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Petrick, Ingolf, Lilli Dombrowski, Michael Kröger, Thomas Beckert, Thomas Kuchling, and Sven Kureti. "Algae Biorefinery – Material and energy use of algae." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-137259.
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Algae offer as much as 30 times greater biomass productivity than terrestrial plants, and are able to fix carbon and convert it into a number of interesting products.
The numerous challenges in algae production and use extend across the entire process chain. They include the selection of suitable algal phyla, cultivation (which takes place either in open ponds or in closed systems), extraction of the biomass from the suspension, through to optimal use of the obtained biomass. The basic suitability of aquatic biomass for material use and energy supply has been demonstrated in a large number of studies. Numerous research projects are concerned with identifying the optimal processes to enable its widespread implementation. [... aus der Einleitung]
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Petrick, Ingolf, Lilli Dombrowski, Michael Kröger, Thomas Beckert, Thomas Kuchling, and Sven Kureti. "Algae Biorefinery – Material and energy use of algae." DBFZ Deutsches Biomasseforschungszentrum, 2013. https://slub.qucosa.de/id/qucosa%3A4316.
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Algae offer as much as 30 times greater biomass productivity than terrestrial plants, and are able to fix carbon and convert it into a number of interesting products.
The numerous challenges in algae production and use extend across the entire process chain. They include the selection of suitable algal phyla, cultivation (which takes place either in open ponds or in closed systems), extraction of the biomass from the suspension, through to optimal use of the obtained biomass. The basic suitability of aquatic biomass for material use and energy supply has been demonstrated in a large number of studies. Numerous research projects are concerned with identifying the optimal processes to enable its widespread implementation. [... aus der Einleitung]
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Young, Ashton M. "Zeolite‐Based Algae Biofilm Rotating Photobioreactor for Algae and Biomass Production." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/986.
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Alkaline conditions induced by algae growth in wastewater stabilization ponds create deprotonated ammonium ions that result in ammonia gas (NH3) volatilization. If algae are utilized to remediate wastewater through uptake of phosphorus, the resulting nitrogen loss will hinder this process because algae generally require a stoichiometric molar ratio of N16P1. Lower ratios of N/P due to loss of ammonia gas will limit the growth and yield of algae, and therefore will reduce phosphorus removal from the water phase into the algae phase. In order to reduce nitrogen loss through volatilization, an ammonium selective zeolite, clinoptilolite, can be used to sequester nitrogen from the water phase as ammonium ion and in a form that is bioavailable for uptake and growth of algae. A novel algae biofilm rotating photo bioreactor (RPB) with clinoptilolite integrated to the outermost surface as the substratum for algae biofilm attachment and growth has been designed, constructed, and tested for ammonium capture and algae biomass production, with simultaneous removal of the algal nutrient phosphorus from water. The clinoptilolite‐based RPB (cRPB) provides algal biomass that can serve as feedstock for biofuel production through uptake of zeolite‐based nitrogen and water phase phosphorus.
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Shamsudin, L. B. "The benthic algae of the River Itchen with particular reference to epilithic algae and epilithic algae on selected macrophytes." Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375372.
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Beaty, Myron H. "Cryopreservation of eukaryote algae." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-07282008-135156/.
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Baloyi, Hope. "Algae liquefaction / Hope Baloyi." Thesis, North-West University, 2012. http://hdl.handle.net/10394/8153.
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The liquefaction of algae for the recovery of bio–oil was studied. Algae oil is a non–edible feedstock and has minimal impact on food security and food prices; furthermore, it has been identified as a favourable feedstock for the production of biodiesel and this is attributed to its high oil yield per hectare. Algae oil can be potentially used for fuel blending for conventional diesel. The recovery step for algae oil for the production of biodiesel is costly and demands a lot of energy due to the high water content and size of the algae organism. In this study hydrothermal liquefaction was used for the recovery of oil from algae biomass. Hydrothermal liquefaction uses high water activity in sub–critical water conditions to convert wet biomass to liquid fuel which makes the process more cost effective than pyrolysis and gasification in terms of energy savings on biomass drying costs.
The main objective of this study was to determine suitable liquefaction reaction conditions (reaction temperature, biomass loading and reaction atmosphere) for producing bio–oil from algae and identifying the effects of these conditions on bio–oil yield and properties. Bio–oil properties are a good indication of the quality of the oil product and the significance of the liquefaction reaction conditions. The experiments were carried out in a SS316 stainless steel high pressure autoclave. An environmental scanning electron microscope with integrated energy dispersive spectroscopy was used for the characterisation of the raw algae biomass. The algae biomass was liquefied in water at various temperatures ranging from 280 to 360°C, at different biomass loadings (3 to 9 wt %) and a 5 wt% potassium hydroxide (KOH) for all experiments. The reaction time was held constant at 30 minutes in all experiments performed under CO2 and N2 atmospheres. Chloroform was used to recover the bio–oil oil from the reaction mixture following liquefaction, and the bio–oil was purified by removing chloroform using a vacuum distillation process.
The bio–oil sample was methylated to the fatty methyl esters using trimethyl sulfonium hydroxide solution to determine its composition using gas chromatography. The elemental composition of the bio–oil was analysed using a Flash 2000 organic analyser. The main organic components of the bio–oil were determined using Fourier–transform infrared (FT–IR) spectroscopy. The oil yield was found to be dependent on reaction temperature and biomass loading when liquefaction was done in an inert environment, showing a significant increase at high temperatures and biomass
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loadings. Biomass loading had no significant influence on bio–oil yields at high temperatures in a reducing atmosphere and an average oil yield of 25.28 wt% and 20.91 wt% was obtained under a CO2 atmosphere and a N2 atmosphere at 360°C, respectively. Higher yields of C16 fatty acid were obtained at 320°C at a 3 wt% biomass loading in a CO2 atmosphere. The FTIR analyses showed the presence of oxygenated compounds such as phenols, ketones, aldehydes and ethers. The bio–oil had a reduced O/C ratio as compared to that in the original feedstock, with improved heating values. The reduction in the O/C ratio in the bio–oil indicated that deoxygenation occurred during liquefaction and that the bio–oil produced has good properties for combustion. This study indicates that the bio–oil is well suited for further processing to biodiesel because of the high C16 fatty acid content. Hydrothermal liquefaction could thus be a feasible method for producing bio–oil from Scenedesmus acutus.Thesis (MSc Engineering Sciences (Chemical Engineering))--North-West University, Potchefstroom Campus, 2012.
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Watson, Anne Mary. "The filtration of algae." Thesis, University College London (University of London), 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403594.
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Croft, Martin Tom. "Vitamin B₁₂ in algae." Thesis, University of Cambridge, 2006. https://www.repository.cam.ac.uk/handle/1810/284053.
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Vitamin B12-dependent algae are unable to grow in medium made with natural filter-sterilized seawater or freshwater unless a vitamin B12 supplement is added to the culture, suggesting that the concentration of free vitamin B12 in the natural environment in generally too low to support the growth of vitamin B12-dependent algae. The source of cobalamin for algae appears to be vitamin B12-synthesizing bacteria, because when these organisms are grown in co-culture, the algae no longer require the vitamin. In return for vitamin B12, the bacteria are able to use the products of algal photosynthesis to grow, indicating an important and unsuspected symbiosis. Using the green alga Chlamydomonas reinhardtii as a model organism, RT-PCR analysis has demonstrated that vitamin B12 regulates the expression of the gene encoding the vitamin B12-independent methionine synthase. Cobalamin is likely to regulate the expression of this gene by binding directly to the mRNA and influencing its secondary structure, since affinity binding studies suggest that the mRNAs that encode for the methionine synthase proteins have a high affinity for cobalamin. Further work in C. reinhardtii and Euglena gracilis has shown that a cell wall protein is involved in the high affinity uptake of vitamin B12, since mutants deficient in cell wall biosynthesis are impaired in their ability to take up the vitamin. The C. reinhardtii protein has been purified by affinity chromatography, and identified by mass spectrometry. The complete cDNA encoding the C. reinhardtii vitamin B12 binding protein has been cloned, and the protein shown to be a member of the pherophorin family, a well-known group of green algal cell wall proteins. A combination of techniques has indicated that the protein is glycosylated, and that the sugar moieties are attached to a central domain that contains a significant number of hydroxyproline residues.
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Henderson, Rita Kay. "PosiDAF for algae removal." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/4472.
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During algac blooms, coagulation is frequently unsuccessful resulting in poor flotation duc to complex algal character. 11iis thesis cxplorcs tlic link between algal character and conventional treatment and the potential for developing morc appropriatc algac trcatmcnt tcclinologics. Specifically, dissolvcd air flotation (DAF) that has bccn adaptcd by dosing cationic clicmicals to the saturator to modiry bubbic surfaccs, such that it docs not rcly on coagulation, is invcstigatcd. 1'his proccss is tcrmcd PosiDAF. Analysis of dissolved algogcnic organic mattcr (AOM) extracted from problcmatic species enabled investigation of the impact of morphology and AOM on coagulation- flocculation-flotation. Both increasing surface area and charge density of algae systcrns, werc rclatcd to increasing coagulant dcmand. Application of the appropriate coagulant dcmand ensured removal of all thrcc components - cclls, AOM and coagulant. Maintaining the zcta potential bct-%vccn -10 mV and +2 mV ensured optimum rcmoval was obtained. PosiDAF trials were conducted by dosing chemicals that had previously been shown to alter bubble charge, including co3gulant, surfactant and polymer, to the saturator. Coagulants were unsuitable for use in PosiDAF as they did not remain at the bubble surface. Highly hydrophobic, cationic surfactants were observed to remove cells according to a theoretical model, such that removal improved with increasing bubbic: particic ratio and with cell size. The polymer, polyDADNIAC, achieved greater removal cfficiencies than those predicted theoretically, attributed to an increase in the swept volume of the bubble. However, polyDADMAC was sensitive to changes in AOM composition. A chemical that combines attributes of both surfactant and polyDADMAC may overcome the barriers to PosiDAF implementation.
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Vinikoor, Conner Reid. "Life History of Volvocine Algae." Thesis, The University of Arizona, 2010. http://hdl.handle.net/10150/146595.
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The evolution of somatic cells is a key aspect in the evolution of single to multicellular life forms. Our model is based on an empirically tested model of the growth of unicellular Chlamydomonas algae and a suggestion by Koufopanou (1994) that the basic mechanism underlying Chlamydomonas growth and reproduction may better explain the diversity of more complex volvocine algae morphologies. Six strains of Pleodorina starrii investigated in terms of the parameters of the model, yielded data for the proportion somatic (p) at various cell number sizes.
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Emil, Axelsson. "Up-scaling of algae cultivation." Thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-60493.
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Microalgae are one of the oldest types of lifeforms on this planet and dead algae are one source for the oil that we extract from the ground. This oil has a major part in the technology advances of humanity, to levels unimaginable not long ago. Unfortunately, this oil is one of the major reasons for the global warming and other environmental issues caused by humans. Therefore, much effort is made on new technologies to decrease the use of fossil oil and other fossil material in favor for so called renewable sources. In this work focus is on production of biomass that can be used for processing to other bulk materials, mainly chemicals. This is also a highly potential market, the amount of materials derived from fossil sources are at least 422 million metric tons per year. The issue though is that the production costs for algae are still fairly high and can’t compete with the market price of fossil raw materials. Two algae species, Scenedesmus obliquus and Coelastrella sp., were cultivated in 6 pilot size ponds (500 L) and the results were compared to a lab experiment (0.5 L). The lab experiment was earlier performed by the author’s supervisors with the same species. The algae in the ponds were cultivated outdoor with flue gas in semi-closed ponds and the resulting biomass was allowed to sediment spontaneously. Scenedesmus obliquus was successfully cultivated in the pilot, but the system was not suitable for cultivation of Coelastrella sp. The main aim of this work was to evaluate if it is possible to predict the amount of biomass produced in the pilot cultivation based on the results from the previously performed lab cultivation. The conclusion based on the results in this work is that it not possible to predict the biomass production in the pilot based on lab experiments. The properties and behavior of different algae species can be very different in different systems, and the setups in this study differed too much. However, the results indicate that the pilot system has a high efficiency and can maintain a monoculture outdoors for at least 18 days as well as that the supply of flue gas highly affects the growth of the algae Scenedesmus obliquus.
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Ress, Jennifer Ann. "The Ecology of Aerial Algae." Bowling Green State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1332874801.
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Bosley, Amber L. "Algae Characterization and Processing Techniques." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1321538296.
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Girme, Gauri Manik. "Algae powered Microbial Desalination Cells." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397735584.
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Cherad, Ramzi. "Supercritical water gasification of algae." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/11442/.
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Diversification of our energy supplies – especially in the transport and electricity generation sectors – is required to meet decarbonisation targets. Algae have been identified as suitable alternative feedstocks for third generation biofuels due to their fast growth rates and non-competitiveness with land for food crops. Hydrothermal processing of algae is an appropriate conversion route as it allows the processing of wet feedstock thus removing the energy penalty of drying. In this study, supercritical water gasification was used for (i) the hydrothermal processing of macroalgae for the production of gaseous fuel – mainly hydrogen and methane – and (ii) the upgrading of the process water from hydrothermal liquefaction of microalgae for hydrogen production for biocrude hydrotreating. The supercritical water gasification (SCWG) of the four macroalgae species investigated (Saccharina latissima, Laminaria digitata, Laminaria hyperborea, and Alaria esculenta) produced a gas that mainly consisted of hydrogen, methane and carbon dioxide. Non-catalytic SCWG resulted in hydrogen yields of 3.3-4.2 mol/kg macroalgae and methane yields of 1.6-3.3 mol/kg macroalgae. Catalytic SCWG (using ruthenium) resulted in hydrogen yields of 7.8-10.2 mol/kg macroalgae and methane yields of 4.7-6.4 mol/kg macroalgae. The yield of hydrogen was approximately three times higher when using sodium hydroxide as catalyst (16.3 mol H2 / kg macroalgae) compared to non-catalysed SCWG of L. hyperborea (5.18 mol H2 / kg macroalgae). The energy recovery (an expression of how much chemical energy of the feedstock is recovered in the desired product following hydrothermal processing) was 83% when sodium hydroxide was used as a catalyst, compared to 52% for the non-catalytic SCWG of L. hyperborea. The yield of methane was approximately 2.5 times higher (9.0 mol CH4 kg 1macroalgae) when using ruthenium catalyst compared to the non-catalysed experiment (3.36 mol CH4 / kg macroalgae) and the energy recovery increased by 22% to 74%. The selectivity of methane or hydrogen production during the SCWG of macroalgae can be controlled using ruthenium or sodium hydroxide respectively. Longer hold times and increased reaction temperature favoured methane production when using ruthenium. An increase in catalyst loading had no significant effect on the methane yield. Higher hydrogen yields were obtained through using higher concentrations of sodium hydroxide, lower algal feed concentration and shorter hold times (30 min). Increasing reaction times ( > 30 min) with a base catalyst (sodium hydroxide) decreased the hydrogen yield. Overall energy recovery was highest at the lowest feed concentrations; 90.5% using ruthenium and 111% using sodium hydroxide. The process waters from the hydrothermal liquefaction (HTL) of microalgae (Chlorella, Pseudochoricystis, and Spirulina) were gasified under supercritical water conditions to maximise hydrogen production. Hydrogen yields ranged from 0.18-0.29 g H2 / g biocrude from SCWG of the process water of HTL along with near complete gasification of the organics (~98%). Compared to the hydrogen requirements for hydrotreating algal biocrude (~0.05 g H2 / g biocrude), excess hydrogen can be produced from upgrading the process water through SCWG. The results indicate that process waters following SCWG are still rich in nutrients that can be recycled for algal cultivation.
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Whitton, Rachel Louise. "Algae reactors for wastewater treatment." Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/10289.
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The onset of the Water Framework Directive (WFD) will challenge water utilities to further reduce their wastewater phosphorus discharges to < 0.5 mg.L- 1. Whilst conventional treatments, such as chemical dosing, are able to meet these new discharge consents, the strategies are representative of a linear economy model where resources are unrecovered and disposed. An alternative solution which can contribute to the aspiration of a circular economy is microalgae. Microalgae are ubiquitous in wastewater environments and assimilate phosphorus during their growth, to residual concentrations complementary of the WFD. Furthermore, microalgal biomass can be anaerobically digested to produce biomethane offering the potential for an energy neutral approach. However, uptake of microalgal systems are lacking in the UK through limited knowledge of operation; and the belief that such solutions are synonymous to large, shallow open ponds with extensive treatment times. The development of alternative microalgal reactors are increasingly investigated to overcome these implementation challenges. Of these, immobilised microalgae has shown great potential; and whilst within its infancy demonstrates the greatest opportunity for development and optimisation. This thesis determines the critical operational parameters that influence the remediation efficacy of immobilised microalgae for tertiary nutrient removal; including species selection, biomass concentration, treatment period and lighting; with recommendations for optimal performance. These recommendations are then applied to the design and operation of an immobilised bioreactor (IBR) to understand the key design and operating components that influence the overall economic viability. In doing so, the potential for an IBR to be economically viable, within the next decade, in comparison to traditional approaches are discussed.
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Zacher, Katharina. "Effects of UV radiation on Antarctic benthic algae : with emphasis on early successional stages and communities = Effekte von UV-Strahlung auf antarktische benthische Algen : mit schwerpunkt auf jungen Entwicklungsstadien und Gemeinschaften /." Bremerhaven : Alfred-Wegener-Institut für Polar- und Meeresforschung, 2007. http://www.loc.gov/catdir/toc/fy0804/2008422507.html.
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Kaehler, Sven. "Causes and consequences of the spatial and temporal distribution of encrusting algae on tropical rocky shores." Thesis, Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B17505616.
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Lees, Fiona M. "Studies on metal-tolerant estuarine algae." Thesis, Heriot-Watt University, 1985. http://hdl.handle.net/10399/1620.
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Ball, Lucy Ann. "Carbon acquisition in the chrysophyte algae." Thesis, University of Dundee, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403161.
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Patel, Bhavish. "Wet algae processing for biofuel production." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/62984.
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Microalgae is seen as a sustainable source of chemicals and biofuels, but its processing to low value fuels is expensive, particularly due to drying, and thus the feasibility of a wet processing route is necessary. This thesis presents experimental research and life cycle assessment on the conversion of microalgal biomass to liquid biofuel (precursor) using high temperature and pressure processing technologies. The bulk of the work is related to Hydrothermal Liquefaction of algal biomass at various residence time (0.5 - 60 min) and temperatures within the Hydrothermal regime (275 - 380°C), using both batch and novel in-house built continuous flow reactor systems. Several analytical tools were deployed to assist with analysis of the formed biocrude to help understand the effect of the reaction conditions on the formed products. Having analysed the biocrude, it became apparent that the aqueous phase contained substantial matter and as such an investigation to quantitate the inorganics in the aqueous phase was conducted. As for the biocrude, detailed analysis showed that further treatment was necessary to make it amenable for utility directly or as a blended fuel and thus, Hydrotreatment using commercially available catalyst under H2 in a batch reactor was conducted. Lastly, the conversion of algal lipids to biodiesel as well as other constituents was investigated under Hydrothermal conditions in presence of methanol, leading to in situ Supercritical Transesterification. The reaction conditions used were found to be too severe for stable yield of methyl esters and consequently degradation kinetics of methyl esters was calculated. Lastly, to understand the environmental profile of the investigated processes, a life cycle assessment was conducted based on experimental data combined with literature values for a conceptual biorefinery in 5 different countries with differing energy mixture. The thesis ends with concluding remarks on the investigation and potential direction for future work.
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O'Rourke, Christina Margaret. "Cell wall polysaccharides in charophytic algae." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/17868.
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Plants colonised land 460 million years ago and charophytes represent the closest living relatives of land plants. The ability to live on land may depend on the presence of certain cell wall polysaccharides such as xyloglucan, a hemicellulose exclusively found in land plants (Popper and Fry, 2003). The cell walls of charophytes are poorly characterised. The aim of this project was to use biochemical techniques to characterise the cell wall polysaccharides of charophytic algae in relation to early land plant phylogeny. Hydrolysis of Coleochaete scutata and Chara vulgaris cell walls in 2 M trifluoroacetic acid yielded predominantly GalA, Gal, Glc and Man residues and also some Ara, Xyl and traces of Fuc and Rha. In addition, hydrolysis of Chara pectin revealed an abundance of an unusual monosaccharide, 3-O-methyl-D-galactose, which was structurally identified by a series of 1-D and 2D NMR spectroscopy by COSY, TOCSY, NOESY and HSQC. 3-O-Methyl-D-galactose is more commonly found in lycophyte cell walls where its presence has been suggested to be related to lycophytes’ evolutionarily isolated position (Popper et al., 2001). The newly discovered presence of 3-O-methyl-D-galactose in charophyte pectin suggests that this polymer may be more complex than previously thought. Coleochaete and Chara hemicellulose extracts were fractionated by anion-exchange chromatography into five classes. A strongly anionic fraction from Chara hemicellulose was found to be rich in Glc, Xyl, Gal and Fuc suggestive of a xyloglucan-like polysaccharide. However, XEG was unable to produce diagnostic xyloglucan oligosaccharides in either Coleochaete or Chara hemicelluloses. Xylanase and mannanase digestion of Coleochaete and Chara hemicelluloses gave xylan- and mannan-oligosaccharides. Furthermore, lichenase digestion of Coleochaete hemicellulose yielded an unusual octasaccharide composed of approximately equimolar xylose and glucose. My work has shown that charophyte cell walls are a source of undiscovered monosaccharides and potentially novel pectic and hemicellulosic domains which may have important functions in enabling the successful colonisation of land by plants.
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Ayarza-León, Jorge Luis. "Alginates: 20000 applications of submarine algae." Revista de Química, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/100618.
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Desde la antigüedad, el ser humano ha encontrado recursos de gran utilidad en el mar. Las algas pardas marinas de la clase Phaeophyceae son la fuente de un biopolímero con propiedades muy interesantes, denominado alginato. En la actualidad, el alginato es extraído y comercializado en muchos lugares del mundo, es un componente importante en muchos productos de uso diario, e incluso se le emplea a nivel de investigación académica.Since antiquity, mankind has depended on the sea to obtain valuable resources. Marine brown algae from the class Phaeophyceae are the source of a biopolymer with very interesting properties called alginate. Nowadays, alginate is extracted and commercialized around the world, it is an essential component in many everyday products, and it is even used in academic research.
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Hong, Yu. "Microwave-enhanced thermal processing of algae." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/46682/.
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Algae are promising substitutes to the widely-used fossil fuels. The thermochemical conversion of algae has been investigated extensively in the past two decades. In this study, systematic investigation of microwave-enhanced pyrolysis of algae together with catalytic reforming was conducted aiming at developing a new approach for the production of more syngas-enriched gas product from algae and other marine biomass. Firstly, the characterisation of algae was conducted to show the nature of the raw materials followed by the kinetic study of the decomposition of a suite of micro- and macro-algae, i.e., spirulina, chlorella and porphyra. The kinetic study was carried out using model algae, i.e. the use of ovalbumin as protein, oil droplets as lipid and cellulose as polysaccharides or carbohydrate to simulate a real alga. The thermogravimetric characteristics of algal samples were studied based on the analysis of TG and DTG curves. Kissinger-Akahira-Sunose method was used to derive the activation energy and pre-exponential factor. Moreover, the optimal reaction mechanism was determined by using Coats-Redfern method of the decomposition of different samples. The morphology and composition of char after TG analysis were characterised by using SEM/EDS. By comparing the characteristics of chars prepared in N2 and CO2 atmosphere, it was found that CO2 atmosphere favored the pyrolysis of algal protein with lower required activation energy (about 235 kJ mol-1) and shortened the pyrolysis time by 5.9-20.2%. But it was also found that the algal lipid increased the difficulty for the pyrolysis of algae with relatively higher activation energy around 200 kJ mol-1 (>180 kJ mol-1 under N2). However, the activation energy of cellulose decomposition remained almost the same around 310 kJ mol-1 in N2 and CO2. Therefore, CO2 atmosphere is more suitable for the pyrolysis of algae with high protein content and low lipid content. It was also found that protein in algae decomposes first, which is followed by the decomposition of carbohydrates and then lipids. Secondly, in order to obtain a high yield of syngas-enriched gas product from algae, microwave-enhanced pyrolysis of algae (spirulina, chlorella, dunaliella, laminaria and porphyra) and primary model algal compounds, i.e. cellulose and ovalbumin, at 400, 550 and 700°C in N2 atmosphere was conducted. The distribution and composition of gaseous, liquid and solid products were also studied in detail. Amongst the five algae, porphyra is the most promising raw material for high syngas-enriched gas production with more than 85 wt.%, while protein-rich spirulina and chlorella favored bio-oil production which yielded in about 10 wt.%. Meanwhile, with 94 wt.% carbohydrate, dunaliella converted most of its carbohydrates into C1-C3 gases. With a high portion of incombustible components (14.7-23.3 vol.% of CO2), laminaria has relatively lower gaseous production which was less than 80 wt.%. It also found that the optimal pyrolysis temperature was in the range of 400 to 550 °C for most of the samples except for spirulina which was at 700 °C. For the production of bio-oil, microalgae, with high protein content, were favored to be the raw materials (oil yield of 5.2-15.4 wt.%), compared to macroalgae (oil yield of 1.8-5.2 wt.%). Moreover, microalgae- spirulina and chlorella-favoured the formation of more phenols and nitrogenated compounds (10.8-17.8% and 20.9- 28.7% respectively) primarily from protein content, while less PAHs of 11.4-29.9% which mainly derived from algal carbohydrates. Finally, microwave-enhanced reforming of algae under CO2 atmosphere was conducted at 400, 550 and 700°C, together with the comparison of the results including the distribution and composition of gas, bio-oil and char in N2 and CO2 atmospheres. Compared with the product distribution derived under N2, the bio-oil yield from most algae in CO2 increased by 50- 170%, whilst the production of gas slightly decreased by 1-7%. Under CO2 atmosphere, the syngas in spirulina and chlorella gas product dramatically decreased by 60.8-69.7% and 7.1-17.6% respectively, while that from dunaliella increased by 23.4-30.4%. The percentage of syngas for the other samples remained similar. For the bio-oil derived from all the five algae samples, there were nearly no PAHs contained. In addition, the ash of algae was used as catalyst and introduced into the pyrolysis of five algae respectively under N2 atmosphere at 550°C. Compared with the non-catalytic pyrolysis, the weight percent of char from most algae increased by 20-90% using laminaria and porphyra ash, due to the decomposition of compounds in bio-oil. The syngas percentage from microalgae significantly increased by 6-45%, while that from macroalgae slightly decreased by 2-15% with the addition of spirulina, chlorella and porphyra ash. The content of PAHs in the bio-oil of spirulina, chlorella, laminaria and porphyra considerably reduced by 29-94%, while the amount of aromatics from spirulina and chlorella increased to around 1.3-7.1 times. In summary, the microwave-enhanced pyrolysis of algae favored the production of more CO/H2 rich gas at lower pyrolysis temperature under N2 atmosphere, while under CO2 atmosphere the yield of bio-oil increased. With the addition of algal ash as catalysts, the CO+H2 percentage in gas production from microalgae increased significantly. Therefore, it can be concluded that the microwave-enhanced pyrolysis of algae is an effective and efficient process for the conversion of algal biomass into value-added fuels.
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Foltz, Garrett. "Algae Lysis with Pulsed Electric Fields." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/732.
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With growing interest in alternative fuels, algae lipid harvesting is seen as a possible source of biofuel. Algae species under consideration include Chlorella vulgaris, Chlamydomonas reinhardtii and Dunaliella salina due to lipid contents as high as 30% to 56% of their dry weight (depending on growth conditions) and availability [5], [6]. In order to harvest lipids from algae, the cells must first be lysed.
Lysing is achieved by breaking the algal cell wall or membrane to separate oil from the rest of the algae biomass. Current lysing procedures use enzymes, pressure homogenization, and/or sonication to lyse cells; however, these methods are costly and complicate oil extraction [9], [10].
This project examines a novel method of cell lysis through pulsed electric field (PEF) application that enables cost-effective extraction methods relative to current enzyme and sonication techniques.
A theoretical model for cell membrane potential in the presence of electric field was developed, and PEF chambers were manufactured on microscope slides to enable microscope viewing and cell lysis recording during PEF application. Additionally, larger static chambers were created for testing higher volumes of algal solution. Electric field characteristics, such as pulse width, pulse number and magnitude, sufficient for lysis of Dunaliella salina and Chlorella vulgaris were found.
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Venkatagiri, Avinash. "Materials and Methods for Algae Preconcentration." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1406313094.
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Evans, C. "Molecular phylogeny of glaucocystophyte and other algae using hemB : aminolaevulinic acid dehydratase in algae is magnesium-requiring." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598897.
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The glaucocystophyte algae contain simple plasmids, in common with red and green algae and higher plants. Although these groups have been shown to be monophyletic, the phylogenetic position of the latter is uncertain. The nuclear-encoded locus hemB, which encodes aminolaevulinic acid dehydratase (ALAD), was chosen to examine the phylogeny of the algae. ALAD occurs in organisms as either of two generalised classes; in most eubacteria, animals and fungi the enzyme requires Zn2+ for full activity, in plants and green algae Mg2+ is required. A sequence motif indicates which form of the enzyme is encoded by hemB. Sequence information was also collected for the algae for another nuclear gene GapC, which encodes the cytosolic form of glyceraldehye-3-phosphate dehydrogenase, for phylogenetic analysis and subsequent comparison with the hemB trees. A biochemical survey of the algae was carried out for ALAD, which indicated that most algae contain a Mg-binding ALAD. However the assay was unsatisfactory for some taxa and it was not possible to determine which kind of ALAD they possess. These initial results were then supplemented with sequence data for hemB in a number of different algae. Full and partial sequences were obtained from glaucocystophyte, red and brown algae and where this sequence included the metal-binding site, this always indicated a Mg2+ requirement for ALAD. The position in the trees of bacteria with a Mg-binding ALAD relative to the algae, suggests that horizontal gene transfer may have been the mechanism by which plants and algae obtained a Mg-binding ALAD.
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Lekan, Danelle Kara. "Influence of temperature, salinity and nutrients on growth and toxin of Karenia brevis clones." View electronic thesis, 2008. http://dl.uncw.edu/etd/2008-2/r3/lekand/danellelekan.pdf.
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Almeida, Linoberg Barbosa de. "Sistema Mundial, Mercosul e Alca." Florianópolis, SC, 2004. http://repositorio.ufsc.br/xmlui/handle/123456789/88062.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas. Programa de Pós-graduação em Sociologia PolíticaMade available in DSpace on 2012-10-22T05:14:48Z (GMT). No. of bitstreams: 0
O objetivo principal deste trabalho é analisar como se dá a continuidade da consolidação do Mercosul, a ampliação das relações com a União Européia e o momento de formação da ALCA (Área de Livre-Comércio das Américas) no conjunto da política externa brasileira. Isto é, como desenvolve-se o processo decisório baseado em possibilidades de integração a uma economia globalizada que contempla basicamente econômicos deixando em segundo plano aspectos como soberania e legitimidade. A partir do cenário em questão e de conceitos como hegemonia, sistema-mundo e imperialismo, discutimos a possibilidade para que se construa uma nova composição de forças que possibilitem uma outra orientação política fruto da vontade coletiva resultando lutas sociais que gerem ações políticas diferentes das presentes atualmente nos discursos do governo brasileiro. Para tanto, encontra-se aqui: uma análise das transformações do sistema mundial e seus elementos determinantes como riqueza, Neoliberalismo, globalização e o papel de algumas instituições internacionais e dos Estados Unidos; alguns aspectos sobre as teorias de integração; a importância de uma projeto de Mercosul; e algumas questões relevantes sobre os governos Cardoso e Lula no constante avanço e retrocesso da política externa brasileira sujeita as vontades do mercado.
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Gabel, Jennifer E. "Phylogenetic reassessment of the mastophoroideae (Corallinaceae, rhodophyta) using molecular and morphological data /." Electronic version (PDF), 2003. http://dl.uncw.edu/etd/2003/gabelj/jennifergabel.pdf.
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Bischoff-Bäsmann, Bettina. "Der Temperaturbedarf und Biogeographie mariner Makroalgen." Bremerhaven : Alfred-Wegener-Institut für Polar- und Meeresforschung, 1992. http://catalog.hathitrust.org/api/volumes/oclc/54346279.html.
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Carter, Alan Robert. "Studies on the biology of the economic marine red alga Gelidium pristoides (Turner) Kuetzing (Gelidiales : Rhodophyta)." Thesis, Rhodes University, 1987. http://hdl.handle.net/10962/d1004774.
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Various aspects of the biology of the intertidal agarophyte, Gelidium pristoides, were investigated, with the aim of providing information that would assist in formulating a management policy for this economic seaweed resource. G.pristoides occurs as tufts comprising as many as 40 individual plants, representing all three conspicuous life history stages, that are linked by the intertwining of their basal creeping axes. Individual plants consist of a system of branched creeping axes, which is largely responsible for colonizing surrounding substrata, from which one or more erect flattened fronds arise. These erect fronds may reach a height of 15 cm, and are irregularly bipinnately branched. Internal vegetative anatomy is generally typical of the genus. Morphological variation in mature plants is limited to increased plant height and branch density during the summer season. A dorso-ventrally flattened creeping habit was seen during early recruitment on flat rock surfaces and limpet shells within grazer exclusion plots, which developed into typical erect plants. Although there is a close taxonomic affinity between G.pristoides and the low-growing Gelidium turf, which occurs on wave-cut platforms in the eastern Cape (both produce bispores), the turf appears to represent a genetically divergent ecotype of the typical G.pristoides habit. In the light of present observations, it is suggested that the recent inclusion of G.pristoides in the new Onikusa genus should be questioned. Reproduction in G.pristoides is typical of the genus, except for the production of bispores, instead of tetraspores, in the sporophyte generation. The smaller nuclei in the binucleate bispores, in comparison to carpospores, suggested they are the product of normal meiosis (meiospores). This was confi rmed by chromosome counts of germl i ngs deri ved from bispores (n = 13-17) and carpospores (2n = 28-33). Throughout the geographical range of the seaweed, the bisporophyte generation is dominant over the combined male and female gametophyte generati on by a ratio of about 3 : 1. This imbalance may be due to bispores. G.pristoides a greater germination success of carpospores over plants are fertile throughout the year, while at Port Alfred there is no apparent seasonality in spore release. Growth of carpospore and bispore germlings is similar under various temperature treatments in culture. Optimum temperatures for growth were from 15-23°C, which corresponds with the sea temperatures experienced within the geographical range of the species . At Port Alfred, growth (linear frond elongation) and standing crop levels were maximal during summer . Ory weight levels were significantly inversely related to both growth and ash levels. Agar contents (% of dry weight) were generally greater in summer (48% ) than in winter (30%), and were inversely correlated with thallus nitrogen levels. Agar contents of distal plant halves were higher (8-15%) than in proximal halves. Regrowth of G.pristoides to original biomass or standing crop levels after harvesting, is similar for plucking and shearing at different times of the year. Regrowth is more rapid after spring and summer harvests (2-3 months) than after winter harvests (4-5 months). During the summer season, harvesting at monthly intervals showed significantly greater total yields, and production rates (e.g . 3.13 g. dry wt. / m2 / day for plucking) than under 3-monthly intervals (1.42 g. dry wt. / m2 / day for plucking). In contrast, average yields per harvest were Significantly greater when recovery period was longer (e.g. 3 months). Quadrats that were completely denuded failed to recover after a year, while regrowth was also retarded with increased elevation on the shore. Agar contents did not differ Significantly between plucked (38%) and sheared (42%) plant material. G.pristoides is distributed from about 0 . 2-0.75 m above MLWS, with a reduction in stature and frequency corresponding to increased elevation on the shore. Frond elongation rates, germling survival and recruitment within grazer-exclusion plots, is retarded with increased elevation level. Plants transplanted above the normal vertical range of the seaweed became severely bleached and died, while plants transplanted below the normal range of the seaweed (sub littoral fringe) senesced due to overgrowth by the epiphytic encrusting coralline, Polyporolithon patena (Hook . et Harv . ) Mason . G.pristoides recrui t ment in the sublittoral fri nge was enhanced with the exclusion of grazers . However, successful recruits were displaced due to smothering by articulated corallines (e.g. Corallina sp. and Jania sp. ) . G.pristoides is largely restricted to cracks and crevices in the rock, and also occurs on a large proportion of the available shells of the limpet Patella oculus Born., and to a lesser extent, shells of the barnacle Tetraclita serrata. G.pristoides recruitment was significantly enhanced by the exclusion of grazers (using toxic antifouling paint barriers). G.pristoides recruitment within the exclusion plots was significantly greater on artificially attached limpet shells (almost 100% cover) than on rock surfaces (20-30% cover), which occurred largely within cracks and crevies in the rocky substratum. ly attached to limpet G.pristoides plants are significantly more strongand barnacle shells than to rock and epilithic encrusting corallines (Lithothamnion sp.). Removal of G.pristoides from limpet shells revealed pits of a uniform size in the surface of the shells, into which the rhizoidal attachment organs of the seaweed penetrate. It is concluded that the horizontal distribution of G.pristoides is largely controlled by grazers (and "escapes" from grazing) and resistance to dislodgement by wave action. Based on present results, and considering some of the socio-economic factors associated with the Gelidium industry in South Africa, suggestions are made concerning the management and long-term maintenance of G.pristoides resources in the eastern Cape.
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Chairopoulou, Makrina Artemis [Verfasser]. "Particle production by algae / Makrina Artemis Chairopoulou." Düren : Shaker, 2020. http://d-nb.info/1222395983/34.
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MacDonald, Hazel. "Heavy metal tolerance in filamentous green algae." Thesis, University of the West of Scotland, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329824.
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Miqdadi, Issam Mahmoud Ahmad. "Removal of algae from facultative pond effluent." Thesis, University of Newcastle Upon Tyne, 1992. http://hdl.handle.net/10443/475.
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Wastewater stabilization ponds have gained popularity as a means of secondary wastewater treatment because of their low cost and simplicity of operation and maintenance, in addition to several other advantages. However, the presence of algae in the effluent from facultative ponds may cause undesirable environmental impacts, such as DO depletion or eutrophication, in water bodies to which this effluent is discharged. Thus, regulations and/or the adverse environmental impacts of effluents containing algae sometimes necessitate reduction or removal of algae from pond effluents. Many methods have been used for the purpose of removal of algae from wastewater stabilization pond effluent. Upflow rock filtration and coagulationsedimentation have been investigated in this research. In the past, mechanisms of removal of algae in rock filters and factors that affect the removal process have not been well explained. Design of these filters has not been related mathematically to the operating variables. Three pilot rock filters were built for the purpose of this research. The first filter was filled with rock of 1 cm average diameter, the second and third filters were filled with 5 cm and 10 cm average diameter rock, respectively. Five different hydraulic loadings were applied to these filters, with variable influent characteristics and under different environmental conditions. The results of this research have shown that gravitational settling and hydrodynamic forces are the most important mechanisms affecting removal of algae in upflow rock filters. Also, a method of design of unisize-media upflow rock filters for removal of algae from facultative pond effluent has been established. The cost of coagulant has been the main disadvantage of the process of coagulation-sedimentation for algae removal from wastewater stabilization pond effluent. In this research, jar tests were carried out to determine the effect of settling time and/or addition of kaolinite or bentonite with the primary coagulant, alum, on the optimum dose of this primary coagulant required for removal of algae from facultative pond effluent. Both increase in settling time and coagulant aids, namely kaolinite and bentonite, have reduced optimum alum dose. Kaolinite and bentonite, applied as low-cost primary coagulants, were also effective in removing algae from facultative pond effluent. From the very limited experiments carried out at the end of this research, it was shown that crossflow microfiltration has some potential as a process for algae removal from facultative pond effluent. A mathematical model has been developed in this work to describe the eutrophic state of King Talal Reservoir in Jordan. The model predicts that even elimination of phosphorus from the effluent of Al-Samra Wastewater Stabilization Ponds will not bring the reservoir into an oligotrophic state.
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Xu, Simin, and 徐思敏. "Characterization of astaxanthin accumulation in green algae." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43278553.
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Figueiredo, Marcia Abreu de Oliveira. "Susceptibility of crustose coralline algae to epiphytes." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333254.
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Xu, Simin. "Characterization of astaxanthin accumulation in green algae." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43278553.
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Kampfe, Sara Katherine. "Processing and Conversion of Algae to Bioethanol." W&M ScholarWorks, 2010. https://scholarworks.wm.edu/etd/1539626902.
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Mabande, Edmund Rufaro. "Antimicrobial discovery from South African marine algae." University of the Western Cape, 2018. http://hdl.handle.net/11394/6592.
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>Magister Scientiae - MScAntimicrobials are chemical compounds that destroy or inhibit the growth of microorganisms. The majority of these antimicrobials are actually natural products or natural product derived with key examples being the pioneer antibiotics penicillin and cephalosporin. Antimicrobials are an extremely important class of therapeutic agents; however, the development of drug resistance and slow pace of new antibiotic discovery is one of the major health issues facing the world today. There is therefore a crucial need to discover and develop new antibacterial agents. In this study, the potential of marine algae as a source of new antibiotics was explored. Crude organic extracts and chromatographic fractions obtained from small-scale extraction of 17 different marine algae were used to prepare a pre-fractionated library that would be tested against several disease causing microorganisms. The activity of the pre-fractionated library and purified compounds was determined against a panel of drug resistant microorganisms namely Acinetobacter baumannii ATCCBAA®-1605™, Enterococcus faecalis ATCC® 51299™, Escherichia coli ATCC® 25922™, Staphylococcus aureus subsp. aureus ATCC® 33591™ and Candida albicans ATCC® 24433™. Finally, cytotoxicity tests of 50 selected library extracts and isolated compounds were done against two cell lines namely MCF-7 (breast cancer) and HEK-293 (kidney embryonic). Based on their antimicrobial activity and interesting chemical profiles, the seaweeds Plocamium sp. and Stypopodium multipartitum were selected for further study. Three new and unusual halogenated monoterpenes (4.16, 4.17 and 4.18) were isolated from Plocamium sp., and an unusual meroditerpenoid (5.8) was isolated from Stypopodium multipartitum. The metabolites were purified using preparative (silica gel) chromatography as well as semipreparative normal phase HPLC. The structures of purified compounds were determined from spectroscopic data, including nuclear magnetic resonance (NMR) spectroscopy. A small library of 153 fractions was generated from collections of South African marine algae. Pre-fractionated crude extracts showed excellent antimicrobial activity against all microbes but particularly against Staphylococcus aureus. The compounds were generally active against the Gram positive bacteria and the yeast. In conclusion, three antimicrobial halogenated monoterpenes and an unusual monoterpene were isolated from a Plocamium sp. and Stypopodium multipartitum respectively. Antimicrobial activity of crude fractions was excellent but that of isolated compounds was not as great as anticipated.
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Lowell, Christina, and Christina Lowell. "Thermo-acidophilic Algae: pH and Metal Tolerances." Thesis, University of Oregon, 2012. http://hdl.handle.net/1794/12361.
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The class Cyanidiophyceae (the "cyanidia") includes three genera, the walled Cyanidium and Galdieria and the "naked" Cyandioschyzon. All of these algae are unicellular and asexual and live at high temperature and low pH. The cyanidia grow optimally at a pH of 2-3 but can tolerate a higher pH and lower their surrounding pH if it is above the optimal level. They can also tolerate high concentrations of potential toxins that are often found in their natural environments. This thesis shows that strains of cyanidia from Yellowstone National Park and other geographic locations have differing abilities to lower their surrounding pH and tolerate environmental toxins that are found in many environments in which they live. These unique characteristics of this class of algae allow them to be optimally adapted for life in extreme environments with few
competitors.
This thesis includes unpublished co-authored material.
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Dong, Kanjicai. "Enhanced Oil Recovery Investigation Using Algae Polymers." Thesis, University of Louisiana at Lafayette, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10163342.
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After primary and secondary recovery there is still oil remaining in the reservoir, so tertiary recovery is introduced. This is also known as EOR. Enhanced oil recovery has been widely used with different types of polymers. Algae polymer is a new development with its own advantages and limitations. In order to discover the economic potential of algae polymer, this paper focuses on the recovery factor of algae polymer and compares it with other published results.
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Rufaro, Mabande Edmund. "Antimicrobial discovery from South African marine algae." University of the Western Cape, 2018. http://hdl.handle.net/11394/6529.
Full textAbstract:
>Magister Scientiae - MScAntimicrobials are chemical compounds that destroy or inhibit the growth of microorganisms. The majority of these antimicrobials are actually natural products or natural product derived with key examples being the pioneer antibiotics penicillin and cephalosporin. Antimicrobials are an extremely important class of therapeutic agents; however, the development of drug resistance and slow pace of new antibiotic discovery is one of the major health issues facing the world today. There is therefore a crucial need to discover and develop new antibacterial agents. In this study, the potential of marine algae as a source of new antibiotics was explored. Crude organic extracts and chromatographic fractions obtained from small-scale extraction of 17 different marine algae were used to prepare a pre-fractionated library that would be tested against several disease causing microorganisms. The activity of the pre-fractionated library and purified compounds was determined against a panel of drug resistant microorganisms namely Acinetobacter baumannii ATCCBAA®-1605™, Enterococcus faecalis ATCC® 51299™, Escherichia coli ATCC® 25922™, Staphylococcus aureus subsp. aureus ATCC® 33591™ and Candida albicans ATCC® 24433™. Finally, cytotoxicity tests of 50 selected library extracts and isolated compounds were done against two cell lines namely MCF-7 (breast cancer) and HEK-293 (kidney embryonic).
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Chauvin-Hameau, Corentin Guy Claude. "Informative path planning for algae farm surveying." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-276249.
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Algae farms need to be regularly monitored to control growth rate or check for signs of diseases. As marine farms are setup farther from the coasts, the need for developing robots capable of carrying out these tasks autonomously increases. This thesis investigates trajectory generation for an underwater robot monitoring an algae farm. It encompasses a Kalman Filter used to update a Gaussian Process, used to store information about the algae, Informative Path Planning to generate trajectories which maximise information gain during the survey, and a Linear Time Varying Model Predictive Controller capable of tracking complex three dimensional paths. A simulation of the farm, the robot and its sensors is used to validate the efficiency of the proposed method.Algodlingar ligger under vattnet, och behöver övervakas ofta, för att till exempel kontrollera tillväxthastigheten hos algerna eller söka efter tecken på sjukdom. Eftersom algodlingar ofta ligger långt ifrån kusten behöver man utveckla robotar som kan fullgöra dessa uppgifter autonomt. Denna masteruppsats handlar om ruttplanering för en robot som undersöker sådana algodlingar. Den föreslagna metoden använder ett Kalman - filter för att uppdatera en Gaussisk process som beskriver känd information om algodlingen. Ruttplaneringen genomförs sedan för att maximera informationvinsten över en given planeringshorisont. Vi beskriver även en modell-prediktiv regulator som följer de komplexa tredimensionella rutter som planeras. Slutligen används en simulering av roboten, dess sensorer, och algodlingen för att utvärdera den föreslagna metoden.
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Sjöhag, Elin. "Algae hydrocarbons designed for bio-based lubricants." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279335.
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Smörjmedel är en nödvändighet för maskiner för att minska slitage och energiförbrukning. Dock är över 95% av de använda smörjmedlen i dag fossilbaserade. Smörjmedel baserade på vegetabiliska oljor finns tillgängliga men har ofta en lägre oxidativ stabilitet och sämre lågtemperaturegenskaper än deras fossilbaserade motsvarigheter. Ett annat hinder att övervinna är att ersätta vanligt använda förtjockningsmedel i halvfast smörjmedel med biobaserat alternativ vilket också visat sig vara en utmanande uppgift. Representanter för marina biomassa som mikro- och makroalger har potential att användas i framtiden som förnybar råvara källor på grund av deras kemiska sammansättningar såväl som gynnsamma odlingsförhållanden. Mikroalger har ett högt lipidinnehåll och vissa arter har ett högt innehåll av kolväten som liknar råolja. Makroalger har ett högt innehåll av polysackarider med en förtjockningsförmåga i vatten. Även om mikroalger innehåller lovande kolväten och lipider som kan användas i smörjmedelsapplikationer är det idag inte ekonomiskt möjligt att använda mikroalger för att producera produkter med lågt värde. Även makroalger är för kostsamma att kultivera för billiga produkter, För att kunna använda polysackarider som tillsatser i olja måste de vara mer hydrofoba. I denna studie oxiderades alginat först i en ringöppningsreaktion, för att senare reduceras i en Schiff-basformation och reduktion till en mer amfifil polysackarid. Resultaten visade en hög nedbrytning av polysackariden både i oxidationsreaktionen och i reduktionsreaktionen, från en startmolekylvikt av 580 000 g/mol till ~ 10 000 g/mol. Etanol kunde användas i oxidationsreaktionen för att öka den möjliga alginatkoncentrationen. Både FTIR- och 1H-NMR-resultaten indikerade en lyckad oxidation och reduktion. Framtida arbete involverar inblandning av det hydrofobt modifierade alginatet i en basolja och utvärdering av effekten av den erhållna biobaserade basoljekomponenten på oljeegenskaperna, till exempelökning av viskositeten, oxidationsstabilitet och förtjockningsbeteenden.Lubricants are a necessity for machineries in order to reduce friction and wear. However, over 95% of the lubricants used today are fossil-based. Vegetable oil-based lubricants are available but often possess lower oxidative stability and poorer low temperature properties than their fossil-based counterparts. Vegetable oils are therefore not a perfect solution to reduce crude oil usage. Another obstacle to overcome would be a replacement of commonly used thickeners in semisolid lubricants with bio-based alternative, which has proven to be a challenging task. Marine biomass representatives such as micro-and macroalgae have the potential to be used in the future as renewable feedstock sources due to their chemical compositions as well as beneficial cultivation conditions such as usage of non-arable land and saltwater. Microalgae have a high lipid content, and in some species a high content of hydrocarbons similar to crude oil. Macroalgae have a high content of polysaccharides, some with gelling abilities. Even though microalgae contain promising hydrocarbons and lipids that can be used in lubricant applications, it is currently not economically feasible to use microalgae to produce low valueproducts. Macroalgae are also too expensive to cultivate to be used in low price products. In order to use polysaccharides as additives in oil, they need to be more amphiphilic. In this study, alginate, derived from brown seaweed, was first oxidized in a ring opening reaction to later be reduced in a Schiff base formation and reduction to introduce more hydrophobic side groups. The results revealed a severe degradation of the polysaccharide both in the oxidation and in the reduction reaction, from a starting molecular weight of 580 000 g/mol to ~ 10 000 g/mol. Ethanol was proved to be a suitable solvent in the oxidation reaction which increased the possible alginate concentration. Both FTIR and 1H-NMR results indicated a successful oxidation and reduction. Future work involves incorporation of the hydrophobically modified alginate in a base oil and evaluation of the presence of the obtained bio-based base oil component on the oil properties, for example viscosity increase, oxidation stability and thickening behaviors.
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Balch, Brian Palmer. "Industrial Transesterification of Cultivated Algae for Biofuel." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/612548.
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The objective of our design was to create a chemical plant that uses cultivated algae grown on site in order to produce a biofuel as an alternative energy source. Currently there is a push for sustainable energy sources and biologically produced fuels are attractive due to their near net-zero carbon emissions. Algae provides a valuable source of energy due to its growth rate and sustainability. Chemical engineering principles were utilized in design; a supercritical carbon dioxide extractor for the triglycerides in the algae cells, base catalyzed transesterification reaction in continuously stirred reactors in series and separation processes at the end in order to produce a high grade biofuel for consumer applications. Emphasis on environmental consideration also went into the design, such as the use of carbon dioxide for both the growth of the algae and solid extraction process and methanol used for the transesterification and liquid extraction, allowing for easy recycle and further reducing the environmental footprint the product fuel will have.
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LaRue, Kate, Brian Balch, Chris Jabczynski, and Connor Swensen. "INDUSTRIAL TRANSESTERIFICATION OF CULTIVATED ALGAE FOR BIOFUEL." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/613238.
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Stevens, Kim. "Multiplicity of viral infection in brown algae." Thesis, University of Plymouth, 2014. http://hdl.handle.net/10026.1/3156.
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Brown algae are important primary producers and habitat formers in coastal environments and are believed to have evolved multicellularity independently of the other eukaryotes. The phaeoviruses that infect them form a stable lysogenic relationship with their host via genome integration, but have only been extensively studied in two genera: Ectocarpus and Feldmannia. In this study I aim to improve our understanding of the genetic diversity, host range and distribution of phaeoviruses. Sequencing and phylogenetic analysis of amplified fragments of three core phaeoviral genes (encoding major capsid protein (MCP), DNA polymerase and superfamily III helicase) of phaeovirus infected algae confirmed the suspected phaeoviral identity of viruses infecting E. fasciculatus, F. simplex, Pilayella littoralis, Myriotrichia clavaeformis and Hincksia hincksiae. Furthermore, this approach revealed multiple virus sequence variants within individual strains, and moreover that the variants formed two distinct subgroups. Subgroup A was highly conserved and observed in multiple algal genera, whereas subgroup B was much more diverse, but only found in Feldmannia species. Transcriptome sequencing of an actively infected F. irregularis strain revealed polymorphisms within key viral genes, suggesting that multiple variants were indeed active within this strain. High resolution melt curve (HRM) technology was used to develop a high throughput screening method for detecting phaeoviral MCP as a proxy for detection of phaeoviruses. This technique was also able to assign 88% of those detected to one of the subgroups, based on their differing melting temperature distributions. This was then applied to 1034 Ectocarpus isolates collected from around Europe and South America, and in accordance with previous studies of phaeoviral infection, 43-79% of strains contain virus sequence (depending on species). 17% of the isolates tested even contained sequence from both subgroups. 82 Laminariales strains, close relatives of the Ectocarpales, were also screened because they comprise commercially important kelp species but are not known to be infected by viruses. 10-17% of these tested positive for phaeoviral MCP, which when sequenced formed a separate group within the phaeoviruses. This finding could have a major impact on the kelp farming industry if the viruses are found to affect reproduction as happens in the Ectocarpales. The discovery of two subgroups is contrary to current beliefs that the phaeoviruses are a single monophyletic group, and that each species of alga has its own phaeovirus, casting doubt on the usefulness of the current convention of naming each phaeovirus after its host. It appears that the subgroup B viruses have begun to evolve away from the stable, K-selected subgroup A viruses towards a more r- type strategy with higher mutation and diversification. This study has identified potential mechanisms that may influence this shift, including mutations in a region of the DNA polymerase known to negatively affect DNA replication fidelity, combined with an active integrase and lack of a proofreading exonuclease, along with the observed infection of individuals with both phaeovirusal subgroups. The resulting mutations and recombinations could lead to the diversity observed here, and may provide a suitable model for the study of other emergent virus infections.
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Tam, Carol Elizabeth. "A morphological and cytological study of Audouinella porphyrae and A. vaga (Rhodophyta)." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25055.
Full textAbstract:
A comparative study was made between two similar red algal endophytes, Audouinella porphyrae (Drew) Garbary and Audouinella vaga (Drew) Garbary, Hansen et Scagel, (Acrochaetiaceae, Acrochaetiales) and their red algal hosts Porphyra spp. and Pterosiphonia bipinnata, respectively. Both endophytes have axial, stellate chloroplasts with a central pyrenoid and reside in their host's cell walls, producing erect portions outside the host that may bear monosporangia. The endophytes were cultured "free" from their hosts and morphological and cytological features of the free-living forms were compared with field material. Although the two endophytes differ significantly in cell dimensions and branching patterns, the free-living forms do not retain these differences. Cell dimensions, branching patterns and developmental patterns are identical in the two free-living forms. Asexual reproduction with regeneration by monospores was observed. Sexual reproduction was not observed in either endophytic or free-living forms of the endophytes. Free-living forms were used for re-infection and cross-infection experiments. Under all experimental conditions, the endophytes showed only epiphytic growth. The hosts seem to have some effect on both of the endophytes. Epiphytes, Audouinella porphyrae and A. vaga were not selective and grew on both hosts, Porphyra torta and Pterosiphonia bipinnata. Both epiphtyes growing on blades of Porphyra tended to branch and have more extensive prostrate portions (3-5 cells) whereas both epiphytes on Pterosiphoni a bipinnata tend not to branch and have only 1-2 cells in the prostrate portions. Ultrastructural studies of both endophytes showed typical florideophycean features. Ultrastructural features of field material of the two endophytes were similar and free-living, cultured endophytes were similar to field material. A large vacuole was observed in sections of the field material of both prostrate and erect portions whereas this was not observed in cultured material. Based on the results of this study it is proposed that the two endophytes are conspecific. Audouinella vaga is referred to synonymy in Audouinella porphyrae (Drew) Garbary, Hansen et Scagel.Science, Faculty of
Botany, Department of
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Murúa, Pedro. "Molecular and cell biology of novel brown algal pathosystems." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=238693.
Full textAbstract:
Algae are increasingly being used in human affairs. Alongside with higher volumes, threats for seaweed natural reservoirs and seaweed farming are starting to appear. Epidemics seems a key complication, similar to agriculture and animal aquaculture. However, phycopathologies are much more under documented, and future diseases are currently difficult to foresee. Thus, efforts should be stressed on biodiversity of algal pathogens and algal defense strategies against diseases. This thesis is divided in two parts: the first section comprises Chapters Two and Three, which describe novel algal pathosystems from cell biology and molecular phylogeny perspectives. Chapter Two characterizes the obligate parasite Maullinia braseltonii sp. nov., a phytomyxid infecting Durvillaea (bull kelp) in the Southern hemisphere. Chapter Three reports new records, cell plasticity and epidemiology of the endophyte Laminariocolax aecidioides infecting Lessonia berteroana (huiro negro) in northern Chile. The two hosts aforementioned have commercial importance, and remarkable roles in coastal ecology in temperate marine habitats in the Southern hemisphere. Chapters Four, Five and Six correspond to a second section and describe cellular processes in novel brown algal pathosystems, related with infection and immunity responses. In Chapter Four, using the Macrocystis/Anisolpidium as a model, microscopy evidence indicate that autophagy is a key cellular process used either to help starving pathogen syncytia to survive (controlled) or to kill themselves (abortive), probably induced by the host. Likewise, host autophagy was also widely observed and may be involved in the neutralization of early-stage oomycetes or nutrient recycling to mount defences. Chapter Five shows the results on a screening of ca. 40 strains from different brown algal orders, to phenotype cellular defense markers against two phylogenetic distant pathogens (Anisolpidium ectocarpii and Maullinia ectocarpii). Overall, responses such as cell wall re-arrangements, programmed cell death, autophagy and ROS accumulation were confirmed to be at least partially conserved across different Phaeophycean lineages. Chapter 6 reports a boost on the phlorotannin metabolism in the model brown alga Ectocarpus (e.g. physode formation and polyketide synthase gene expression) after pathogen challenging, suggesting a similar protective role of this molecule as against grazers and deleterious light regimes. Phlorotannins role however needs to be elucidated.