultrasonic homogenizer och dialys kunde stärkelse troligtvis extraheras. Det extraherade materialet blandades med karboxymetylcellulosa (CMC) för att skapa en plastfilm. Filmen blev väldigt tunn och spröd, således behövs antingen en annat mjukningsmedel eller tillägg av additiv för att skapa ett mer användningsbart biobaserat plastmaterial. Den PHA-rika algen Calothrix Scytonemicola användes vid extraktionen av PHA. Algerna tvättades med aceton och kryomaldes innan PHA förhoppningsvis extraheras med hjälp av natriumhypoklorit(aq) och avjonat vatten. På grund av en för liten mängd tillgänglig alg extraherades endast en liten mängd material. Det var därför inte möjligt att skapa en plastfilm av vårt extrakt utan istället användes kommersiell PH3B, som är en typ av PHA. Tre försök genomfördes, en med endast kloroform, en med CMC och kloroform och den sista med sucrose octaacetate och kloroform. Den sistnämnda filmen gav det bästa plastmaterialet med avseende på de mekaniska egenskaperna.

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Audoin, Coralie. "Valorisation de métabolites secondaires issus de micro-algues : approches métabolomiques, isolement et caractérisation structurale." Thesis, Nice, 2013. http://www.theses.fr/2013NICE4068.

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Les microalgues présentes à la fois dans les eaux douces et salées compteraient plus de 200 000 espèces. Cette diversité en fait une source potentielle de métabolites spécialisés originaux. Parmi les principales familles de substances naturelles valorisées actuellement, on peut citer les pigments, lipides, protéines, polysaccharides, caroténoïdes. Une vision plus globale du métabolome de chacune des espèces apparaît aujourd’hui nécessaire pour mieux mettre en valeur le potentiel commercial que représente cette « microbiodiversité ». Pour cela, nous avons tout d’abord choisi d’approcher le métabolome de différentes souches de microalgues cultivées au sein de la Société Greensea en s’appuyant sur les techniques d’HPTLC, de RMN et d’UHPLC-QTOF pour une visualisation large. Cette étude nous a permis de regrouper les espèces par analogie métabolique après traitement statistique des données. Une seconde partie a consisté en une étude phytochimique approfondie de certaines souches et a conduit à l’isolement et la caractérisation de plusieurs molécules. Ainsi, en plus de métabolites connus, un peptide original portant un motif isoprényl, le cumbriamide a été caractérisé au sein de Lyngbya sp. et une première évaluation de son potentiel thérapeutique a été entreprise. Une large diversité en glycolipides s’est montrée prépondérante dans de nombreuses souches et une méthode de caractérisation a pu être mise au point pour leur identification par UHPLC-QTOF. Enfin, différentes applications des approches métabolomiques ont été envisagées. Ainsi, des études chimiotaxonomiques ont été menées sur les différentes souches de microalgues et l’influence de changements de conditions de culture sur la production de métabolites chez Nannochloropsis oculata a été observée
Microalgae are present both in Oceans and freshwaters and could include more than 200 000 species. This diversity is a source of original specialized metabolites that can find a large array of applications. Pigments, lipids, proteins, polysaccharides and carotenoids are usual compounds produced by microalgae that have found commercial applications. A global vision of the metabolome of each species has showed promises to highlight the commercial value of this “microdiversity”. We then decided to assess the metabolome of several microalgae species grown at the Greensea company by using HPTLC, NMR and UHPLC-QTOF techniques for a rapid and global overview. A classification of the species according to their metabolomics similarities was obtained after statistics treatment of the data. A second part was dedicated to a phytochemical study of the extracts of selected strains and led to the isolation and characterization of several metabolites. Thus, in addition to known molecules, an original peptide substituted by an isoprenyl moiety and named cumbriamide has been characterized in Lyngbya sp and a first assessment of its therapeutical potential has been undertaken. Glycolipids have been identified as the major metabolites in the extracts of numerous strains and a UHPLC-QTOF method was developed for their identification. Finally, several applications of the metabolomics approaches were considered. Chemotaxonomic studies were first carried out and the influence of growth conditions on the metabolome of Nannochloropsis oculata was observed

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Rodrigues, Simone Cristina. "Produção de éster etílico via reação in situ a partir da biomassa da Chlamydomonas reinardtii." Universidade Estadual do Oeste do Paraná, 2016. http://tede.unioeste.br:8080/tede/handle/tede/2909.

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For some years, the environment has been one of the main concerns of the global population. The need for alternative sources and ecologically friendly practices, as well as biofuels, is an option that fits sustainable development. In search for high oil content raw materials, microalgae have been considered as a useful and promising source of biodiesel. Thus, the paper aimed to evaluate the production of ethyl esters via in situ reaction of the biomass obtained in the cultivation Chlamydomonas reinhardtii microalgae, to determine the best cultivation medium based on productivity, to develop microalgae cultivation for biomass production, to determine lipid content, the in situ reaction for ethyl esters production characterize and quantify the obtained esters. From the results obtained with the extraction, it was observed that the characteristics of the solvents can promote the lipid extraction of the biomass. Chlamydomonas reinhardtii microalgae was cultivated in TAP medium, with controlled artificial light and temperature. Then, there was the recovery of the biomass, which analyzed for chlorophyll a and b proteins and total carbohydrates and finally, the lipid content in the biomass was obtained and quantified by analyzing the ethyl esters present by gas chromatography. The chlorophyll, protein and carbohydrate contents were: 54.136 mg / L -1, 29.39% and 14.92%, respectively, and the highest lipid content was 4.03%. The yield of the biomass culture was of 0.646 gL-1. From the results obtained with the extraction, it was observed that, the polarity of the solvent influences the productivity of lipids. In the production of esters the predominant in situ reaction is the temperature and reaction time, with the highest yields at 60ºC (1.504 mg of ester/g of biomass in 30, 1.518 mg of ester/g of biomass in 45 and 1.509 mg of ester/g of biomass in 60 minutes). In the production of esters, the factor analysis showed that there was interaction between temperature and time, on average, the best yields in number of C15 and C16 cetanes being C16 (76.97% at 30°C, 58.21% at 45°C, 64.05 % In 60°C and 56.79% in 75°C) profile of esters obtained, suitable for the production of biodiesel. The obtained results showed that the Chlamydomonas reinhardtii microalgae biomass presents potential for biodiesel production, when cultivated under the conditions tested in this study.
O meio ambiente há alguns anos vem sendo uma das principais preocupações da população mundial. A necessidade de fontes alternativas de energia e de práticas ecologicamente corretas, assim como os biocombustíveis, surgem como uma opção que se ajusta ao desenvolvimento sustentável. Na busca por matérias primas com alto teor de óleo, as microalgas têm sido consideradas como uma fonte útil e promissora de biodiesel. Desta forma, o trabalho teve como objetivo a avaliação da produção de ésteres etílicos via reação in situ da biomassa obtida no cultivo da microalga Chlamydomonas reinhardtii, determinar o melhor meio de cultivo baseado na produtividade, desenvolver o cultivo de microalga para a produção de biomassa, determinar o teor de lipídios, a reação in situ para a produção de ésteres etílicos caracterizar e quantificar os ésteres obtidos. A partir dos resultados obtidos com a extração, observou-se que as características dos solventes podem favorecer a extração lipídica da biomassa. A microalga Chlamydomonas reinhardtii foi cultivada em meio TAP, com luz artificial e temperatura contraladas. Após houve a recuperação da biomassa, esta foi analisada quanto ao teor de clorofila a e b proteínas e carboidratos totais e por fim, foi obtido e quantificado o teor lipídico presente na biomassa, analisando-se o perfil de ésteres etílicos presentes por cromatografia gasosa. O teor de clorofila, proteína e carboidratos encontrados foram: 54,136 mg./L-1, 29,39% e 14,92%, respectivamente, e o maior teor de lipídeo foi de 4,03% o rendimento do cultivo de biomassa foi de 0,646 g.L-1. A partir dos resultados obtidos com a extração, observou-se que, a polaridade do solvente influencia na produtividade de lipídios. Na produção de ésteres o que predomina na reação in situ é a temperatura e o tempo de reação, apresentando maiores rendimentos a temperatura de 60ºC (1,504 mg de éster/g de biomassa em 30, 1,518 mg de éster/g de biomassa em 45 minutos e 1,509 mg de éster/g de biomassa em 60 minutos). Na produção de ésteres, a análise fatorial revelou que houve interação entre temperatura e tempo, em média, os melhores rendimentos em número de cetanos C15 e C16 sendo C16 (76,97% em 30ºC, 58,21% em 45Cº, 64,05% em 60Cº e 56,79% em 75CºC) perfil de ésteres obtidos, propícios para a produção de biodiesel. Os resultados obtidos demonstram que a biomassa microalga Chlamydomonas reinhardtii apresenta potencial para produção de biodiesel, quando cultivada nas condições testadas neste estudo.

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Fernandes, Maiara Sousa. "Desenvolvimento de métodos otimizados para criopreservação de microalgas verdes (Chlorophyta)." Universidade Federal do Tocantins, 2017. http://hdl.handle.net/11612/434.

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Frente à importância da preservação dos recursos genéticos algais depositados em coleções de referência para o apoio de programas de melhoramento, faz-se necessário o desenvolvimento de metodologias para a conservação de microalgas em estado metabolicamente inativo por longos períodos. Neste contexto, objetivou-se com o presente trabalho estabelecer protocolos otimizados de criopreservação para espécies de microalgas com arquiteturas celulares distintas (colonial cenobial, cocóide unicelular e colonial palmeloide), determinando-se os parâmetros ótimos para o congelamento, incluindo a fase de crescimento algal, além do tipo e da concentração de agentes crioprotetores. Foram testados três agentes químicos crioprotetores: dois agentes com alta permeabilidade celular, Glicerol e Dimetilsulfóxido (DMSO), e um agente não-permeável, Polietilenoglicol 400 (PEG 400). A otimização das variáveis foi realizada empregando-se delineamento composto central rotacional (DCCR) 22. Para a maioria das cepas unicelulares cocóides analisadas o congelamento durante a fase de desaceleração do crescimento algal (6º dia de cultivo) na presença do crioprotetor DMSO 7% (v/v) resultou nas taxas mais elevadas de viabilidade celular após a criopreservação (até 94%). Por outro lado, as taxas mais altas de recuperação da viabilidade celular de algas cenobiais (62,6%) foram obtidas mediante congelamento durante a fase de crescimento algal exponencial (3º dia de cultivo) na presença dos agentes glicerol e PEG 400 combinados na concentração de 5% (v/v) cada. Comportamento distinto também foi observado para as cepas palmelóides analisadas, com as taxas de recuperação mais elevadas (78,8%) tendo sido obtidas mediante congelamento durante a fase de desaceleração do crescimento algal (6º dia de cultivo) na presença da combinação de agentes crioprotetores, glicerol (5% v/v) + PEG 400 (5% v/v). Os resultados obtidos sugerem que a morfologia apresentada pelo talo algal pode ser um bom indicador para a escolha do agente crioprotetor a ser utilizado para a criopreservação.
In view of the importance of preserving algal genetic resources deposited in reference collections for the support of enhancement programs, it is necessary to develop methodologies for the conservation of microalgae in a metabolically inactive state for long periods. In this context, the objective of this work was to establish optimized cryopreservation protocols for microalgae species with distinct cellular architectures (cenobial colonial, unicellular coccoid and palmeloid colonial), determining the optimal parameters for freezing, including the algal growth phase, and also the type and concentration of cryoprotective agents. Three cryoprotectants were tested: two agents with high cell permeability, Glycerol and Dimethylsulfoxide (DMSO), and a non-permeable agent, Polyethylene Glycol 400 (PEG 400). The optimization of the variables was carried out using a central composite rotational design (CCRD) 22. For most of the single-celled coccoid strains analyzed, the freezing during the deceleration phase of algal growth (6th day of culture) in the presence of 7% DMSO cryoprotectant v/v) resulted in the highest rates of cell viability after cryopreservation (up to 94%). On the other hand, the highest rates of cellular viability of the cenobial algae (62.6%) were obtained by freezing during the exponential algal growth phase (3rd day of cultivation) in the presence of combined glycerol and PEG 400 agents in the concentration of 5% (v / v) for each one. Different behavior was also observed for the analyzed palmeloid strains, with the highest recovery rates (78.8%) being obtained by freezing during the deceleration phase of algal growth (6th day of culture) in the presence of the combination of cryoprotectants, glycerol (5% v/v) + PEG 400 (5% v/v). The results obtained suggest that the morphology presented by the algal stem can be a good indicator for the choice of cryoprotectant to be used for cryopreservation.

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Dias, Felipe Augusto Pereira. "Avaliação técnico-econômica da implementação de um sistema de cultivo de microalgas na usina termelétrica Barbosa Lima Sobrinho com vista à biofixação de CO2." Universidade do Estado do Rio de Janeiro, 2011. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=2734.

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Este estudo teve como finalidade levantar dados para uma avaliação das alternativas tecnológicas (cultivos de microalgas e reflorestamento) para a biofixação de CO2 da atmosfera próxima à usina termelétrica; tendo sido utilizada como referência a Usina Barbosa Lima Sobrinho. Já existe um projeto de avaliação do efeito do reflorestamento na fixação do CO2 nesta usina e, neste trabalho, foi avaliada a alternativa do cultivo de microalgas. Uma pesquisa inicial foi feita na literatura para verificar qual a espécie de microalga seria a mais adequada para ser utilizada no estudo, tendo sido a espécie Chlorella sp. a selecionada. Posteriormente os sistemas de cultivo de microalgas mais comumente empregados no mercado foram levantados e foi selecionado o cultivo em tanques abertos como referência para a modelagem do processo. Utilizando os dados da termelétrica e da literatura foi possível estimar a quantidade de CO2 que será retirada da atmosfera caso um sistema de cultivo seja efetivamente instalado na usina termelétrica. Uma análise econômica foi realizada para determinar a viabilidade do projeto. Os resultados indicam que a utilização deste tipo de tecnologia é promissora
This study aimed to collect data for an evaluation of alternative technologies (microalgae cultivations and reforestation) for biofixation of CO2 from the atmosphere near a power plant, named Barbosa Lima Sobrinho, which uses natural gas and diesel as fuels. There is a project to assess the effect of reforestation for CO2 fixation in this facility and, in this study, we evaluated the alternative of cultivating microalgae. An initial review was done in the literature to determine what species of microalgae would be most suitable to use and Chlorella sp was selected. Thereafter cultivation of microalgae media, commonly employed in the market, were evaluated and the culture selected was in open tanks as a reference for the modeling process. Using data from the thermoelectric and the literature it was possible to estimate the amount of CO2 that will be capture from the atmosphere if a microalgae farming will be installed in thermal power plant area. An economic analysis was performed to determine the feasibility of the project. The results indicate that the use of this technology is promising

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Ramirez, Nelzy Neyza Vargas. "Estudo do crescimento da microalga Scenedesmus Sp. em vinhaça." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/105064.

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A vinhaça é o resíduo mais abundante gerado no processo de produção de etanol, sendo que a cada litro de etanol são gerados de 10 a 18 litros de vinhaça. Sua disposição é tema de grande preocupação, por sua elevada carga de matéria orgânica e o pH ácido. Embora seja um resíduo poluente, contém macronutrientes que podem ser usados para o cultivo de micro-organismos úteis aos seres humanos como é o caso apresentado neste trabalho, onde a vinhaça foi utilizada para cultivo da microalga Scenedesmus sp. As microalgas são apontadas como uma alternativa promissora para substituição dos combustíveis fósseis. Entretanto, seu custo ainda é elevado devido a vários fatores, dentre os quais os nutrientes que devem ser fornecidos para crescimento. Assim, o uso de rejeitos como fonte de nutrientes pode auxiliar a reduzir este balanço desfavorável. Este trabalho teve como objetivo avaliar a viabilidade técnica de produção da Scenedesmus sp. para tratar vinhaça de etanol de cana de açúcar. Inicialmente, testou-se a viabilidade de crescimento da microalga nesses meios. Uma vez corroborado que é possível seu crescimento, foram realizados planejamentos experimentais que avaliaram os fatores que influenciam no crescimento. O planejamento fatorial demonstrou que é possível cultivar microalgas em concentrações de até 40% de vinhaça. O planejamento composto central rotacional demonstrou o seguinte: a intensidade luminosa e a porcentagem de vinhaça influenciam na quantidade de biomassa a ser produzida, e a temperatura, entre 20 e 35°C, não tem um efeito significativo quando se trabalha com porcentagens menores que 40% de vinhaça. Foram analisados parâmetros como o DBO, conteúdo de nitrogênio e fósforo, que demonstraram que fotobiorreatores com até 32% geram vinhaça tratada com valores de DBO menores que 106 mg/L, conseguindo remover até 96% de nitrogênio e 99,9% de fósforo. Como dado adicional se avaliou os métodos de espectrofotometria e espectroscopia de fluorescência, que se mostraram métodos adequados para acompanhar o crescimento microalgal em fotobiorreatores.
Vinasse is one of the most polluting wastes generated in the process of ethanol production,with each liter of ethanol are generated between 10 to 18 liters os vinasse. Its suitable disposal is an issue of great concern due to its high load of organic matter and acidity. Although this is a polluting waste, contains nutrients which can be used for cultivation of micro-organisms that may be useful to humans as is the case presented in this work, where vinasse was used for cultivation of the microalgae Scenedesmus sp. Microalgae are currently reported in the literature as a promising alternative to replace fossil fuels. However, its cost is still high due to several factors, such as the nutrients that must be supplied for growth. Thus, the use of waste as a source of nutrients may assist in reducing this unfavorable balance. This study aimed to evaluate the technical feasibility of production of microalgae Scenedesmus sp. to treat ethanol stillage. First, cultivations with different percentages of vinasse were done aiming to verify wether they are able to grow in medium supplemented with vinasse. The factorial design has shown that it is possible to cultivate microalgae at concentrations up to 40% of vinasse in the culture medium. The central composite design showed that light intensity and percentage of vinasse influence the amount of biomass to be produced. Additionally, the temperature between 20 and 35°C has not a significant effect when working with percentages smaller than 40% of vinasse. The analyzed parameters were BOD, nitrogen and phosphorus content demonstrated that photobioreactors with up to 32% vinasse generate vinasse treated with BOD values lower than 106 mg/L achieving a remotion of 96% nitrogen and 99.9% phosphorus. Finally, it was also shown that spectrophotometry and 2D fluorescence spectroscopy are suitable methods for monitoring the microalgae growth.

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Ávila, Peltroche José Giovanni Jesús. "Evaluación de la remoción de nitratos y fosfatos a nivel laboratorio por microalgas libres e inmovilizadas para el Tratamiento Terciario de Aguas Residuales Municipales." Bachelor's thesis, Universidad Ricardo Palma, 2015. http://cybertesis.urp.edu.pe/handle/urp/840.

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El presente estudio tuvo como objetivo determinar la capacidad de remoción de nitratos (N-NO3⁻) y fosfatos (PO₄³¯) en Aguas Residuales Municipales (ARM) por microalgas libres e inmovilizadas. Se utilizaron cepas provenientes de los afluentes de la Planta de Recuperación de las Aguas del Río Surco (Lima, Perú) y se evaluó su capacidad de remoción de N-NO3⁻ y PO₄³¯ durante 10 días, a nivel laboratorio, en ARM con tratamiento primario, tanto de forma libre como inmovilizadas en discos de alginato de sodio al 4%. Los cepas obtenidas se identificaron como Chlorella sp y Chlamydomonas sp. Ambas tuvieron un buen crecimiento en ARM, especialmente Chlamydomonas sp, la cual reportó los mayores valores en los parámetros cinéticos de crecimiento. El cultivo de Chlorella sp. libre fue el que registró uno de los valores más altos de porcentaje (71.25%) y tasa de remoción (0.43 mg/l/día) de N-NO3⁻, y los máximos valores de dichos parámetros para PO43- (83.69%; 0.09 mg/l/día), así como para el índice de eficacia (EI) de ambos nutrientes, comparado con los de Chlamydomonas sp. Los cultivos inmovilizados de ambas especies reportaron valores altos de remoción, entre 56% a 67% para N-NO3⁻ y 78% a 81% para PO43-, este último fue removido en 24 horas en la mayoría de los cultivos. La inmovilización fue el principal factor que afectó la capacidad de remoción de nutrientes. Ambas cepas mostraron ser eficientes en la remoción de nutrientes en ARM, especialmente de PO43-, con valores cercanos a los máximos reportados para ambas especies en estudios previos.The aim of this investigation was to determinate the nitrate (N-NO3⁻) and phosphate (PO43-) removal capacity of free and immobilized microalgae in Municipal Wastewater (MW). Strains were isolated from Planta de Recuperación de las Aguas del Río Surco (Lima, Perú) influent. Their N-NO3⁻ and PO43- removal capacity were evaluated during 10 days in MW with primary treatment in batch cultures with free and immobilized cells in 4% sodium alginate discs. Strains were identified as Chlorella sp and Chlamydomonas sp. Both showed good growth in MW, especially Chlamydomonas sp., which reported the highest value of kinetic growth parameters. Free Chlorella sp. culture reported one of the highest values of N-NO3- removal percentage (71.25%) and rate (0.43 mg/l/día), and the maximum values of PO43- removal parameters (83.69%; 0.09 mg/l/día) and efficacy index (EI) for both nutrients compared with Chlamydomonas sp. Immobilized cultures reported high values of nutrient removal, between 56% to 67% for N-NO3⁻ and 78% to 81% for PO43-. In most microalgae cultures, high percentages of PO43- (76-80%) were removed in 24 hours. Method of culture (free or immobilized) was the main factor affecting the nutrient removal capacity. Strains were efficient in nutrient removal in MW, especially for PO43-, with values close to the maximum ones reported for both species in previous studies.

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Lippmeier, James Casey. "Fatty acid metabolism of marine microalgae." Thesis, University of Hull, 2007. http://hydra.hull.ac.uk/resources/hull:7014.

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Pathways for the biosynthesis of docosahexaenoic acid (DHA) and other polyunsaturated fatty acids (PUFA) were elucidated in two heterotrophic, marine microalgae; Schizochytrium sp. and Crypthecodinium cohnii. PUFA-requiring auxotrophs of both of these algae were created and used as tools for studying PUFA biosynthetic pathways. Additionally, equilibrium radio-labeling techniques were applied to algal cultures fed 14C-fatty acids. Both organisms were found to possess two distinct pathways for PUFA biosynthesis. One pathway, mediated by classical elongases and desaturases, was incomplete in both organisms and was not capable of complementing PUFA auxotrophic phenotypes or of producing PUFA de novo, but could produce DHA from simpler PUFA precursors. The second PUFA pathway in each organism was desaturase and elongase independent. In C. cohnii, this pathway was distinguished by a capacity to produce DHA from acetate, in a manner similar to that of Schizochytrium which was shown to employ a polyketide synthase (PKS) complex for primary DHA biosynthesis. Additionally, genes of the Schizochytrium PUFA-PKS were successfully expressed in transgenic yeast, which produced DHA. Candidates for genes encoding C. cohnii PUFA-PKS components and other genes of C. cohnii PUFA biosynthesis were identified and discussed.

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Olofsson, Martin. "Microalgae - future bioresource of the sea?" Doctoral thesis, Linnéuniversitetet, Institutionen för biologi och miljö (BOM), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-46512.

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Unicellular microalgae are a renewable bioresource that can meet the challenge forfood and energy in a growing world population. Using sunlight, CO2, nutrients,and water, algal cells produce biomass in the form of sugars, proteins and oils, allof which carry commercial value as food, feed and bioenergy. Flue gas CO2 andwastewater nutrients are inexpensive sources of carbon and fertilizers. Microalgaecan mitigate CO2 emissions and reduce nutrients from waste streams whileproducing valuable biomass.My focus was on some of the challenging aspects of cultivating microalgae ascrop: the response of biomass production and quality to seasonality, nutrients andbiological interactions. Approach spans from laboratory experiments to large-scaleoutdoor cultivation, using single microalgal strains and natural communities insouthern (Portugal) and northern (Sweden) Europe.Half of the seasonal variation in algal oil content was due to changes in light andtemperature in outdoor large-scale cultures of a commercial strain (Nannochloropsisoculata). Seasonal changes also influence algal oil composition with more neutrallipids stored in cells during high light and temperature. Nitrogen (N) stress usuallyenhances lipid storage but suppresses biomass production. Our manipulationshowed that N stress produced more lipids while retaining biomass. Thus,projecting annual biomass and oil yields requires accounting for both seasonalchanges and N stress to optimize lipid production in commercial applications.Baltic Sea microalgae proved to be a potential biological solution to reduce CO2emissions from cement flue gas with valuable biomass production. A multi-speciescultivation approach rather than single-species revealed that natural or constructedcommunities of microalgae can produce equivalent biomass quality. Diversecommunities of microalgae can offer resilience and stability due to more efficientresource utilization with less risk of contamination, less work and cost for culturemaintenance.Stable algal biomass production (annual basis) was achieved in outdoor pilot-scale(1600 L) cultivation of Baltic Sea natural communities using cement flue gas as aCO2 source. Results indicate favorable algal oil content at northern Europeanlatitudes compared to southern European latitudes.My thesis establishes the potential of cultivating microalgae as a bioresource inScandinavia, and using a community approach may be one step towardssustainable algal technology.

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Winder, Jula Susan. "Clycosidase inhibitors from microalgae and cyanobacteria." Thesis, University of Hertfordshire, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303402.

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Kellam, S. J. "Biologically active products from marine microalgae." Thesis, University of Hertfordshire, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234360.

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MacGregor, Seona Elizabeth. "Na'+, K'+ - atpase inhibitors from microalgae." Thesis, University of Hertfordshire, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358520.

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Todisco, Églantine. "Microalgae Growth Optimization in Biofaçade Photobloreactors." Thesis, Nantes, 2019. http://www.theses.fr/2019NANT4040.

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Cette thèse a pour but général de répondre à la question suivante : Comment optimiser la culture de microalgues en façade de bâtiment ? Pour y répondre, un travail de recherche allant de l’étude du comportement biologique des microalgues, jusqu’à la modélisation et l’analyse du procédé intégré au bâtiment a été mené. Pour cela, deux souches de microalgues (Chlorella vulgaris et Haematococcus pluvialis) ainsi que différentes tailles de photobioréacteurs (PBRs) (de 1,5 à 100 litres) et de volume de culture (jusqu’à 700 litres) ont été utilisés. Cela a permis d’étudier l’évolution thermique des PBRs de façade ainsi que l’impact sur la productivité des microalgues, des cycles jour/nuit couplés à des cycles de température, du bullage et du changement d’échelle. Au final, un modèle thermique a été développé afin de prédire l’évolution de la température en fonction des conditions météorologiques et des échanges thermiques entre les différentes parties du système PBR et le bâtiment hôte. L’étude de l’impact biologique de la température a montré un lien étroit entre température et intensité lumineuse. L’intensité du bullage est apparue comme un paramètre opératoire clé, pour éviter l’accumulation d’oxygène dissout en journée et l’inhibition de la croissance, et l’anoxie la nuit, qui favorise la lyse cellulaire. En utilisant les données obtenues à échelle réelle, une analyse technicoéconomique a été réalisée, montrant les principales optimisations à apporter à cette technologie originale de production, qui s’inscrit dans une logique de transition écologique en milieu urbain
This PhD thesis has a general aim to answer the following question: How to optimize microalgae growth in façade photobioreactors (PBRs)? For that purpose, a study was undertaken, encompassing characteristics of microalgae growth and a complete analysis of the biofaçade process. Two microalgae species (Chlorella vulgaris and Haematococcus pluvialis) were studied, as well as different PBRs (laboratory and pilot scales) and culture volumes (up to 700 liters). The objective was to study the thermal behavior of the façade PBR, as well as the impact of various factors on biomass productivity, namely, day/night cycles paired with temperature cycles, bubbling intensity and scale of production. A thermal model was developed to estimate the culture temperature evolution according to weather conditions. Thermal exchanges were characterized for both, thePBR and its host building. Studying the biological impact of the culture temperature has shown a strong correlation between culture temperature and light received by the microalgae. The bubbling intensity also appeared to be a crucial operating factor, avoiding dissolved oxygen accumulations during the day which inhibits biomass growth, and preventing anoxic conditions being achieved during the night, which in turn increases the biomass decay rate. Using data obtained during full scale experiments, a technical and economic analysis wasundertaken, highlighting the main factors involved in the optimization of this new and original production technology, aiming ecological transition in urban environment

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Anthony, Renil J. "Solvent Extraction of Lipids from Microalgae." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1280854965.

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Liu, Shihong. "Harvesting and Lipid Extraction of Microalgae." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou153745894209388.

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Cheung, Kwai Chung. "Purification of landfill leachate by microalgae." HKBU Institutional Repository, 1991. https://repository.hkbu.edu.hk/etd_ra/7.

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Dissertations / Theses on the topic 'Microalgae'

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