Dissertations / Theses: 'Polysaccharides marins'

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Lelchat, Florian. "Enzymes de dépolymérisation d'exopolysaccharides bactériens marins." Thesis, Brest, 2014. http://www.theses.fr/2014BRES0070/document.

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Les exopolysaccharides (EPS) sont des biopolymères pouvant être synthétisés par les Eucaryotes, lesArchées et les Procaryotes. Au niveau bactérien les EPS peuvent être impliqués dans la constitution du biofilm (phénomène de biofouling) lors de la colonisation de nouveaux milieux. Ces biopolymères ont des propriétés physico-chimiques et biologiques spécifiques et innovantes à haut potentiel biotechnologique (agroalimentaire, santé, cosmétique, ingénierie environnementale ...). A l'opposé, leurs rôles écologiques lors de l'établissement de biofilms de souches potentiellement pathogènes peuvent rendre leur éradication compliquée.Les processus de dépolymérisation par voie enzymatique sont nécessaires pour réaliser l'élucidation structurale fine des EPS complexes, pour la production de dérivés bio-actifs calibrés à faible poids moléculaire ou pour empêcher la formation de biofilm. La mise en évidence de ces phénomènes enzymatiques sur des microorganismes modèles peut également permettre de mieux cerner les flux de matière au sein de certains compartiments biologiques en particulier en milieu marin. Néanmoins la complexité et grande diversité de structures des EPS rendent la recherche d’enzymes de dépolymérisation spécifiques difficile.Deux stratégies ont été employées pour trouver des sources d'enzymes.1. La voie bactérienne via l’utilisation de bactéries marines productrices d’EPS.2. La voie virale par la recherche de polysaccharidases de bactériophages marins. En plus d’EPS marins déjà connus, de nouveaux substrats (EPS) originaux ont été produits et caractérisés à partir de batéries marines d’intérêts biotechnologiques et/ou écologiques pour les besoins du projet. Un criblage enzymatique sur 11 souches bactériennes du genre Alteromonas a permis de mettre en évidence que 7 d’entre elles présentaient une activité de dépolymérisation endogène vis-à-vis de leur propre EPS. Une bioprospection a été réalisée afin de constituer une virothèque à partir d’hôtes bactériens producteurs d’EPS dans le but de fournir une source de Cazymes virales potentielles. Sur 33 bactériophages, 10 ont été sélectionnés pour leur capacité à rester infectieux lorsque leurs hôtes synthétisent des EPS. Finalement un système hôte/virus a été sélectionné.Les 5 virus (appelés Carin-1 à 5) infectant Cobetia marina DSMZ 4741 ont été étudiés au niveau de leurs traits de vie. Les capacités de dépolymérisation de Carin-1 et Carin-5 sur l'EPS L6 ont été explorés plus en détail. En parallèle, la structure chimique de l'EPS L6 a été intégralement élucidée
Exopolysaccharides (EPSs) are a class of biopolymer synthesized by Eukarya, Archea and Procarya.Bacterial EPSs are involved in biofilm establishment and biofouling phenomenon. These polymers have physicochemical and biological properties suitable with biotechnological valorization. At the opposite, their involvment in biofouling of pathogenic strains can be problematic.Enzymatic depolymerization process are necessary for EPSs structural elucidation, Bioactive oligosaccharides production or to disrupt polysaccharidic biofilms. The highlight of enzymatic phenomenon can help to understand biogeochimical process in the ocean. Nevertheless the important structural diversity as well as their complexity make the sourcing of specific enzymes difficult.Two strategies were used to find enzymes.1. The bacterial way by using EPS-producing marine strains2. The viral way, with marine bacteriophages.For the need of the study, several EPS-substrates were produced and characterized. The majority of them were totally new. An enzymatic screening on 11 marine Alteromonas strains shown that 6 were able to depolymerize their EPS in an endogenous way. A bioprospection was realized to isolates marine bacteriophages with potential viral Cazymes. 10 out of 33 phages were selectionned for their ability to be infectious with their hosts in EPS production induced. Finally, a host/virus system was chosen. The bacteriophages infecting Cobetia marina DSMZ 4741 (named Carin-1 to 5) were studied. The polysaccharidase activities of Carin-1 and Carin-5 on the L6 EPS were studied more deeply. In parallel, the complete structural elucidation of the L6 EPS was realized

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Tsotetzo, Honore. "Valorisation des polysaccharides marins : élaboration de nanocomposites et synthèse de graphène dopé." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC216/document.

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La chimie se doit de développer de nouveaux axes de recherche à la fois respectueux de la nature et s’inscrivant dans une démarche globale éco-compatible. Dans ce contexte, l’utilisation des polymères naturels, notamment les polysaccharides, permet de synthétiser des matériaux innovants des applications dans de nombreux secteurs industriels. L’objectif de ce travail est de valoriser les polysaccharides marins tels que le chitosane et le κ-carraghénane à travers l’exploration de deux axes de recherches. Le premier axe est consacré à l’amélioration des propriétés mécaniques, électriques et de sorption de biopolymères par l’incorporation de graphène. Un protocole original a permis de disperser très efficacement du graphène au sein du chitosane pour la conception de films et d’aérogels nanocomposites. L’analyse des films a mis en évidence une amélioration simultanée de la rigidité, de la résistance, et de l’élongation à rupture, pour de faibles teneurs en graphène. Le seuil de percolation permettant l’obtention d’une conductivité électrique n’a pas été atteint aux faibles taux de charges utilisés. L’étude des aérogels chitosane/graphène a, quant à elle, révélé que l’incorporation de graphène aux aérogels de chitosane permettait d’augmenter leur capacité d’adsorption de colorants.Le deuxième axe concerne l’introduction d’hétéroatomes dans la structure carbonée du graphène. Pour obtenir du graphène dopé en azote et en soufre, des aérogels de polysaccharides marins ont été synthétisés, puis pyrolysés dans des conditions contrôlées. Les aérogels carbonés obtenus sont ensuite exfoliés dans l’eau par l’utilisation d’ultrasons. Les groupements amine du chitosane ont permis d’obtenir avec un haut rendement un graphène dopé avec un taux de 5 % d’azote. De plus, il a été possible de moduler de 5 % à 11 %ce taux d’azote par l’emploi de liquide ionique tel que le [EMIm][dca]. De façon similaire, les groupements sulfate du κ-carraghénane ont permis de doper du graphène en soufre avec un taux d’atomes de soufre de 1,5 %
The chemistry have to develop new research axis both respectful of the nature and joining an eco-compatible global approach. In this context, use natural polysaccharides allow to synthesize innovative materials for applications in many industries fields. The aim of this work is add value to the marine polysaccharide such as chitosan and κ-carrageenan through two research axis.The first axis is consecrated to increase the mechanical, electrical and color sorption properties by introduce graphene filler in biopolymer matrice. An easy and original protocol allowed scattering very effectively graphene in chitosan to design films and aerogels nanocomposites. The analyse of nanocomposite films show an improvement of stiffness, tensile strength and elongation break at the same time with low content of graphene. However, the percolation threshold was not reach to bring electrics properties in films. The study of chitosan/graphene aerogel reveals that graphene allows an increase of color agent adsorbing power such as eosin Y compared with aerogels chitosan.The second axis concerns the introduction of heteroatom in graphene carbon structure. To obtain nitrogen-doped graphene and sulphur-doped graphene, it requires the synthesis of marine polysaccharide aerogel, and their pyrolysis under controlled conditions. The carbon aerogels are exfoliated in water with sonification. Amine groups in chitosan allowed through this process a nitrogen-doped graphene with high yield and nitrogen rate of 5 %. Moreover, it was possible to modulate nitrogen rate with ionic liquid such as [EMIm][dca]. So the nitrogen atom rate increases from 5% to 11%. In similar way, sulfate group in κ-carrageenan gives sulphur-doped graphene with sulphur rate of 1,5%

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Jouannin, Claire. "Apport des polysaccharides marins pour la catalyse en phase liquide ionique supportée." Caen, 2012. http://www.theses.fr/2012CAEN2035.

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L’objectif de cette thèse est d’évaluer l’apport des polysaccharides marins pour la catalyse en phase liquide ionique supportée. Les alginates et le chitosane sont les deux polysaccharides à partir desquels des supports de porosité et de fonctionnalités variées ont été préparés. Deux méthodes d’immobilisation de liquide ionique sur les supports biopolymères ont été utilisées : par adsorption et par confinement. Les catalyseurs en phase liquide ionique supportée sur biopolymère (biopolymère-SILCs) ont été élaborés sous des mises en forme variées de billes, mousses cylindriques et disques, pour des applications en systèmes de type batch ainsi qu’en flux continu. Les propriétés texturales, les charges en liquide ionique et en complexe organométallique ainsi que la stabilité des biopolymère-SILCs ont été déterminées; et les espèces catalytiques actives identifiées. Les performances et les limitations des biopolymère-SILCs ont ensuite été évaluées dans deux réactions modèles pallado-catalysées : la substitution allylique de Tsuji-Trost et l’hydrogénation de composés nitrés aromatiques, cette dernière réaction ayant été réalisée en milieu aqueux. Ces études mettent en évidence l’influence des paramètres d’élaboration des biopolymère-SILCs sur leur structure et sur leur activité catalytique
The objective of this thesis is to evaluate the contribution of marine polysaccharides to the supported ionic liquid catalysis. Alginates and chitosan are the two polysaccharides used to prepare supports with different porosity and functionality. The immobilization of the ionic liquid phase onto the biopolymer supports was performed by two ways: by adsorption and by confinement. Biopolymer supported ionic liquid catalysts (biopolymer-SILCs) were prepared in the form of beads, cylindrical scaffolds and discs, for applications in batch systems as well as in continuous flow. The textural properties, the stability, the ionic liquid and catalyst loadings of the biopolymer-SILCs were determined and the catalytic species identified. The performance and limitations of the biopolymer-SILCs were then evaluated in two model pallado-catalyzed reactions: the allylic substitution of Tsuji-Trost and the hydrogenation of aromatic nitro compounds, this last reaction being performed in aqueous medium. These studies highlight the influence of processing parameters of biopolymer-SILCs on their structure and on their catalytic activity

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Jabeen, Mehwish. "Anti-viral activity of marine polysaccharides against respiratory viruses." Thesis, Lyon, 2021. http://www.theses.fr/2021LYSE1325.

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Les infections respiratoires virales sont une des principales causes de morbidité et de mortalité dans le monde. Les infections virales du tractus respiratoire (vRTIs) sont dues à différentes familles de virus telles que les picornavirus, les coronavirus (CoV), les ortho- and paramyxovirus, les adénovirus et les herpesvirus. Les vRTIs comptent parmi les maladies les plus fréquentes dans le système de soin médical. Bien que la plupart des symptômes associés à ces virus se résolvent spontanément et ne sont pas létaux, dans certains cas, ils peuvent être associés à des complications menaçant le pronostic vital qui nécessite une hospitalisation et induit de lourdes charges économiques et sociales. Malgré des avancements majeurs dans le domaine de la virologie, il n’existe toujours pas de traitement spécifique ciblé pour la plupart des infections respiratoires virales. Les traitements symptomatiques ou antiviraux restent les outils majeurs contre les vRTIs car il n’existe pas de vaccins efficaces disponible contre la plupart des virus respiratoires, sauf contre la grippe, l’adénovirus et plus récemment contre le SARS-CoV-2. Cependant, le prix et la rapidité de disponibilité de ces vaccins selon la saisonnalité est globalement questionnable. Les traitements approuvés contre les virus respiratoires reposent exclusivement sur des médicaments synthétiques qui ont de potentiels effets secondaires et entraînent l’émergence de résistances virales. Dû au manque de traitement spécifique et de vaccins efficaces, la découverte d’alternatives naturelles, telle que les polysaccharides marins, est indispensable. Les polysaccharides marins sont reconnus dans la littérature scientifique pour leurs nombreuses propriétés antivirales, anti oxydantes, anti tumorales ou immunomodulatrices par exemple. Fait intéressant, les polysaccharides sulfatés (SPS) ont montré des activités antivirales significatives contre différent virus. Leur potentiel antiviral varié est attribué à leur diversité de structures. En dépit de la grande diversité d’algues marines existantes, les SPS ont un mécanisme d’action plutôt similaires basé sur leurs régions anioniques. Ainsi, ils exercent leur propriétés virucides en prévenant l’infection virale. Cependant, cette activité est très dépendante des caractéristiques structurales des SPS qui peuvent également agir à d’autres étapes du cycle viral. Récemment, plusieurs SPS ont montré des activités antivirales prometteuses contre le SARS-CoV-2. Parmi les SPS issus d’algues marines, le fucoidan et le carraghénane sont les polysaccharides à visée antivirale les plus étudiés dû à leur efficacité antivirale à large spectre. L’objectif de ces travaux de these a été d’évaluer l’efficacité antivirale de polysaccharides d’origine marine contre des virus respiratoires. Pour cela, l’activité antivirale de fucoidans de différentes sources ont été évaluées in vitro contre le HRV, le virus de la grippe et le SARS-CoV-2. L’efficacité d’inhibition virale a été quantifiée par TCID50 (50 % Tissue Culture Infectious Dose) et la détermination du mécanisme d’action a été réalisée par modulation de la séquence d’ajout des fucoidans dans le processus d’infection (time of addition assays). Les activités antivirales des polysaccharides testés ont été comparées à des contrôles naturels (Carragelose) et synthétiques (pleconaril, ribavirin). Aucune activité antivirale n’a été mise en évidence contre le HRV (virus non-enveloppé), alors qu’une activité antivirale modérée à forte a été quantifiée contre le virus de la grippe et le SARS-CoV-2 (virus enveloppés). Ces résultats pourraient mettre en avant une plus grande affinité des SPS marins pour les virus enveloppés. De plus, Une activité antivirale plus élevée a été montrée dans les cas des polysaccharides les plus purs, indiquant l’importance du processus de purification et de caractérisation des extraits naturels avant de pouvoir les considérer comme candidats antiviraux d’origine naturelle
Respiratory viral infections are one of the leading causes of morbidilty and mortality worldwide. Viral respiratory tract infections (vRTIs) can be due to several families of viruses such as picornaviruses, coronaviruses (CoV), ortho- and paramyxoviruses, adenoviruses and herpesviruses. vRTIs are among the most common diseases in medical health care. Although most of the symptoms associated with these viruses are self-resolving and non-fatal, they have a huge impact on the quality of life and productivity. In certain cases, they are associated with various life threatening complications that consequently result in hospitalization and associated financial and social burden. Despite massive advancements in virology field, no specific treatment exists for most respiratory viral infections. Symptomatic therapies or anti-viral medications are still the major tools to treat vRTIs as vaccines are currently not yet available for most of the respiratory viruses except against influenza (limited efficacy), adenovirus (restricted use) and more recently, against SARS-CoV-2. However, cost effective production and timely availablity of these vaccines globally is still questionable. Approved therapies against respiratory viruses rely almost exclusively on synthetic drugs that have potential side effects, restricting their use. Besides, these anti-viral agents lack targeted therapeutic activity towards respiratory viruses. and trigger the emergence of viral resistance, that is a major public health problem. Due to the lack of optimal medication and effective vaccines, the search for alternative natural therapies, such as sulfated marine polysaccharides, is indispensable. Marine polysaccharides are very well known in the litrature for their numerous benefits including anti-viral, antioxidant, antitumor, immunomodulatory, vaccine preparation, cell/ gene therapy, drug delivery to biomaterial synthesis. Interestingly, sulphated polysaccharides (SPS) have shown significant anti-viral activities against different viruses. Their distinctive anti-viral potential is attributed to their diverse structure. Despite the large diveristy of marine algae, the SPS mainly act through a similar mechanism: the anionic regions of polysaccharides interact with viral glycoproteins to prevent their attachment to cell membranes. Therefore, they exert virustatic properties by preventing viral infection. However, this activity is dependant on the structural features of SPS which could accordingly act at different stages of viral cycle. Recently, various SPS have shown promising activity agaisnt SARS-CoV-2 and are in further assessment for their use as natural anti-virals. Among the SPS from marine algae, mainly fucoidan and carrageenan have gained huge importance as anti-virals due to their broad spectrum anti-viral efficacy. The objective of this thesis was to evaluate the anti-viral efficacy of marine polysaccharides against respiratory viruses. For this purpose, the anti-viral activity of fucoidan from different sources was assessed against HRV, IV as well as SARS-CoV-2 through in-vitro assays. The viral inhibition efficacy was assessed mainly by Tissue Culture Infectious Dose (TCID50) inhibition assay and the mechanism of inhibition was determined through time of addition assays (TOA). The anti-viral activity of tested polysaccharides was compared with natural (Carragelose) and synthetic anti-virals (pleconaril, ribavarin). No anti-viral activity was seen in case of HRV (non-enveloped virus) whereas, important anti-viral activity was seen against IV and SARS-CoV-2 (enveloped viruses). These results probably highlighted the greater sensitivity of polyanionic marine polysaccharides towards the enveloped viruses. Furthermore, better anti-viral activity was seen in case of pure polysaccharide, highlighting the importance of marine extract purification and characterization before considering their use as drug of natural origin

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Mocaër, Pierre-Yves. "From gene to ecosystem : an integrative study of polysaccharide depolymerases bound to marine viruses." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS553.

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Les virus constituent une force motrice pour le fonctionnement des écosystèmes marins. En tuant leur hôte par lyse cellulaire, ils influencent la diversité microbienne et les cycles biogéochimiques globaux. Dans cette étude, je me suis intéressé à l’implication des polysaccharide dépolymérases (ou EPS dépolymérases) associées aux virus de bactéries (phages) dans la régulation des activités virales et leurs conséquences sur la biogéochimie océanique. Ces enzymes confèrent aux phages la faculté de dégrader les exopolysaccharides (EPS) excrétés par leurs hôtes avant d’atteindre leurs récepteurs membranaires. Nous avons étudié de façon intégrative, du gène à l’écosystème, les EPS dépolymérases associées à 2 phages modèles (Podoviridae). Une combinaison d’approches a révélé que les gènes codant pour ces activités sont génétiquement éloignés des séquences connues. Une étude approfondie de l’une de ces enzymes (Dpo31, associée au phage de Cobetia marina) suggère son appartenance aux glycoside hydrolases et révèle une architecture moléculaire nouvelle. De plus, une expérience en microcosme a montré que les dépolymérases virales réduisent la biodisponibilité des EPS et participent à la production de matière réfractaire dans le milieu naturel. Compte tenu de la prédominance des virus dans l’océan, ce processus jusqu'ici négligé pourrait avoir des implications biogéochimiques importantes
Viruses represent a driving force for the functioning and evolution of marine ecosystems. Through the lysis of their hosts, viruses profoundly influence the diversity and biogeochemistry of the ocean. In this study, I investigated the implications of polysaccharide depolymerases (or EPS depolymerases) associated to bacterial viruses (phages) in the regulation of viral activities and their consequences on ocean biogeochemistry. They confer to phages the ability to degrade the exopolysaccharides (EPS) excreted by their hosts in order to access their membrane receptors. Here, we studied integratively, from gene to ecosystem, the EPS depolymerases associated to 2 model phages (Podoviridae). A combination of approaches revealed that the genes encoding these activities are genetically distant from known sequences. An in-depth study showed that the enzyme Dpo31 (associated to Cobetia marina phage) is a glycoside hydrolases and revealed a novel molecular architecture. In the ocean, bacterial EPS constitute a significant pool of dissolved organic carbon. A microcosm experiment showed that viral depolymerases reduce the bioavailability of EPS and contribute to the production of refractory matter in the natural environment. Considering the predominance of viruses in the sea, this, so far, neglected process could have important implications for the functioning of the ocean

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Petersen, Kirsten [Verfasser]. "Emulsionsstabilisierung durch marine Polysaccharide / Kirsten Petersen." Kiel : Universitätsbibliothek Kiel, 2013. http://d-nb.info/1045604062/34.

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Labourel, Aurore. "Etudes structurales et fonctionnelles d’enzymes du métabolisme de la laminarine de deux organismes modèles émergeants, l’algue brune Ectocarpus siliculosus et la bactérie marine Zobellia galactanivorans." Paris 6, 2013. http://www.theses.fr/2013PA066728.

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La laminarine est le polysaccharide de stockage des algues brunes. Récemment, Ectocarpus siliculosus a été développée comme modèle génétique et génomique des algues brunes. L’analyse de son génome a mis en évidence des gènes candidats impliqués dans le métabolisme central de la laminarine. Afin de réaliser des études fonctionnelles, une stratégie de clonage en moyen débit a été appliquée sur ces différents gènes. Les algues brunes étant une biomasse importante, la laminarine est une source de carbone considérable pour les bactéries marines hétérotrophes. La bactérie marine Zobellia galactanivorans devient actuellement un modèle pour la bioconversion des polysaccharides d’algues. L’annotation de son génome a révélé la présence de 5 laminarinases putatives présentant des architectures modulaires variées. L‘expression hétérologue et la purification des modules catalytiques ZgLamAGH16, ZgLamCGH16, ainsi que celle du CBM6 associé à ZgLamCGH16, ont permis leur caractérisation biochimique. Des mutants inactifs des modules catalytiques ont été obtenus par mutagénèse dirigée, permettant l’obtention de complexes enzymes-substrats. C’est ainsi que la structure 3D de ZgLamAGH16 contient des oligosaccharides de substrats naturels tandis que celle de ZglamCGH16 a été obtenue en complexe avec un thio-hexasaccharide de β-1,3-glucane. L’obtention de la structure de ZgLamCCBM6 associée à des expériences de microcalorimétrie suggère que ce CBM6 peut fixer la laminarine dans ses deux sites de fixation simultanément. L’ensemble de ces résultats sont discutés et intégrés dans un contexte biologique et évolutif
Laminarin is a storage polysaccharide found in brown algae. Ectocarpus siliculosus has been recently established as a genetic and genomic model for brown algae. The analysis of its genome sequence revealed some candidate genes involved in the central metabolism of laminarin. In order to go onto functional studies, I have applied a medium throughput cloning strategy on these genes. Brown algae being an important coastal biomass, laminarin is also a significant carbon source for marine heterotrophic bacteria. The marine bacterium Zobellia galactanivorans is currently being established as a model bacterium for the bioconversion of algal polysaccharides. Its genome sequence encodes 5 putative laminarinases displaying various modular architectures. The heterologous expression and the purification of the catalytic modules ZgLamAGH16, ZgLamCGH16 and those of the carbohydrate-binding module CBM6 appended to ZgLamCCBM6, have enabled their biochemical characterization. Inactive mutants of the catalytic modules were obtained by site directed mutagenesis. They were used to generate enzyme-substrate complexes. The 3D-structure of ZgLamAGH16 was solved by X-ray crystallography, and oligoglucans of natural substrates were present in the catalytic site. ZgLamCGH16 was obtained in complex with a thio-hexasaccharide of β-1,3-glucan. The ZgLamCCBM6 structure associated with microcalorimetry experiments suggests that this CBM6 can bind laminarin simultaneously in its two binding clefts. The whole results are discussed and integrated in a biologic and evolutive context

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January, Grant Garren. "Bioprospecting for bioactive polysaccharides from marine algae endemic to South Africa." University of the Western Cape, 2016. http://hdl.handle.net/11394/5322.

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>Magister Scientiae - MSc
Fucoidan is a marine-derived sulphated polysaccharide with bioactive properties ideal for the food, chemical and pharmaceutical industries. The polysaccharide consists largely of L-fucose, has a highly heterogeneous structure and is of diverse origin. Fucoidan was extracted from Ecklonia maxima, Laminaria pallida and Splachnidium rugosum and the effect of different extraction methods on fucoidan heterogeneity was assessed. Extraction methods employed hot water, hydrochloric acid or calcium chloride salt. Fucoidan yield and purity were determined by various colorimetric assays. Highest fucoidan yield was obtained with the hot water extraction method as seen by highest L-fucose content. Splachnidium rugosum extracts contained ~5 times more L-fucose than Ecklonia maxima and Laminaria pallida extracts. The salt extraction method yielded extracts free of contaminants, however L-fucose content in all extracts was >20 times lower. Acid extraction yielded highest levels of uronic acid contamination and liberated sulphate from the fucoidan polysaccharide. The fucose-to-sulphate ratio for Ecklonia maxima was approximately 1:5, whilst the ratios for Splachnidium rugosum and Laminaria pallida were approximately 1:1 and 1:2, respectively. The acid and salt extraction methods removed all traces of protein contaminants, while the hot water method retained very low levels of protein. The extraction method used to isolate fucoidan was a determining factor in yield and purity. Chemical compositional analyses of hot water extracts were assessed by gas chromatography mass spectroscopy. Splachnidium rugosum and Laminaria pallida extracts consisted largely of L-fucose, while Ecklonia maxima fucoidan was characterized with high glucose abundance. Crude hot water and acid extracts from Splachnidium rugosum tissue were fractionated and purified by (anionic) ion exchange chromatography as bioactivity has been correlated to lower molecular weight forms. In water extracts, ion exchange chromatography resulted in close to 90% decrease in L-fucose, sulphate and uronic acid, while protein content increased by 57%. Similar results were reported for acid extracts; however protein content did not change significantly. These results show that method of extraction may affect the composition of fucoidan post-purification. Hot water extraction is recommended due to higher fucoidan yield, as reflected by L-fucose content, and higher sulphate-to-fucose ratio. High protein content after ion exchange chromatography was however of concern. Since mucilage in Splachnidium rugosum thallus was free of protein, fucoidan was precipitated from mucilage with ethanol. Fucoidan yield of mucilage was >15-fold higher than content in purified hot water extracts with a sulphate-to-fucose ratio of ~1:1. The average molecular weight of native fucoidan in mucilage was estimated at 2367 kDa. The polysaccharide was hydrolysed by gamma-irradiation levels of 10-50 kGy to fractions ranging between 60 and 15.5 kDa. Hot water crude fucoidan extracts from Ecklonia maxima, Laminaria pallida, and Splachnidium rugosum were assessed for anti-oxidant activity by measuring the ability to scavenge free radicals and the capacity to reduce copper ions with 2,2-Diphenyl-1-picrylhydrazyl and Cupric Reducing Anti-oxidant Capacity assays, respectively. Ecklonia maxima crude fucoidan displayed highest anti-oxidant activity and capacity, having the potential to scavenge reactive oxygen species as well as the capacity to reduce copper to less toxic forms in mammalian systems. Splachnidium rugosum showed weakest anti-oxidant activity and lowest reducing capacity. The anti-cancer activity of crude and purified hot water Splachnidium rugosum extracts, as well as non-irradiated (native) and gamma-irradiated fucoidan, and commercially procured fucoidan were assessed for anti-cancer activity against MCF-7 breast cancer cells. Splachnidium rugosum crude and purified fucoidan displayed a half maximal inhibitory concentration of 0.7 mg/mL and 0.029 mg/mL, respectively. Low cytotoxicity of crude and purified Splachnidium rugosum fucoidan against non-cancerous breast epithelial cell line MCF-12A was observed, as seen by half maximal inhibitory concentration values of 2 mg/mL and 0.663 mg/mL, respectively. The cancer specific selectivity of purified Splachnidium rugosum fucoidan was therefore much higher as reflected by 10-fold higher selectivity index than that of crude fucoidan. Native and low molecular weight gamma-irradiated fucoidan also showed bioactive properties including anti-cancer activity as seen by the reduction of cell proliferation in vitro, whereas crude fucoidan showed the ability to scavenge free radicals, and the capacity to reduce copper ions.
National Research Foundation (NRF)

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Edwards, Jennifer Lynne. "Genes and proteins involved in polysaccharide colonisation by marine microorganisms." Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526977.

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Panagos, Charalampos. "Structural characterisation of marine glycosaminoglycans and their interactions with proteins." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/17864.

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Glycosaminoglycans (GAGs) are a group of structurally related, naturally occurring polysaccharides, found as the carbohydrate moieties of proteoglycans and sometimes as free polysaccharides. GAGs are expressed ubiquitously on animal cell surfaces and within extracellular matrices. All GAGs are sulfated to various degrees, except hyaluronan, which is always non-sulfated. In this project, GAGs and other sulfated carbohydrates were purified from different marine sources and an algae species living in soil, and their structures were characterised, mainly by NMR spectroscopy. Oversulfated dermatan sulfate (DS), fucosylated chondroitin sulfate (fCS) with interesting anti-metastatic properties, a sulfated fucosylated GlcNAc polymer, naturally-occurring cellulose sulfate and a polysaccharide with a repeating disaccharide unit of IdoA-Gal, were some of the more unusual carbohydrates identified. Common GAGs like hyaluronan, chondroitin sulfate A and C, DS and heparin/heparin sulfate-like polysaccharides were also purified from lumpsuckers and ragoworms. Different depolymerisation techniques were also investigated. The effects of Fentontype reaction and photochemical free radical depolymerisation on DS were studied. Elimination of the reducing end IdoA in the case of Fenton-type produced oligosaccharides was established. The oxidisation of reducing end GalNAc to Nacetylgalactosaminic acid, as a result of both depolymerisation techniques, was also identified. In addition, the effect of mild acid hydrolysis on fCS polysaccharides were studied and this technique was deemed unfitting for the depolymerisation of the molecule, as it causes defucosylation and partial desulfation. Finally, human beta-defensin 2 (HBD2) was expressed recombinantly, as a fusion protein with pE-Sumo, in an attempt to design a high yield expression system capable of producing correctly folded protein. The significance of NMR in the identification of the state of the protein and the need for an expression system capable of carrying out correctly the post-translational modifications was demonstrated.

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Hehemann, Jan-Hendrik. "Structural and functional organisation of the agarolytic enzyme system of the marine flavobacterium Zobellia galactanivorans." Paris 6, 2009. http://hal.upmc.fr/tel-01110381v1.

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Zobellia galactanivorans est une Flavobacterie marine capable de dégrader des polysaccharides complexes tels que l’agar qui est largement utilisé en biotechnologie et agroalimentaire. Dans l’écosystème marin les organismes photosynthétiques tels que les algues et les cyanobactéries sont les principaux producteurs de carbone organique. Cette source de carbone est utilisée par les bactéries marines qui sécrètent des glycosides hydrolases afin d’attaquer les algues ou d’hydrolyser la paroi des algues en décomposition. Pour comprendre les mécanismes de recyclage du carbone à partir de ces zones de nutrition préférentielles nous avons décidé d’analyser le système agarolytique de Z. Galactanivorans. Le génome bactérien complet a mis en évidence la présence de neuf agarases de la famille GH 16, confirmant que Z. Galactanivorans possède un système agarolytique complexe pour dégrader cette ressource naturel qu’est l’agar. Sept séquences originales ont été surexprimées grâce à une stratégie de clonage à moyen débit. Une nouvelle ß-agarase (AgaD) a été purifiée à l’homogénéité, puis cristallisée et les données de diffraction ont été collectées à une résolution de 1. 5 Å. La structure a été résolue par remplacement moléculaire et la caractérisation biochimique a été réalisée. De plus, les deux premières ?-porphyranases PorA et PorB ont été identifiées, cristallisées et caractérisées biochimiquement. La diversité d’enzymes agarolytiques reflète les adaptations biologiques dont ont fait preuve certaines bactéries pour s’accommoder à la grande variabilité de l’agarose de la paroi des algues rouges.

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Elboutachfaiti, Redouan. "Procédé d’obtention d’oligosaccharides anioniques (oligouronides et oligosaccharides sulfates) par dégradation enzymatique des polysaccharides d’algues marines." Amiens, 2008. http://www.theses.fr/2008AMIE0124.

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La paroi de l’algue verte Ulva lactuca contient un homopolymère d’acides glucuroniques liés en β-(1®4) non sulfatés : le glucuronane et un deuxième polysaccharide sulfatés de structure complexe nommé ulvane. Dans le but de produire des oligoglucuronanes et des ligoulvanes, un procédé d’extraction du glucuronane et des ulvanes a été mis au point. Dans un deuxième temps, nous avons cherché à produire des oligomères à partir des polysaccharides purifiés. La dégradation radicalaire s’est avérée efficace pour dégrader le polymère d’ulvane en molécules de masse molaire faible, mais elle ne nous a pas permis d’obtenir les oligomères d’ulvane. Nous avons donc recherché des microorganismes exprimant une activité dépolymérisante sur le polysaccharide d’Ulva lactuca. La souche PEC2 a été isolée, elle est proche d’Ochrobactrum triticii, elle exprime une activité glucuronane lyase (GL3) et une activité ulvane lyase (UL2). Les deux enzymes GL3 et UL2 dégradent respectivement les β-(1®4) glucuronanes et les α-(1®4), β-(1®4) rhamnoglucuronane sulfaté. L’utilisation de ces deux nouvelles activités lyase a permis la production d’une quantité importante de b-D-(4,5)-oligoglucuronanes et b-D-(4,5) ligorhamnoglucuronanes sulfatés par clivage du glucuronane et de l’ulvane isolés d’Ulva lactuca. Des oligomères de différents dp ont été purifiées par chromatographie liquide basse pression (exclusion stérique) et caractérisés par RMN 1H et ESI-Q/TOF-MS. Ces oligomères appliqués sur des plants de tomate ont induit l’augmentation d’activités enzymatiques associées aux mécanismes de défense naturelle des plantes contre des pathogènes
In the green algae Ulva lactuca the cell-wall contains two anionic polysaccharides, a homopolymer of glucuronic acid β-(1®4) linked called glucuronan and a sulphated heteropolymer called ulvan. In order to produce pure oligomers from the ulva polysaccharide extracts, a purification process was developed. Low molecular weight molecules were first obtained under a radical degradation, but no oligosaccharides were produced. In order to obtain such oligomers, a strain called PEC2 was selected. The strain closed to the Ochrobactrum triticii species was able to produce a glucuronan lyase (GL3) and an ulvan lyase (UL2). The GL3 extract allows the degradation of β-(1®4) glucuronans and the UL2 extract degrades α-(1®4), β-(1®4) sulfated rhamnoglucuronans. Various b-D-(4,5)-unsaturated oligoglucuronans and sulphated b-D-(4,5)-unsaturated oligorhamnoglucuronans with specific dp were produced and purified using low pressure liquid chromatography (size exclusion). Then they were analyzed by 1H NMR spectroscopy and ESI-Q/TOF-MS. These oligomers applied on tomato plants were shown to induce an increase of enzymatic activities known to be essential against plant pathogens

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Senni, Karim. "Effets de polysaccharides d'origine marine sur le remodelage des tissus gingivaux et dermiques." Paris 13, 2000. http://www.theses.fr/2000PA132031.

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Le remodelage du tissu conjonctif est une phase essentielle à certains phénomènes physiologiques tels que la cicatrisation et les développements embryonnaire et post-natal. Un remodelage matriciel harmonieux nécessite un équilibre finement contrôlé entre synthèses et dégradations macromoléculaires. Toute altération de ces phénomènes conduit à des situations pathologiques ; ainsi une sur-expression des macromolécules matricielles aboutit à diverses fibroses tandis que les pathologies inflammatoires chroniques (parodontites, arthrose, emphysème) impliquent une dérégulation du potentiel protéolytique tissulaire. Les polysaccharides sulfatés tels que l'héparine, les héparanes sulfate, les dextranes fonctionnalisés ainsi que les fucanes ont de nombreux effets biologiques. Ces molécules sont capables d'agir sur le cycle cellulaire, d'influencer la synthèse de certaines macromolècules matricielles tels que les collagènes ou encore de modifier l'expression et l'activation des métalloprotéases matricielles (MMPs). Le but de nos travaux a été d'étudier l'influence des fucanes, polysaccharides pariétaux d'algues brunes, sur certains paramètres impliqués dans le remodelage tissulaire. Ainsi, nous avons pu montrer que les fucanes étaient capables : d'inhiber la prolifération des fibroblastes gingivaux en culture et à l'inverse d'augmenter celles des fibroblastes dermiques ; d'accélérer la fibrillation des collagènes dans des cultures fibroblastiques ; d'inhiber l'expression des MMPs par des fibroblastes dermiques tout en augmentant la complexation de ces protéases avec leurs inhibiteurs spécifiques (TIMPs) ; d'inhiber directement l'élastase leucocytaire tout en protégeant les fibres élastiques dermiques de l'action de cette sérine protéase. Ce travail qui a fait l'objet d'un dépôt de brevet (n°W09932099) pourrait aboutir au développement de nouveaux composés à partir d'algues brunes capables d'inhiber les effets délétères engendrés par les destructions tissulaires occasionnées lors de pathologies chroniques.

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Thomas, François. "Identification et caractérisation du système alginolytique de la bactérie marine Zobellia galactanivorans." Paris 6, 2011. http://hal.upmc.fr/tel-01110859v1.

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La bactérie marine Zobellia galactanivorans dégrade un grand nombre de polysaccharides de macroalgues. Je me suis intéressé à la dégradation de l'alginate, un composé pariétal des algues brunes. L'annotation du génome a confirmé le potentiel de cette bactérie pour la dégradation de polysaccharides. Z. Galactanivorans possède 7 alginate lyases putatives. Ces gènes sont organisés en deux clusters comprenant d'autres acteurs de la dégradation de l'alginate. J'ai montré que ces clusters sont transcrits au sein d'ARN polycistroniques et constituent des opérons alginolytiques. Une approche transcriptomique ciblée a révélé que l'expression des gènes identifiés dépend de la présence d'alginate. Des analyses de génomique comparative ont montré que cette voie métabolique est conservée chez d'autres bactéries, mettant en évidence des événements de transferts de gènes. La compréhension de l'utilisation de l'alginate a été élargie par un profilage transcriptomique à l'échelle du génome chez Z. Galactanivorans. Il a permis d'identifier d'autres gènes répondant à la présence d'alginate et pouvant participer à la perception, la prise en charge ou la dégradation du substrat. J'ai entrepris une stratégie de clonage sur 21 gènes impliqués dans l'utilisation de l'alginate. Deux nouvelles alginate lyases PL7 de Z. Galactanivorans ont ensuite été surexprimées chez E. Coli, purifiées et cristallisées. Leur spécificité et mode d'action ont été étudiés, menant à l'identification d'AlyA1 comme endo-guluronate lyase et AlyA5 comme exo-guluronate lyase. Leurs structures 3D ont été résolues. Tous les résultats ont été intégrés pour proposer un modèle de système alginolytique chez Z. Galactanivorans

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Albakosh, Mouna Abdalhamed. "Identification and characterization of microorganisms associated with marine macroalgae Splachnidium rugosum." University of the Western Cape, 2014. http://hdl.handle.net/11394/4711.

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>Magister Scientiae - MSc
Marine macroalgae are known to carry diverse bacterial communities which interact with their hosts in both harmful and beneficial ways. Algae hosts provide the bacteria with a rich source of carbon in the form of carbohydrate polysaccharides such as fucoidan, agar and alginate, which the bacteria enzymatically degrade. Splachnidium rugosum is a brown alga (Phylum: Phaeophyta) that grows exclusively in the Southern Hemisphere along the temperate shores of South Africa, New Zealand and Australia. While several studies have investigated S. rugosum distribution and fucoidan production, the microbiome of S. rugosum remains largely uncharacterized. Thus, the major objective of the present study was to isolate, identify and characterize epiphytic bacterial communities associated with S. rugosum. Algae were sourced from Rooi Els (Western Cape, South Africa) during winter 2012. Culture based methods relied on a range of selective marine media including marine agar, nutrient sea water agar, nutrient agar and thiosulfate-citrate-bile-salts-sucrose agar to determine the composition and uniqueness of bacterial communities associated with S. rugosum. Epiphytic isolates were identified to species level by 16S rRNA gene sequence analysis and encompassed 39 Gram-negative and 2 Grampositive bacterial taxa. Isolates were classified into four phylogenetic groups, Gamma - Proteobacteria, Alpha-Proteobacteria, Firmicutes and Bacteriodetes. Bacteria belonging to the phylum Gamma-Proteobacteria were the most abundant, with Vibrio and Pseudoalteromonas being the dominant genera. Three isolates with low sequence identity (˂97%) to their closest relatives could possibly represent novel species. These isolates were grouped into the genera Shewanella, Sphingomonas and Sulfitobacter. All bacterial isolates (41) were screened for antimicrobial activity against the following test strains: Escherichia coli, Bacillus cereus, Staphylococcus epidermidis, Mycobacterium smegmatis Micrococcus luteus and Pseudomonas putida. Fifteen isolates (36%) displayed antimicrobial activity against one or more of the test strains, while one isolate (Pseudomonas species) showed broad spectrum antimicrobial activity against all the test strains except for E. coli. This study provides the first account of the diversity and composition of bacterial populations on the surface of S. rugosum, and demonstrates the ability of these bacteria to produce antimicrobial compounds. Despite recent advances in metagenomics, this study highlights the fact that traditional culturing technologies remain a valuable tool for the discovery of novel bioactive compounds of bacterial origin.

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Moppert, Xavier. "Études et valorisation de métabolites biosynthétisés par une souche bactérienne, isolée de tapis microbiens "kopara" de Rangiroa, Tuamotu, Polynésie française." Polynésie française, 2006. http://www.theses.fr/2006POLF0005.

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Une souche bactérienne identifée comme Paracoccus zeaxanthinifaceans subsp. Payriae a été isolée à partir de prélèvements réalisés sur des tapis microbiens "kopara" sur les atolls de Polynésie française. Cette souche produit, en conditions de laboratoire, un exopolysaccharide (EPS), un pigment, et des polyhydroxyalcanoates (PHA). L'EPS, de haut poids moléculaire et hautement sulfaté, présente une forte activité amincissante laissant présager de son développement rapide en cosmétique. Ses capacités de rétention de cations métalliques tels que le cuivre (Qmax = 625 mg g-1) et le fer (Qmax = 385 mg g-1) permettent d'envisager un développement dans les domaines de l'environnement et de la santé. Le pigment associé à cet EPS lors de la fermentation, est composé à plus de 90% de all-trans-zéaxanthine de configuration absolue (3R, 3'R). Ce composé optiquement actif est très recherché pour la protection de l'oeil et de la peau face aux rayonnements UV. Enfin les plastiques biodégradables que représentent les PHA sont d'un intérêt majeur en terme d'environnement. Leur mode de production écologique pourrait leur permettre de se substituer à courte échéance aux plastiques synthétiques. Ces résultats représentent la première valorisation d'un microorganisme issu du "kopara" et sont à considérer comme le point de départ d'un nouvel axe d'exploitation des ressources maritimes de la Polynésie
A new bacterical identified as Paracoccus zeaxanthinifaceans subsp. Payriae has been isolated from microbial mats known as "kopara", which are located on several Polynesian atolls. Under laboratories conditions, this strain produces metabolites of biotechnological interest including an exopolysaccharide (EPS), a bacterial pigment determined as zeaxanthin and polyhydroxyalkanoates (PHA). The high molecular weight and highly sulfated (25% w/w) EPS exhibits very interesting biological activities and a further commercial developpement in the cosmetic area or as a slimmimng agent could be expected in the very near future. High heavy metal capacities were determined for both iron and copper and, therefore, this EPS may be useful in treatment of wastes and in other environmental or medical applications. The simultaneous synthesis of pure zeaxanthin in its active optical form could be of a great biotechnological interest for medical or cosmetic applications. Under specific conditions this bacterium was also shown to produce large amounts of polyhydroxyalkanoates with environmental applications. Microbial mats known as "kopara", located on several Polynesian atolls appears to be a source of unusual microorganisms and associated metabolites with biotechnological applications

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Talmont, Franck. "Contribution à l'étude du milieu hydrothermal profond : 1 - Étude de tubes d'annélides et de vestimentifères. 2 - Étude structurale d'un exopolysaccharide sécrété par une bactérie marine." Lille 1, 1990. http://www.theses.fr/1990LIL10180.

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L'écosystème qui se développe à proximité des sources hydrothermales d'eau profonde possède des caractéristiques physico-chimiques (profondeur, température, pression, présence de métaux lourds) qui en font un milieu très original. Nous avons effectué l'étude biochimique des tubes et mucus de 4 vers caractéristiques du milieu hydrothermal profond : Riftia pachyptila et Tevnia jerichonana (Vestimentifères), Alvinella pompejana et Paralvinella sp (Annélides polychètes). Les tubes des 2 vestimentifères sont constitués en proportion égale de protéines et de glucides composés en majorité par de la chitine. On observe également des quantités non négligeables d'oses neutres et acides. Le mucus excrété par Paralvinella est très contaminé par le milieu hydrothermal et sa fraction organique ne représente que 10% de la fraction totale. Cette fraction est composée de 60% de glucides pour 40% de protéines. La fraction organique du tube d'Alvinella pompejana contient des monosaccharides méthyles originaux : le 2 et le 3-mono-O-méthyl-L-fucose qui sont caractérisés pour la première fois dans le règne animal, ainsi que le 2,4-di-O-méthyl-L-fucose qui est caractérisé pour la première fois dans la nature. Nous avons également isolé, purifié et partiellement caractérisé un polysaccharide excrété par une bactérie qui se développe au niveau de l'épiderme d'Alvinella pompejana. Ce polysaccharide, très anionique, est homogène en électrophorèse sur gel d'agarose et possède un poids moléculaire de 1100 kDa. Il est formé de glucose, galactose, 4,6-0-(1-carboxyéthylidène) galactose, d'acides glucuronique et galacturonique dans les rapports molaires 4, 3, 1, 3, 1. L'utilisation des méthodes d'approche des séquences oligosaccharidiques (en particulier la FAB-CID-MS-MS) nous permettent de tirer des conclusions partielles quant à la structure de cet exopolysaccharide. Celui-ci semble très branché et possède des séquences riches en acides uroniques telles que : HexUA-HexUA-HexUA-Hex-Hex.

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Akoumany, Katy. "Dérivés de l'exopolysaccharide d’Alteromonas infernus, mimétiques de glycosaminoglycanes, et développement d'une stratégie pour leur analyse structurale." Thesis, Nantes, 2019. http://www.theses.fr/2019NANT4082.

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Dans le cadre de la recherche de nouvelles molécules d’intérêt biotechnologique, les bactéries marines représentent une source considérable de molécules innovantes. L’EPS bactérien, produit par la bactérie Alteromonas infernus est un hétéropolysaccharide anionique de haut poids moléculaire et dont la chaîne osidique est ramifiée. Cette macromolécule et ses dérivés de bas poids moléculaire (obtenus via un procédé chimique) possèdent des propriétés glycosaminoglycanes-mimétiques telles que des activités anti-coagulantes, anti-métastasiques ou favorisant la différenciation cellulaire.Afin d’identifier les motifs moléculaires impliqués dans l’activité biologique et de faciliter l’analyse structurale des dérivés bioactifs (~20 000 g/mol), la préparation de fragments de l’EPS a été entreprise d’une part par synthèse organique et d’autre part par dépolymérisation enzymatique de l’EPS natif. La première partie de la thèse est consacrée à la synthèse organique d’une partie de l’unité répétitive de l’EPS. Les voies de synthèse des donneurs et accepteurs de glycosyles ont été mises au point et deux disaccharides protégés ont été obtenus.Le second volet de la thèse a consisté à préparer des oligosaccharides ainsi que des dérivés de bas poids moléculaires par dépolymérisation enzymatique de l’EPS natif. Une nouvelle génération de dérivés de bas poids moléculaire de l’unité répétitive a été préparée et un nouvel octasaccharide doublement sulfaté a pu être caractérisé par spectrométrie de masse
In search of new bioactive compounds, marine bacteria constitute a considerable source of innovative molecules. The bacterial exopolysaccharide (EPS), produced by the deep-sea hydrothermal vent strain Alteromonas infernus, is a high molecular weight, highly branched and anionic heteropolysaccharide with a nonasaccharide repeating unit. This macromolecule and its low-molecular-weight derivatives obtained through a chemical process have previously displayed interesting GAG-like properties such as anti-metastatic and anti-coagulant (heparin-like) ones; they can also improve stem cell differentiation.To investigate the molecular bases of the biological activity and to facilitate the structural analysis of the bioactive derivatives (~20 000 g/mol), fragments of the native EPS molecule have been prepared by organic synthesis and enzymatic depolymerisation.The first part of this thesis is dedicated to the synthesis of the disaccharides composing the repeating unit of the EPS. The synthetic pathways to acceptor and donor glycosyls have been developed and two protected disaccharides have been synthetized.The second part is devoted to the preparation of oligosaccharides and low molecular weight derivatives by enzymatic depolymerization of the native EPS. A new generation of low molecular weight derivatives has been produced and a new bisulfated octasaccharide has been characterized by mass spectrometry

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Gao, Qiuju. "Marine biogenic polysaccharides as a potential source of aerosol in the high Arctic : Towards a link between marine biology and cloud formation." Doctoral thesis, Stockholms universitet, Meteorologiska institutionen (MISU), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-72433.

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Primary marine aerosol particles containing biogenic polymer microgels play a potential role for cloud formation in the pristine high Arctic summer. One of the major sources of the polymer gels in Arctic aerosol was suggested to be the surface water and more specifically, the surface microlayer (SML) of the open leads within the perennial sea ice as a result of bubble bursting at the air-sea interface. Phytoplankton and/or ice algae are believed to be the main origins of the polymer gels. In this thesis, we examine the chemical composition of biogenic polymers, with focus on polysaccharides, in seawater and airborne aerosol particles collected during the Arctic Summer Cloud Ocean Study (ASCOS) in the summer of 2008. The main results and findings include: A novel method using liquid chromatography coupling with tandem mass spectrometry was developed and applied for identification and quantification of polysaccharides. The enrichment of polysaccharides in the SML was shown to be a common feature of the Arctic open leads. Rising bubbles and surface coagulation of polymers are the likely mechanism for the accumulation of polysaccharides at the SML. The size dependencies of airborne polysaccharides on the travel-time since the last contact with the open sea are indicative of a submicron microgel source within the pack ice. The similarity of polysaccharides composition observed between the ambient aerosol particles and those generated by in situ bubbling experiments confines the microgel source to the open leads. The demonstrated occurrence of polysaccharides in surface sea waters and in air, with surface-active and hygroscopic properties, has shown their potential to serve as cloud condensation nuclei and subsequently promote cloud-drop activation in the pristine high Arctic. Presumably this possibility may renew interest in the complex but fascinating interactions between marine biology, aerosol, clouds and climate.
At the time of doctoral defence, the following paper was unpublished and had a status as follows: Paper 4: Manuscript

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Adrien, Dit Richard Amandine. "Production pilote de polysaccharides sulfatés issus de macroalgues marines à visées anti-coagulante et cosmétique anti-âge." Thesis, La Rochelle, 2016. http://www.theses.fr/2016LAROS013/document.

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L’entreprise SEPROSYS est une société spécialisée dans le développement de solutions d'extraction et de séparation de molécules. Au cours de l’année 2011, l’entreprise a développé un procédé innovant de séparation et de purification fractionnée de biomolécules issues de macroalgues marines. Ce travail de thèse a pour objectif de trouver des applications aux fractions extraites selon le procédé d’extraction et de purification de la société SEPROSYS, et en particulier la fraction des polysaccharides sulfatés, dans deux domaines distincts : en pharmaceutique pour leur activité anti-coagulante et en cosmétique pour leur activité anti-âge. La première partie de nos travaux se penche sur le potentiel des polysaccharides sulfatés de macroalgues comme anti-coagulants. Pour cela, des extraits aqueux de différentes macroalgues brunes, rouges et vertes ont été préparés et leur activité anti-coagulante a été mesurée. Les algues présentant le meilleur potentiel ont ensuite été traitées au moyen du procédé SEPROSYS® afin de purifier leurs polysaccharides sulfatés et d’étudier leur activité anti-coagulante. De plus, l’objectif de ce travail consiste également à mieux comprendre la relation structure-fonction de l'activité anticoagulante d'ulvanes. A cette fin, des ulvanes issus d’Ulva sp. de pureté élevée ont été produits par le procédé SEPROSYS®, soumis à des modifications chimique (hypersulfatation) et physique (dépolymérisation) et leur activité anticoagulante a été étudiée. La deuxième partie de nos travaux concerne l’évaluation du potentiel de ces macroalgues comme agents actifs utilisables en dermo-cosmétique, en particulier pour leur activité anti-âge. Dans ce but, différentes fractions de macroalgues brunes, rouges et vertes ont été testées sur des lignées cellulaires de fibroblastes dermiques humains et leur effet sur la production de collagène par ces fibroblastes a été étudié. Enfin, le potentiel d’ulvanes extraits d’Uva sp. par le procédé de l’entreprise SEPROSYS pour stimuler la biosynthèse de collagène et d’acide hyaluronique par ces mêmes fibroblastes a été déterminé
SEPROSYS is a company specialized in the development of solutions for the extraction and separation of molecules. In 2011, the company has developed an innovative process of fractionated separation and purification of biomolecules from macroalgae. The purpose of this thesis work is to find applications for the purified fractions from the SEPROSYS® process and in particular the sulfated polysaccharides, for two distinct biological activities : as pharmaceutical for their anti-coagulant activity and as dermo-cosmetics for their anti-aging activity. The first part of our work focus on the potential of sulfated polysaccharides from macroalgae as anti-coagulant agents. To this end, aqueous extracts from brown, red and green macroalgae were prepared and their anti-coagulant activity was measured. The best macroalgae were then processed with the SEPROSYS procedure in order to purify the sulfated polysaccharides and study their activity. Furthermore, one of the objectives of this work was to acquire a better understanding of the structure/anti-coagulant function relationship of ulvans. Ulvans of high purity were extracted from Ulva sp. with the SEPROSYS® process, submitted to chemical (hypersulfatation) and physical (depolymerization) modifications and their anti-coagulant activity was measured. The second part of our work relates to the potential of the macroalgae as active agents to be used in dermo-cosmetics, and, in particular, for their anti-aging activity. Different brown, red and green macroalgae fractions were thus tested on normal human dermal fibroblasts cell lines and their effects on the collagen production were measured. Furthermore, the capacity of different molecular weight ulvans extracted from Ulva sp. to stimulate the collagen and hyaluronan biosynthesis was studied. To this end, we developed an efficient depolymerization procedure using ion exchange resins

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Almutairi, Fahad Mohammed. "A molecular hydrodynamic study of marine based non-digestible fibre polysaccharides considered for use in health products." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28907/.

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Marine polysaccharides have been widely used as a source of nutritional supplement for various therapeutic applications. Uncertainties and significant gaps in our knowledge about the macromolecular properties of these substances have limited their use particularly in the pharmaceutical industries where a detailed understanding of materials used for therapies are essential. Therefore, in order to increase our awareness so as to develop better healthcare and therapies against common diseases it is important to establish a better understanding of molecular properties and interactions. The focus of this thesis has been on carrageenans – materials which have arguably been the greatest source of controversy and disagreement in the past in terms of properties – chitosan and alginate and their relations with other substances (mucins, DNA and other polysaccharides). Firstly the main classes of carrageenan - lambda, kappa and iota - have been characterised in terms of their conformation, size and structural integrity utilizing a variety of hydrodynamic techniques including analytical ultracentrifugation based on sedimentation velocity and equilibrium, size exclusion chromatography coupled to multi angle light scattering (SEC-MALS) and viscometry. Studies have suggested that these marine polysaccharides adopt in general semi-flexible structures in solution in contrast to, for example, mucin glycoproteins which adopt a linear random coil conformation. Such conformation analyses are significant in relation to macromolecular structure–function relationships. In addition, the effect of a wide range of solvent conditions was investigated to provide any evidence of dimerization/double helix formation for the main classes of carrageenan (kappa, iota and lambda) using the principal tools of hydrodynamics supported by micro-differential scanning calorimetry. The study showed that, kappa carrageenan adopted a dimeric form under appropriate experimental conditions whereas iota and lambda carrageenan did not. Then, chitosans of different degrees of acetylation were studied, and these too adopted a semi-flexible conformation, but, as with iota and lambda carrageenan, with no evidence of self-association behaviour. A selected group of interactions involving marine polysaccharides or mucin were then investigated. Strong evidence is provided for a clear interaction was observed between chitosan and two polyanions (DNA and xanthan) using the principle of co-sedimentation, and the relevance of this for DNA condensation phenomena is indicated. The use of lambda carrageenan as a possible replacement for alginate in ternary complexes with konjac glucomannan and xanthan for use in the anti-obesity product PolyGlycopleX®, revealed no improvement compared with the use of alginate. Finally, the interaction between the mucin and PolyGlycopleX® was investigated showing that mucin appeared to reinforce interactions between the components of PolyGlycopleX® at higher ionic strengths than seen previously.

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Hentati, Faiez. "Caractérisations structurales et propriétés rhéologiques des polysaccharides de deux algues marines tunisiennes : Cystoseira compressa et Jania adhaerens." Thesis, Université Clermont Auvergne‎ (2017-2020), 2020. http://www.theses.fr/2020CLFAC003.

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Cystoseira compressa et Jania adhaerens sont deux macro-algues marines de la mer méditerranée bien répandues le long des côtes Tunisiennes et non exploitées. Il ressort de cette étude que ces algues pourraient être utilisées comme une source d’ingrédients fonctionnels d’origine naturelle pour la production de burgers à base de chair de poissons d’eau douce (Barbus barbus). De plus, ces travaux ont conduit à l’obtention d’un fucoïdane (CCF) et un alginate de sodium (CCSA) comme polysaccharides matriciels de C. compressa. CCF (1,05 × 105 g/mol) est un hétérogalactofucane sulfaté (14,65 %) composé d’une chaîne principale de α-(1,3 ; 1,4)-l-Fucp ramifiée (31,84 %) en positions O-4 et O-3 par des monosaccharides terminaux et des chaînes latérales. CCSA (Mw = 1 × 105 g/mol) est composé de 56 % de α-l-GulA (G) et 44 % de β-d-ManA (M) (M/G = 0,77). Ce polyuronide est constitué de 93 % d’homoblocs (FGG = 53 % et FMM = 40 %) et de 6 % d’hétéroblocs (FMG = 3 % et FGM = 3 %). Les analyses rhéologiques et biologiques ont montré que CCF et CCSA présentent un comportement rhéofluidifiant ayant des propriétés de liquide visqueux avec des propriétés antioxydantes. Le polysaccharide issu de J. adhaerens (JSP) est un hétéroxylogalactane de Mw = 8,0 × 105 g/mol et est constitué de résidus disaccharidiques répétitifs de [→3)-β-d-Galp-(1,4)-α-l-Galp-(1→)]n et [(→3)-β-d-Galp-(1,4)-3,6-α-l-AnGalp-(1→)]n substitués principalement en position O-6 des résidus (1,3)-β-d-Galp et en positions O-2 et O-3 des résidus (1,4)-α-l-Galp par des T-β-d-Xylp, de groupements sulfate et/ou méthoxyle. Ce galactane sulfaté possède un comportement pseudoplastique typique d’un fluide viscoélastique, ayant des propriétés de gel faible
Cystoseira compressa and Jania adhaerens are two seaweeds widespread on the Tunisian coasts and were not exploited. They have been used as natural ingredients to produce new canned fish burgers prepared from minced fish of common barbel (Barbus barbus). In addition, this work led to the extraction of a fucoidan (CCF) and a sodium alginate (CCSA) as matrix polysaccharides of C. compressa. CCF (Mw=1.05 × 105 g/mol) was a sulfated (14.65%) heterogalactofucan composed of α-(1,3) and α-(1,4)-linked l-Fucp as main backbone, which could be branched (31.8%) in O-3 and O-4 positions by terminal monosaccharides and side chains. CCSA (Mw = 1 × 105 g/mol) was composed of 56% α-l-GulA (G) and 44% β-d-ManA (M) (M/G = 0.77). The CCSA linear backbone was constituted by 93% of homoblocks (FGG = 53% and FMM = 40%) and 6% of heteroblocks (FMG = 3% and FGM = 3%). Rheological and biological investigations showed that CCF and CCSA solutions exhibited shear-thinning and fluid-like viscoelastic behaviors with antioxidant properties. A sulfated xylogalactan-rich fraction (JSP) was extracted from J. adhaerens. JSP (Mw = 8.0 × 105 g/mol) was mainly constituted by the agaran disaccharidic repeating residues (→3)-β-d-Galp-(1,4)-α-l-Galp-(1→)n and (→3)-β-d-Galp-(1,4)-3,6-α-l-AnGalp-(1→)n mainly substituted on O-6 of (1,3)-β-d-Galp residues and in O-2 and O-3 positions of (1,4)-α-l-Galp residues by T-β-d-Xylp, methoxy and/or sulfate groups. JSP solutions displayed a shear-thinning behavior with a great viscoelasticity character, having weak gel properties

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Sari-Chmayssem, Nouha. "Polysaccharides d’algues d’origine Libanaise de type alginate et ulvane et dérivés amphiphiles obtenus par modifications chimiques : évaluation des propriétés physico-chimiques et biologiques." Rennes, Ecole nationale supérieure de chimie, 2016. http://www.theses.fr/2016ENCR0031.

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Alencar, Poliana de Oliveira Cavalcante. "Polysaccharides obtained from the marine alga Gracilaria caudata J. Agardh: chemical and structural study and antioxidant activity evaluation." Universidade Federal do CearÃ, 2016. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=17159.

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nÃo hÃ
Algas marinhas do filo Rhodophyta sÃo fontes naturais de polissacarÃdeos sulfatados que sÃo amplamente utilizados na indÃstria alimentÃcia e na indÃstria farmacÃutica. O presente trabalho teve como finalidade obter os polissacarÃdeos sulfatados totais da alga marinha vermelha Gracilaria caudata (PSG) por extraÃÃo enzimÃtica, determinar a sua estrutura quÃmica e testar o seu potencial antioxidante. As anÃlises quÃmicas revelaram a presenÃa de 85% de aÃÃcares totais e 1% de proteÃnas contaminantes no extrato obtido. AtravÃs de espectrometria de emissÃo Ãptica com plasma (ICP-OES), os PSG apresentaram 0,9% de Ãtomos de enxofre e um grau de sulfataÃÃo de 0,14%. A massa molar mÃdia dos PSG foi determinada por cromatografia em permeaÃÃo em gel (GPC) e mostrou ser da ordem de 116,51 kDa. Os polissacarÃdeos sulfatados totais foram submetidos a testes de caracterizaÃÃo estrutural atravÃs da anÃlise por espectroscopia de infravermelho com transformada de Fourier e ressonÃncia magnÃtica nuclear (RMN) de prÃton (1H) e carbono (13C), identificando os PSG como galactana do tipo agarana. A atividade antioxidante in vitro dos PSG foi avaliada atravÃs de testes, tais como, ensaios de eliminaÃÃo do radical DPPH, quelaÃÃo do Ãon ferroso e capacidade antioxidante total. Os resultados indicaram que tais polissacarÃdeos possuem capacidade de sequestrar radicais livres de maneira significativa e concentraÃÃo-dependente. A atividade antioxidante in vivo dos PSG foi avaliada em modelo de estresse oxidativo induzido pelo 2,2â-azobis-2-amidinopropano (AAPH) em ratos, com posterior dosagem de marcadores do sistema antioxidante enzimÃtico, como catalase (CAT) e superÃxido desmutase (SOD), alÃm da quantificaÃÃo de marcadores de dano oxidativo, como nitrito e tiol. O resultado demonstrou uma melhora no desequilÃbrio redox pelo aumento da atividade da CAT e aumento da atividade da SOD, com melhor resposta na dose de 3 mg/kg. Devido a estes resultados, os polissacarÃdeos sulfatados obtidos a partir da alga marinha Gracilaria caudata mostram potencial de virem a ser utilizados na indÃstria alimentÃcia e farmacÃutica.
Red algae are natural sources of sulfated polysaccharides, which are widely used in the food and pharmaceutical industries. This study aims to obtain the total sulfated polysaccharides from the red seaweed Gracilaria caudata (PSG) through enzymatic extraction, determine their chemical structure and their antioxidant potential. Chemical analysis revealed that the obtained extract is comprised of 85% total sugars and 1% of contaminating proteins. Through Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), the PSG showed a percentage of 0.9% sulfur atoms and a degree of sulfation of 0.14%. The average molar mass of PSG was determined through gel permeation chromatography (GPC) and was determined as 116.51 kDa. The total sulfated olysaccharides were subjected to structural characterization tests through infrared Fourier transform spectroscopy and C13 and H1 Nuclear Magnetic Resonance (NMR) analysis, identifying the PSG as galactan from the agaran type. The in vitro antioxidant activity of PSG was determined using tests such as elimination of DPPH radical, chelation of ferrous ion and total antioxidant capacity. The results indicated that such polysaccharides have the capacity to scavenge free radicals significantly and in a concentration-dependent maner. The in vivo antioxidant activity of PSG was valuated in an oxidative stress model induced by 2,2'-azobis- -amidinopropane (AAPH) in rats, with subsequent dosage of antioxidant enzyme system markers, such as catalase (CAT) and superoxide dismutase (SOD), and the quantitation of oxidative damage markers such as nitrite and thiol. The results showed an improvement in the redox imbalance through increased CAT activity and increased SOD activity with the best response found at a dose of 3 mg / kg. Because of these results, the sulfated polysaccharide obtained from seaweed Gracilaria caudata shows potential for their being used in the food and pharmaceutical industry.

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Khurshid, Chrow Ahmed. "Characterisation of a novel bioactive complex polysaccharide from a marine invertebrate with potent anticancer and antimalarial activities." Thesis, University of Salford, 2017. http://usir.salford.ac.uk/43742/.

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Considerable excitement has been generated by the discovery of active compounds from marine organisms. These compounds have a remarkable role in cancer treatment, with fewer side effects on general health. Sulphated glycosaminoglycan (GAGs) are present in all animals, vertebrate and invertebrate. They are of proven economic importance, not only in the food industry but also in the pharmaceutical field. The present study identifies the key structural differences between the GAGs isolated from whelk and mammalian GAG and investigates their biological activity in relation to cancer and malaria. Glycans from marine sources are unique in terms of their structure and function. They work as an alternative natural source to provide effective treatment for several types of cancer, especially triple negative breast cancer (TNBC), which is the most aggressive type of cancer with fewer available treatment options. In addition, marine GAGs have a proven influence on malaria, although their mechanisms of action are not fully understood. Several methods have been employed to achieve the aims of this study. The structure of whelk GAG was determined using several analytical techniques such as gel filtration chromatography, ion exchange chromatography, mass spectrometry and nuclei magnetic resonance spectroscopy. Enzymatic depolymerisation was also used to generate a library of fragments; each was then evaluated for its biological activity on cancer growth. Anti-proliferation activity on several cancer cells, including pulmonary adenocarcinoma A459, the MCF-7 ER-positive cell line, overexpression of protein HER2- SKBR3 cell line, the hepatoblastoma-derived cell line (Hep G2), chronic myelogenous leukaemia (K562), TNBC and mammosphere formation in breast cancer subtypes, and on malaria has been investigated in vitro using drug sustainable assays. Focusing on TNBC, the label-free quantitative proteomic approach has been used to gain overall insight into the mechanisms of action of whelk GAG on two TNBC cell lines: MDA-MB-468 and MDA-MB-231. The results from whelk GAG analysis suggest a complex fine structure with a high sulphation levels that is clearly distinct from mammalian GAG. Few impurities were detected within the whelk GAG structure, which exhibits enzymatic resistance; this generated structurally indeterminate fragments. These resistant fragments still have significant biological activity against cancer growth. In vitro assays demonstrated significant inhibition activity of whelk GAG toward all types of cancer cells, mammosphere formation from breast cancer cells and malaria. The mechanisms of action by which whelk GAG inhibits the growth of two TNBC cell lines appear to involve influencing the cell integrin signalling cascade, extracellular organisation pathways including the regulation of fibroblast growth factor FGF signalling and fibroblast growth factor receptors FGFR, cell adhesion and reduced glycolysis metabolism. In addition, whelk GAG affected the cell mitosis pathways by downregulating DNA replication proteins. To our knowledge, this is the first study to identify significant structural differences between whelk GAGs and mammalian GAGs, which helps to explain the structural-functional relationship of marine glycans in inhibiting cancer cell growth. It also examines the biological role of GAGs isolated from whelk as anti-proliferation agents toward a wide variety of cancer cell lines and mammosphere formation in breast cancer. Finally, this study is the first to highlight the unique activity of whelk GAG against malaria infection.

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Bozzi, Laurent. "Production et étude physico-chimique de nouveaux polysaccharides synthétisés par des bactéries marines prélevées dans le milieu hydrothermal profond." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10106.

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Notre travail a porte sur l'etude de la production et des proprietes physicochimiques de nouveaux polysaccharides synthetises par des bacteries marines prelevees dans le milieu hydrothermal profond. Dans un premier chapitre, nous avons presente une etude bibliographique generale des principaux polysaccharides bacteriens. Le deuxieme chapitre comprend une etude preliminaire des proprietes physicochimiques et la classification de 17 polysaccharides. Elle a abouti au choix d'un polymere particulierement interessant (le 1644) pour une etude approfondie. La production en fermenteur du polysaccharide a partir de la bacterie altermonas, souche 1644, est traitee dans le troisieme chapitre ainsi que l'isolement d'un autre polysaccharide produit par cette souche mais donnant un gel dans le milieu de culture. Le 4#e chapitre concerne l'etude en solution du polysaccharide 1644. Nous demontrons que ce polymere est un polyelectrolyte carboxylique. Il possede en presence de nacl un comportement classique de chaine semi-rigide. Par contre, il presente une affinite particuliere pour les ions bivalents ainsi qu'un comportement rheologique original avec ceux-ci. Dans le 5#e chapitre sont exposes les resultats obtenus en phase gel. Le polymere 1644 forme en presence d'ions bivalents tels ca#2#+ un gel elastique et resistant, a notre connaissance unique. Les proprietes mecaniques de ce gel physique sont tres voisines de celles d'un gel chimique et dependent du taux d'ions bivalents fixes au polymere

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Colin, Sébastien. "Développement d'enzymes recombinants issus des bactéries marines P. Carrageenovora et SW5 pour la production d'oligo-fucoïdanes et d'oligo-ë-carraghenane." Compiègne, 2005. http://hal.upmc.fr/tel-01115060.

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Ce travail visait à caractériser et produire deux enzymes originaux hydrolysant d'une part un polysaccharide pariétal d'algue rouge (le γ-carraghénane), et d'autre part un polysaccharide d'algue brune (le fucoïdane). Ces deux endo-hydrolases extracellulaires sont produites par deux bactéries marines saprophytes, P. Carrageenovora, et SW5. Suite à la purification des deux enzymes sauvages, leur[s] gène[s] ont été clonés puis séquencés. L'activité recombinante obtenue par surexpression dans E. Coli a validé les séquences obtenues. L'analyse de ces dernières montre l'architecture modulaire des deux protéines. Cependant, le domaine catalytique de la γ-carraghénase n'a pas pu être identifié. Il s'agit donc d'un membre orphelin des glycoside hydrolases, distinct des carraghénases préalablement caractérisées. A l'inverse, les similitudes partagées par la séquence de la fucoïdanase avec deux autres fucoïdanases, a permis de définir une nouvelle famille de glycoside hydrolases
This work aimed to characterize and produce two new biocatalysts which hydrolyze two polysaccharides extracted from the cell wall of red algae (γ-carrageenan) and brown algae (fucoidan). These extracellular endo-hydrolases are produced by two saprophytic marine bacteria, Pseudoalteromonas carrageenovora, (y-Proteobacteria), and SW5 (Bacteroidetes). Following the purification ofwild-type proteins, their genes were cloned and sequenced. The recombinant activity obtained by overexpression in E. Coli confirmed that the cloned sequences coded for corresponding enzymes. Sequence analysis showed that the enzymes have a modular structure. The catalytic domain of the γ-carrageenase was net identified. This enzyme is therefore different from previously described glycoside hydrolases, and aise distinct from previously known carrageenases. The fucoidanase sequence shares similarity with two other bacterial putative fucoïdanase and these three enzymes define a new glycosidase family

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Kappelmann, Lennart [Verfasser], Rudolf [Akademischer Betreuer] Amann, Rudolf [Gutachter] Amann, and Jens [Gutachter] Harder. "Genomic Analyses of Polysaccharide Utilization in Marine Flavobacteriia / Lennart Kappelmann ; Gutachter: Rudolf Amann, Jens Harder ; Betreuer: Rudolf Amann." Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://d-nb.info/1162620641/34.

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Decamp, Antoine. "Etude des conditions d’accumulation et de production de polysaccharides solubles (ou exopolysaccharides - EPS) chez des microalgues marines cultivées en photobioréacteur." Thesis, Nantes, 2020. http://www.theses.fr/2020NANT4035.

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Cette thèse porte sur l’étude des mécanismes de synthèse des exopolysaccharides de Porphyridium cruentum et l’optimisation de leurs productions en photobioréacteur. Afin de répondre à cet objectif, l’effet de la salinité et de la lumière ont principalement été étudiés. La salinité est un paramètre influençant fortement le métabolisme des carbohydrates de Porphyridium cruentum favorisant la production de biomasse pour une salinité médiane, l’accumulation d’amidon en condition hypo-osmotique et l’accumulation de glycosides (plus particulièrement de floridoside) en condition hyper-osmotique. Le MRPA (Mean rate of Photon Absorption) a été utilisé afin d’évaluer le comportement de la microalgue rouge en condition de stress lumineux ainsi qu’en photo limitation. La première partie de cette étude a permis de montrer que Porphyridium cruentum est un organisme sensible à la lumière, présentant une section efficace d'absorption 7 fois inférieure à la microalgue verte Chlorella vulgaris. Dans une deuxième partie, différents niveaux de stress lumineux ont été imposés à la microalgue rouge, les résultats ont démontré qu’à partir d’une valeur seuille l’augmentation du MRPA permet d’accélérer fortement la production de polysaccharides (sous forme d’amidon et de BPS dans un premier temps et sous forme de RPS lors d’un stress prolongé). L’association du stress osmotique et lumineux a permis de développer un protocole permettant de valoriser la biomasse de Porphyridium cruentum à façon dans le but de produire en condition hyper-osmotique contrôlée du floridoside ou en condition hypo-osmotique pour des MRPA élevées des polysaccharides
This thesis concerns the study of the mechanisms implicated in Porphyridium cruentum exopolysaccharides synthesis and the optimization of their production in photobioreactors. In order to achieve this objective, the effect of salinity and light were mainly studied. Salinity is a parameter which affect the carbohydrates metabolism of Porphyridium cruentum favouring biomass production at median salinity, starch accumulation in hypo-osmotic conditions and glycoside accumulation (more particularly floridoside) in hyper-osmotic conditions. MRPA (Mean rate of Photon Absorption) was used to evaluate the behaviour of red microalgae in light stress conditions and in photo limitation. The first part of this study showed that Porphyridium cruentum is a light-sensitive organism with an effective absorption cross section 7 times smaller than the green microalgae Chlorella vulgaris. In the second part, different levels of light stress were imposed on the red microalgae, the results showed that from a threshold value the increase in MRPA allows to strongly accelerate the production of polysaccharides (in the form of starch and BPS in a first step and in the form of RPS during a prolonged stress).The combination of osmotic and light stress has made it possible to develop a protocol to valorise the biomass of Porphyridium cruentum in order to produce floridoside in controlled hyper-osmotic conditions or polysaccharides for hypo-osmotic conditions coupling with high MRPA

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Bouhlal, Rhimou. "Activités biologiques de principes actifs de différents extraits d’algues rouges marines (Rhodophyceae) de la côte atlantico-méditerranéenne du Maroc." Lorient, 2010. http://www.theses.fr/2010LORIS176.

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Les potentialités biologiques des algues benthiques des côtes marocaines sont méconnues. Dans le but de la valorisation de cette ressource, une évaluation de l’activité antibactérienne, cytotoxique, antivirale, antioxydante et anti-algale a été réalisée à partir de 130 extraits de polarité différente issus de 29 espèces de Rhodophycées (1 Bonnemaisoniales, 8 Céramiales, 3 Corallinales, 7 Gélidiales, 9 Gigartinales, 1 Rhodymeniales). Les extraits ont été testés contre 11 bactéries Gram-négatif et 10 bactéries Gram-positif par la méthode de diffusion par disque. Soixante-quinze pourcent des extraits sont actifs sur au moins une souche bactérienne. L’évaluation de l’activité antioxydante a été réalisée à travers 3 tests différents. Lors du test au DPPH, 4 extraits méthanoliques ont permis la transformation du radical de DPPH en forme réduite avec une CE50 située entre 96 et 862 µg. ML-1. Dans le cadre du test au β-carotène, 7 extraits méthanoliques ont montré une activité contre les radicaux peroxydes avec une CE50 entre 9 et 176 µg. ML-1. Dans le test au désoxyribose, le pourcentage d’inhibition des radicaux du groupe hydroxyle varie entre 25 et 68% pour 5 extraits aqueux dont le plus important est l’extrait d’Asparagopsis armata. L’évaluation de l’activité antialgale vis-à-vis des Diatomophycées, Cylindrotheca fusiformis, C. Closterium et Amphora coffeaeformis, par l’analyse de la chlorophylle-a a montré que la concentration effective 50% varie entre des valeurs inférieures à 10 µg. ML-1 et d’autres supérieures à 1000 µg. ML-1. L’évaluation de l’activité antivirale sur le modèle virus d’Herpes simplex de type-1/Cellules Véro par viabilité cellulaire met en évidence que les extraits aqueux sont capables d'empêcher in vitro la réplication de VHS-1 à une CE50 (concentration effective 50%) qui varie de <2,5 à < 75,9 µg. ML-1. Aucun effet cytotoxique n’a été observé avec les extraits aqueux sur les cellules Véro dans la gamme des concentrations étudiées 2,5 et 250,0 µg. ML-1. Deux polysaccharides sulfatés isolés de Sphaerococcus coronopifolius (Gigartinales) et Boergeseniella thuyoides (Céramiales) respectivement présentent in vitro une inhibition de la réplication de Virus de l'Immunodéficience Humaine (VIH) par mesure de l’enzyme transcriptase inverse dans les cellules CEM et la formation de syncitia dans les cellules MT4 après 3 jours à 12,5 µg. ML-1. Ils sont aussi capables d’inhiber également in vitro la réplication du VHS-1 dans les cellules Véro avec une concentration effective (CE50), respectivement, de 4,1 à 17,2 µg. ML-1. Aucune toxicité supérieure à 200,0 µg. ML-1 n’a été observée sur les cellules Véro et MT4. L’activité des polysaccharides contre le VIH-1 et le VHS-1 se manifeste juste après l’infection. La purification par Chromatographie de Partage Centrifuge (CPC) de l’extrait chloroforme-méthanol d’Asparagopsis armata a permis d’obtenir des fractions contenant deux à quatre composés. Les techniques de résonance magnétique nucléaire (RMN) et la spectrométrie de masse (SM) ont mis en évidence la présence des acides gras, des acides aminés et des composés aromatiques. Des signaux de phénols et des composés polysaccharidiques ont également été caractérisés. La présence continue des acides gras dans toutes les fractions actives analysées, nous permet de déduire qu’ils pourraient contribuer dans l’activité antibactérienne
The biological potentialities of seaweeds benthic of the Moroccan coast are not recognized. With the aim of the valuation of this resource, an evaluation of the antibacterial activity, cytotoxic, antiviral, antioxidant and anti-algal was realized from 130 extracts of different polarity stemming from 29 species of Rhodophyceae (1 Bonnemaisoniales, 8 Ceramiales, 3 Corallinales, 7 Gelidiales, 9 Gigartinales, 1 Rhodymeniales). Extracts were tested against 11 bacteria Gram-negatives and 10 bacteria Gram-positives by the method of diffusion by disk. Seventy-five percent of the extracts are active on at least a bacterial strain. The evaluation of the antioxidant activity was realized through 3 different tests. During the test in the DPPH, 4 methanolic extracts allowed the transformation of the radical of DPPH in shape reduced with EC50 situated between 96 and 862 µg. ML-1. Within the work of the test in β-carotene, 7 methanolic extracts showed an activity against the peroxide radicals with EC50 between 9 and 176 µg. ML-1. In the test in the deoxyribose, the percentage of inhibition of the radicals of the group hydroxyls varies between 25 and 68 % for 5 aqueous extracts, of which most important is the extract of Asparagopsis armata. The evaluation of the anti-algal activity towards Diatomophyceae, Cylindrotheca fusiformis, C. Closterium and Amphora coffeaeformis, by the analysis of chlorophyll-a showed that the effective concentration 50 % varies between values lower than 10 µg. ML-1 and the other superiors in 1000 µg. ML-1. The evaluation of the antiviral activity on the model virus of Herpes simplex of type-1 / Vero cells by cellular viability revealed that the aqueous extracts are capable of preventing in vitro the replication of VHS-1 in a EC50 (effective concentration 50 %) which varies of < 2. 5 at < 75. 9 µg. ML-1. No cytotoxic effect was observed with the aqueous extracts on Vero cells in the range of the studied concentrations 2. 5 and 250µg. ML-1. Two sulfated polysaccharides isolated of Sphaerococcus coronopifolius (Gigartinales) and Boergeseniella thuyoides (Ceramiales) present in vitro an inhibition of the replication of Human Immunodeficiency Virus (HIV) respectively by measure of the reverse transcriptase enzyme in cells CEM and formation of syncitium in cells MT4 after 3 days in 12. 5 µg. ML-1. They are also capable of inhibiting also in vitro the replication of the HSV-1 in cells Vero with an effective concentration (EC50), respectively of 4. 1 and 17. 2 µg. ML-1. No toxicity superior to 200. 0 µg. ML-1 was observed on Vero cells and MT4. The activity of polysaccharides against the HIV-1 and the HSV-1 appears just after the infection. The purification by Centrifugal Partition Chromatography (CPC) of the chloroform-methanol extract of Asparagopsis armata allowed obtaining containing fractions two in four compounds. The techniques of nuclear magnetic resonance (NMR) and the mass spectrometry (MS) revealed the presence of fatty acids, amino acids, aromatic compounds. Signals of phenols and polysaccharidic compounds also characterized. The continuous presence of the fatty acids in all the analyzed active fractions allows us to deduct that they could contribute in the antibacterial activity

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Reintjes, Greta [Verfasser], Bernhard [Akademischer Betreuer] Fuchs, Rudolf [Gutachter] Amann, and Carol [Gutachter] Arnosti. "Taxonomic and Functional Analyses of Marine Microbial Polysaccharide Utilisation / Greta Reintjes ; Gutachter: Rudolf Amann, Carol Arnosti ; Betreuer: Bernhard Fuchs." Bremen : Staats- und Universitätsbibliothek Bremen, 2017. http://d-nb.info/113571617X/34.

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Francis, Ben [Verfasser], Thomas [Akademischer Betreuer] Schweder, Thomas [Gutachter] Schweder, Dirk [Gutachter] Schüler, Mirjam [Gutachter] Czjzek, and Rudolf [Gutachter] Amann. "Proteogenomics of Marine Polysaccharide Utilisation / Ben Francis ; Gutachter: Thomas Schweder, Dirk Schüler, Mirjam Czjzek, Rudolf Amann ; Betreuer: Thomas Schweder." Greifswald : Universität Greifswald, 2021. http://d-nb.info/1227581408/34.

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Francis, Ben [Verfasser], Thomas Akademischer Betreuer] Schweder, Thomas [Gutachter] Schweder, Dirk [Gutachter] [Schüler, Mirjam Gutachter] Czjzek, and Rudolf [Gutachter] [Amann. "Proteogenomics of Marine Polysaccharide Utilisation / Ben Francis ; Gutachter: Thomas Schweder, Dirk Schüler, Mirjam Czjzek, Rudolf Amann ; Betreuer: Thomas Schweder." Greifswald : Universität Greifswald, 2021. http://d-nb.info/1227581408/34.

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Francis, Ben [Verfasser], Thomas [Akademischer Betreuer] Schweder, Thomas Gutachter] Schweder, Dirk [Gutachter] [Schüler, Mirjam Gutachter] Czjzek, and Rudolf [Gutachter] [Amann. "Proteogenomics of Marine Polysaccharide Utilisation / Ben Francis ; Gutachter: Thomas Schweder, Dirk Schüler, Mirjam Czjzek, Rudolf Amann ; Betreuer: Thomas Schweder." Greifswald : Universität Greifswald, 2021. http://nbn-resolving.de/urn:nbn:de:gbv:9-opus-43126.

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Caporiccio, Bertrand. "Recherche sur quelques activités biologiques d'un polysaccharide sulfate acide : extrait et caractérisé chez une algue marine Asparagopsis armata (Rhodophycee, Bonnemaisoniale)." Perpignan, 1994. http://www.theses.fr/1994PERP0185.

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On a isole chez une algue rouge marine asparagopsis armata, une substance polysaccharidique qui a recu le nom d'armatan. Nous avons etudie sa localisation dans le thalle, mis en evidence certaines de ses activites biologiques et suivi sa cinetique dans l'organismeanimal. ? les methodes histochimiques specifiques precisent sa localisation a l'interieur du thalle. L'armatan possede une activite antitumorale, mitogene et hypocoagulante. ? il augmente de 22,5% la survie des souris c3h porteuses d'un carcinome mammaire. ? il provoque la transformation blastique des lymphocytes humains et murins, avec un role plutot t activateur chez l'homme. ? il allonge le temps de coagulation plasmatique in vitro et in vivo chez l'animal. Son efficacite hypocoagulante semble maximale par voie sous-cutanee. Il intervient sur la voie intrinseque de la coagulation. Son administration intra-veineuse produit des effets adverses en particulier sur le foie, la rate et les hematies. L'injection a l'animal d'un armatan marque au #1#4c, obtenu par culture permet de preciser son trajet dans l'organisme. Il ne sejourne pas dans le plasma mais est elimine assez rapidement dans les urines ou les feces. Cette experience permet de montrer que l'armatan se fixe comme l'heparine sur l'endothelium vasculaire

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Robic, Audrey. "Etude de la variabilité chimique, physico-chimique et rhéologique des ulvanes, polysaccharides des parois cellulaires d'algues marines vertes de la famille des Ulves (Ulvales, Chlorophyta)." Nantes, 2008. http://www.theses.fr/2008NANT2104.

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Les algues vertes appartenant aux genres Ulva et Enteromorpha sont communes à travers le monde. Elles prolifèrent localement sous la forme de « marées vertes » et sont source de nuisances. Elles sont riches en polysaccharides parmi lesquels les ulvanes représentent par leurs caractéristiques chimiques et gélifiantes un atout pour valoriser ces algues. Le rendement d’extraction, la variabilité chimique, physico-chimique et rhéologique d’ulvanes d’algues contribuant aux marées vertes (U. Rotundata et U. Armoricana) ont été étudiés en fonction de la période de récolte et du mode de conservation des algues. Les rendements sont maximum à partir d’U. Rotundata en croissance, à la fin de la période de prolifération d’U. Armoricana et à partir d’algues saumurées. La proportion des deux populations moléculaires constitutives des ulvanes est affectée par la période de collecte et le mode de conservation. Des masses élevées sont obtenues à partir d’algues récoltées en période de croissance et conservées par congélation. Le module de conservation des gels d’ulvane est positivement corrélé avec la proportion d’ulvanes de haute masse et la teneur en rhamnose, en acide glucuronique et en sulfate. Parmi différentes conditions d’extractions étudiées, une solution diluée d’acide chlorhydrique à chaud donne un rendement optimal. Des études par microscopie indiquent que les ulvanes ont un caractère hydrophobe marqué conduisant à des structures moléculaires sphériques expliquant les faibles viscosités développées par ces polysaccharides. La gélification des ulvanes en présence d’acide borique et de cations divalents résulterait de l’agrégation de ces sphères
Green seaweeds belonging to Ulva and Enteromorpha species are common worldwide. Collected or cultivated for human consumption, they proliferate in the form of “green tides” and result in harmful accumulations. They are rich in polysaccharides and notably in the water soluble ulvan which presents original chemical and gelling properties and afford novel opportunities for the biomass uses. The impact of the period of collect and stabilization treatments on the extraction yield, chemical, physico-chemical and rheological variability of ulvan from species contributing to Brittany “green tides” (U. Rotundata and U. Armoricana) were studied. The highest yields were obtained from actively growing U. Rotundata, from U. Armoricana at the end of the proliferation period and from brined seaweeds. The period of collect and the stabilization treatment affected the proportion of the two macromolecular populations constituting ulvans. The highest molecular weight ulvan was obtained from actively growing seaweeds and stored frozen. The storage modulus of ulvan gels was positively correlated with the proportion of high molecular weight ulvan and with the rhamnose, glucuronic acid and sulfate contents. Among different extraction conditions studied, hot dilute chlorhydric acid solution gave an optimal extraction yield. Microscopic studies indicated that ulvans are hydrophobic which led to the formation of spherical molecular structures that explain the low intrinsic viscosities of ulvan in solution. The gelling properties of ulvan with boric acid and divalent cations would arise from the association of these globules

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Jaulneau, Valérie. "Caractérisation moléculaire d'un extrait d'algues vertes, stimulateur des défenses des plantes contre les agents pathogènes." Toulouse 3, 2010. http://thesesups.ups-tlse.fr/2603/.

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La capacité des plantes à se défendre contre les parasites dépend de la perception d'éliciteurs qui induisent les défenses des plantes. Afin de les utiliser comme méthode alternative pour contrôler les maladies, il est nécessite d'identifier des sources abondantes et de caractériser leur activité. Au cours de ce travail, nous avons identifié un nouveau polysaccharide extrait d'algue verte, Ulva spp. , et caractérisé son activité biologique. Les molécules présentes dans l'extrait ont été séparées par leur poids moléculaire (PM). Seule la fraction de haut PM, qui contient essentiellement un polysaccharide sulfaté appelé ulvane, possède une activité. Les effets des ulvanes sur le transcriptome de M. Truncatula ont été comparés à ceux du méthyl jasmonate (MeJA) et de l'acibenzolar-S-methyl. La signature transcriptomique obtenue en réponse aux ulvanes présente de nombreuses similitudes à celle obtenue en réponse au MeJA. Ces deux traitements induisent des réponses régulées par la voie du JA telle que l'activation des inhibiteurs de protéases. L'expression de gènes dépendants cette voie est aussi induite chez A. Thaliana en réponse aux ulvanes. Enfin, les ulvanes entraînent une inhibition de la croissance in-vitro, qui est partiellement affectée chez le mutant PEPR2. L'efficacité protectrice de l'extrait brut a été testée contre divers parasites. Ainsi, il protège contre les oomycetes et les champignons responsables, respectivement, d'oïdium et de mildiou. Nos résultats montrent que les ulvanes induisent les défenses des plantes via la voie du JA et soulignent l'intérêt des outils d'analyse transcriptomique pour identifier de nouveaux éliciteurs capables de protéger les plantes
The ability of plants to defend themselves against pathogens depends on the perception of elicitors, which induce plant defence. They might be considered as alternative tools for disease control in agronomic crops. Their industrial use needs to identify abundant sources and characterize their activity. Here we report on the identification of a new polysaccharide purified from the green algae Ulva spp. And the characterization of it biological activity in plants. Molecules contained in the extract were sized-fractionated. Analyses of the fractions revealed that biological activity was present only in the fraction of high molecular weight which contained most exclusively a sulfated polysaccharide named ulvan. Response to ulvan were compared to those induced upon methyl jasmonate (MeJA) and acibenzolar-S-methyl on the legume M. Truncatula using microarrays. Interestingly, ulvan gene expression signature showed significant similarity to MeJA and typical responses controlled by the JA pathway, such as induction of protease inhibitor activity. Expression of JA responsive genes, like PDF1. 2, was also induced in A. Thaliana after ulvan treatment. Ulvan provoked an inhibition of in-vitro growth, which was partially impaired in the mutant PEPR2. The efficient protection induced by the crude extract was tested against pathogens on various crops. So, it protect well against oomycetes and fungus that respectively cause downy and powdery mildews. Our results show that ulvan induces plant defences through the jasmonate signalling pathway and highlight the use of functional genomics to develop new bioactive compounds for plant protection

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QuinderÃ, Ana LuÃza Gomes. "Propriedades na nocicepÃÃo e na inflamaÃÃo de uma fraÃÃo polissacarÃdica sulfatada da alga marinha Acanthophora muscoides." Universidade Federal do CearÃ, 2011. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7577.

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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
No presente trabalho, uma fraÃÃo polissacarÃdica sulfatada obtida da alga marinha Acanthophora muscoides (AmII) foi avaliada atravÃs de modelos de nocicepÃÃo e inflamaÃÃo. A toxicidade sistÃmica dos polissacarÃdeos sulfatados totais tambÃm foi analisada. A atividade antinociceptiva foi avaliada atravÃs dos ensaios de contorÃÃes abdominais induzidas por Ãcido acÃtico, teste da formalina e da placa quente. Camundongos Swiss machos foram tratados com AmII (1, 3 ou 9 mg/kg; i.v.) 30 min antes de receber injeÃÃo de Ãcido acÃtico 0,8% ou formalina 1% ou antes da exposiÃÃo a um estÃmulo tÃrmico. AmII reduziu significativamente o nÃmero de contorÃÃes abdominais induzidas por Ãcido acÃtico e o tempo lambedura da pata na segunda fase do teste da formalina. No teste da placa quente, AmII nÃo prolongou o tempo de reaÃÃo dos animais. A atividade antiinflamatÃria foi avaliada atravÃs do ensaio de migraÃÃo de cÃlulas atravÃs da cavidade peritoneal induzida por carragenana (700 μg/ cavidade) e dos ensaios de edema de pata induzidos por carragenana (500 μg/pata) ou por dextrano (400 μg/pata). Ratos Wistar foram tratados com AmII (1, 3 ou 9 mg/kg; s.c.) 60 min antes do estÃmulo inflamatÃrio. AmII reduziu significativamente a migraÃÃo de neutrÃfilos atravÃs da cavidade peritoneal. No ensaio do edema de pata induzido por carragenana, AmII nÃo reduziu a formaÃÃo do edema e a migraÃÃo neutrofÃlica, analisada atravÃs da determinaÃÃo dos nÃveis teciduais de mieloperoxidase. Entretanto, AmII inibiu o edema de pata induzido por dextrano no primeiro intervalo analisado. Adicionalmente, quando AmII (500 μg) foi injetada (s.c.) na pata, para verificar um possÃvel efeito edematogÃnico, nÃo foi observado edema. No ensaio de toxicidade subcrÃnica, camundongos foram tratados diariamente durante 14 dias com os polissacarÃdeos sulfatados totais de A. muscoides (20 mg/kg; i.p.). Sinais consistentes de dano sistÃmico nÃo foram observados, conforme revelado pela avaliaÃÃo do peso corporal e dos ÃrgÃos fÃgado, rim, coraÃÃo, baÃo, timo, e linfonodo e das anÃlises bioquÃmicas, hematolÃgicas e histopatolÃgicas. Como conclusÃo, a fraÃÃo AmII possui propriedades antinociceptiva e antiinflamatÃria e representa um potecial agente terapÃutico, justificando estudos futuros.
Herein, a sulfated polysaccharidic fraction obtained from the marine alga Acanthophora muscoides (AmII) was evaluated using models of nociception and inflammation. The systemic toxicity of the total sulfated polysaccharides was also assessed. The antinociceptive properties were assayed using the writhing test induced by acetic acid, the formalin and the hot plate test. Swiss mice were treated with AmII (1, 3 or 9 mg/kg; i.v.) 30 min prior to either receiving an injection of 0.8% acetic acid or 1% formalin or prior to a thermal stimulus. AmII reduced the number of acetic acid-induced writhes and licking time in the second phase of the formalin test, but it did not alter the response latency in the hot plate test. The anti-inflammatory properties were assayed using the carrageenan-induced neutrophil migration into the peritoneal cavity and carrageenan- or dextran-induced paw edema models. Wistar rats were treated with AmII (1, 3 or 9 mg/kg; s.c.) 60 min prior to inflammatory stimuli. AmII reduced significantly the neutrophil migration into the peritoneal cavity. In the carrageenan-induced paw edema, AmII did not reduce the edema formation or the neutrophil migration, as assessed by the determination of myeloperoxidase levels in the paw tissue. However, AmII reduced dextran-induced paw edema during the first interval analysed. Furthermore, when AmII (500 μg) was injected (s.c.) into the paw, to verify a possible edematogenic effect, no edema was observed. Additionally, when mice were treated with the total sulfated polysaccharides from A. muscoides (20 mg/kg; i.p.) for 14 days, no consistent signs of systemic damage were observed, as revealed by body weight, liver, kidney, heart, spleen, thymus and lymph node wet weight and by biochemical, hematological and histopathological analyses. In conclusion, AmII has antinociceptive and anti-inflammatory properties and represents a potencial therapeutic agent warranting future studies.

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AraÃjo, Glacio Souza. "Immunostimulant effect of sulfated polysaccharides from the red marine alga Gracilaria caudata in sexual reversion of Nile tilapia, Oreochromis niloticus (LINNAEUS, 1766) under adverse conditions." Universidade Federal do CearÃ, 2006. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=351.

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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
Machos de tilÃpia chegam a crescer de 1,8 a 2,5 vezes mais rÃpido do que as fÃmeas, sob condiÃÃes de cultivo intensivo. Assim, as estratÃgias para obter populaÃÃes monossexo estÃo focadas na produÃÃo de lotes de alevinos machos. A produÃÃo de indivÃduos 100% machos atravÃs do uso do andrÃgeno 17-α-metiltestosterona Ã considerada a tÃcnica mais efetiva e de menor custo. No entanto, o uso de hormÃnios e o aumento na densidade de cultivo tendem a afetar adversamente a saÃde dos organismos cultivados, aumentando os Ãndices de mortalidade. O objetivo deste trabalho foi avaliar o efeito de polissacarÃdeos sulfatados, extraÃdos da alga marinha vermelha Gracilaria caudata, na sobrevivÃncia e ganho de peso de pÃs-larvas da tilÃpia do Nilo, Oreochromis niloticus, submetidas Ã reversÃo sexual. O experimento consistiu em quatro tratamentos com trÃs repetiÃÃes cada, em um total de doze aquÃrios com capacidade para 40L. Em cada tratamento foram utilizadas 960 pÃs-larvas (plâs) de tilÃpias, na densidade de estocagem de 8 plâs/L. No tratamento controle nÃo foi utilizado o polissacarÃdeo e, nos outros trÃs tratamentos, foram utilizadas doses crescentes (0,05, 0,1 e 0,2mg/g de peso vivo das larvas) do polissacarÃdeo na raÃÃo. Durante as duas primeiras semanas de reversÃo, foi utilizada aeraÃÃo constante e uma renovaÃÃo de Ãgua de 20% em cada repetiÃÃo. A partir da terceira semana, foi elevado o estresse em todos os tratamentos atravÃs da supressÃo da aeraÃÃo e/ou da renovaÃÃo de Ãgua, a fim de induzir o aumento da mortalidade. Ao final do experimento, nÃo houve diferenÃa significativa entre os tratamentos com relaÃÃo ao peso mÃdio final e ganho mÃdio de peso diÃrio das pÃs-larvas. No entanto, com relaÃÃo Ã mortalidade, houve diferenÃa significativa (α = 0,05) no final ao final da Ãltima semana de reversÃo e cinco dias apÃs o experimento (α = 0,01), quando o estresse foi de moderado a elevado, respectivamente. Desta forma, as plâs que receberam a dose de 0,1 e 0,2mg/g se tornaram mais resistentes Ãs situaÃÃes de estresse induzidas no experimento.
Under intensive culture conditions males of tilapia grow 1.8 to 2.5 times faster than females. Thus, strategies to get monosex populations are concentrated on male production fingerlings lots. The production of 100% males individuals through the use of the androgen 17-α-methyl-testosterone is considered the most effective and lesser cost technique. However, hormone administration and culture density enhan cement tend to adversely affect cultivated organisms health, increasing mortality indices. The aim of this work was to evaluate the effect of sulfated polysaccharides extracted from the red marine alga Gracilaria caudata in the Nile tilapia, Oreochromis niloticus, post-larvae (pl's) survival and weight gain submitted to sexual reversion. The experiment consisted of four treatments with three repetitions in twelve 40L capacity aquariums. In each treatment were used 960 tilapias pl's in a stockage density of 8 pl's/L. In the control treatment was not used the polysaccharide and in the others three ones were used increasing doses (0.05,0.1 and 0.2mg/g live weight) of the polysaccharide in the ration. During the two first weeks of reversion a constant aeration and a 20% water exchange were done in each treatment. In order to induc e mortality, stress was raised in all treatments by aeration and/or water exchange suppression from the th ird week until the end of the experiment. Final mean weight and daily mean weight gain of pl's in all treatments did not showed significant difference at a 5% level. However, pl's mortality showed significant difference at the end of the last week of reversion (α = 0.05) and at the end of the last five days of the experiment (α = 0.01), when stress was raised of moderate to elevated, respectively. Then, pl's that received the polysaccharides doses of 0.1 and 0.2mg/g live weight became more resistant to stress situations induced in the experiment.

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Klein, Cécile. "Etude des dynamiques du phytoplancton en Manche orientale et occidentale : Approche écophysiologique : [thèse soutenue sur un ensemble de travaux." Caen, 2010. http://www.theses.fr/2010CAEN2016.

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Deux sites contrastés de la Manche où les activités conchylicoles sont importantes (la Baie des Veys -BDV- et Lingreville-sur-mer -LGV- côtes Est et Ouest du Cotentin) ont été étudiés. La variabilité temporelle (saisonnière à pluriannuelle) des communautés phytoplanctoniques, de la production primaire et des paramètres photosynthétiques a été analysée en fonction des forçages environnementaux à l’aide d’analyses multivariées. Les deux sites étudiés ont montré des dynamiques phytoplanctoniques différentes. Au site BDV, celle-ci a suivi un cycle saisonnier dépendant de la température, de la lumière et des stocks de sels nutritifs tandis qu’au site LGV, cette dynamique est affectée par l’hydrodynamisme (vent, courants de marée). Cette étude a également démontré que l’assemblage phytoplanctonique était dominé par des espèces différentes en fonction des années traduisant l’existence d’une compétition interspécifique permanente où l’évolution des paramètres environnementaux et les capacités physiologiques de chaque espèce jouent un rôle essentiel. Pour comprendre le devenir des efflorescences dans la colonne d’eau, un suivi temporel des excrétions de polysaccharides (EPS) a été effectué. La quantification de ces excrétions en fonction des variables environnementales a montré une influence de l’azote (NO3, NH4) au printemps et de l’hydrodynamisme en automne sur ces excrétions. Une attention particulière a également été portée sur la succession des Pseudo-nitzschia spp au site BDV démontrant la présence de 6 espèces et le développement possible d’une espèce toxique, P. Australis, en automne lorsque les températures sont fortes et qu’une limitation en Si est observée
Two contrasted areas of the English Channel which show important shellfish farming (Baie des Veys -BDV- and Lingreville-sur-mer -LGV- Eastern and Western coasts of Cotentin) have been studied. The temporal variations (seasonal to long-term) of phytoplankton communities, primary production and photosynthetic parameters have been analysed according to environmental forces using multivariate analyses. A different phytoplankton dynamic between the two studied sites was observed. At the BDV site, it followed a seasonal cycle dependant on temperature, light and nutrients stocks whereas at the LGV, this dynamic was largely dependant on hydrodynamism (wind, tidal currents). This study has also demonstrated that phytoplankton assemblage was dominated by different species according to the year illustrating a continuous interspecific competition controlled by environmental parameters variations and by physiological capacities of each species. To understand the mechanisms of the end of phytoplankton bloom in the water column, a time series of the extracellular polymeric substances (EPS) was made. The quantification of those excretions according to environmental parameters showed that EPS were affected by nitrogen concentrations (NO3, NH4) in spring and by hydrodynamic forces in autumn. The Pseudo-nitzschia spp succession at the BDV site was finally studied, indicating the occurrence of 6 species and the possible development of a toxic species, P. Australis, in autumn when temperatures are high and a Si limitation is observed

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Depont, Mélanie. "Criblage de bactéries productrices d'enzymes (fucosidase et fucoïdane hydrolase) capables de dégrader les fucoïdanes." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27062/27062.pdf.

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Krüger, Karen [Verfasser], Rudolf [Akademischer Betreuer] Amann, Rudolf [Gutachter] Amann, and Carol [Gutachter] Arnosti. "Polysaccharide utilization loci and associated genes in marine Bacteroidetes - compositional diversity and ecological relevance / Karen Krüger ; Gutachter: Rudolf Amann, Carol Arnosti ; Betreuer: Rudolf Amann." Bremen : Staats- und Universitätsbibliothek Bremen, 2019. http://d-nb.info/1199003700/34.

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Brian-Jaisson, Florence. "Identification et caractérisation des exopolymères de biofilms de bactéries marines." Phd thesis, Toulon, 2014. http://tel.archives-ouvertes.fr/tel-01058255.

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Dans l'environnement marin, les surfaces artificielles sont rapidement colonisées par des bactéries qui s'organisent en communautés appelées biofilms, s'entourant d'une matrice de substances polymériques extracellulaires (EPS). La formation d'un biofilm est une étape critique du processus nommé biofouling, c'est-à-dire l'accumulation de micro- et de macro-organismes sur une surface immergée, pouvant conduire à des conséquences néfastes dans le secteur marin. Dans cette étude, il s'agit d'identifier des souches bactériennes isolées de supports immergés en Mer Méditerranée et de les caractériser phénotypiquement par diverses approches. Leur capacité à former un biofilm in vitro a été évaluée dans différentes conditions avec une attention particulière portée sur leurs capacités à produire une matrice polymérique abondante riche en polysaccharides; l'objectif étant d'isoler des exopolysaccharides originaux à activité antifouling. Treize souches ont ainsi fait l'objet d'analyses phylogénétiques et d'une caractérisation phénotypique. Sept genres et douze espèces différentes ont été identifiés au sein desquelles deux isolats peuvent être affiliés à une nouvelle espèce, nommée Persicivirga mediterranea. Ce genre n'a jamais été décrit en Mer Méditerranée jusqu'à présent. L'extraction des EPS de chaque souche cultivée en biofilm a permis de déterminer leur composition générale en glucides, protéines, acides nucléiques et lipides. Une souche, Pseudoalteromonas ulvae TC14, se distingue par sa capacité à produire des exopolysaccharides en quantité importante. Il s'agit essentiellement de polymères du glucose dont les analyses chromatographiques et spectroscopiques ont révélé la diversité de taille (Mw ~ 1-4000 kDa), de charge (neutre ou anionique) et de fonction associée (lactate ou acétate). Les fractions d'EPS enrichies en polysaccharides inhibent la formation de biofilm par d'autres souches marines. Ces derniers sont également synthétisés par les bactéries en culture planctonique mais en proportions très différentes.

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Quinderé, Ana Luíza Gomes. "Propriedades na nocicepção e na inflamação de uma fração polissacarídica sulfatada da alga marinha Acanthophora muscoides." reponame:Repositório Institucional da UFC, 2013. http://www.repositorio.ufc.br/handle/riufc/4265.

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QUINDERÉ, A. L. G. Propriedades na nocicepção e na inflamação de uma fração polissacarídica sulfatada da alga marinha Acanthophora muscoides. 2011. 81 f. Dissertação (Mestrado em Bioquímica) Centro de Ciências, Universidade Federal do Ceará, 2011.
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Herein, a sulfated polysaccharidic fraction obtained from the marine alga Acanthophora muscoides (AmII) was evaluated using models of nociception and inflammation. The systemic toxicity of the total sulfated polysaccharides was also assessed. The antinociceptive properties were assayed using the writhing test induced by acetic acid, the formalin and the hot plate test. Swiss mice were treated with AmII (1, 3 or 9 mg/kg; i.v.) 30 min prior to either receiving an injection of 0.8% acetic acid or 1% formalin or prior to a thermal stimulus. AmII reduced the number of acetic acid-induced writhes and licking time in the second phase of the formalin test, but it did not alter the response latency in the hot plate test. The anti-inflammatory properties were assayed using the carrageenan-induced neutrophil migration into the peritoneal cavity and carrageenan- or dextran-induced paw edema models. Wistar rats were treated with AmII (1, 3 or 9 mg/kg; s.c.) 60 min prior to inflammatory stimuli. AmII reduced significantly the neutrophil migration into the peritoneal cavity. In the carrageenan-induced paw edema, AmII did not reduce the edema formation or the neutrophil migration, as assessed by the determination of myeloperoxidase levels in the paw tissue. However, AmII reduced dextran-induced paw edema during the first interval analysed. Furthermore, when AmII (500 μg) was injected (s.c.) into the paw, to verify a possible edematogenic effect, no edema was observed. Additionally, when mice were treated with the total sulfated polysaccharides from A. muscoides (20 mg/kg; i.p.) for 14 days, no consistent signs of systemic damage were observed, as revealed by body weight, liver, kidney, heart, spleen, thymus and lymph node wet weight and by biochemical, hematological and histopathological analyses. In conclusion, AmII has antinociceptive and anti-inflammatory properties and represents a potencial therapeutic agent warranting future studies.
No presente trabalho, uma fração polissacarídica sulfatada obtida da alga marinha Acanthophora muscoides (AmII) foi avaliada através de modelos de nocicepção e inflamação. A toxicidade sistêmica dos polissacarídeos sulfatados totais também foi analisada. A atividade antinociceptiva foi avaliada através dos ensaios de contorções abdominais induzidas por ácido acético, teste da formalina e da placa quente. Camundongos Swiss machos foram tratados com AmII (1, 3 ou 9 mg/kg; i.v.) 30 min antes de receber injeção de ácido acético 0,8% ou formalina 1% ou antes da exposição a um estímulo térmico. AmII reduziu significativamente o número de contorções abdominais induzidas por ácido acético e o tempo lambedura da pata na segunda fase do teste da formalina. No teste da placa quente, AmII não prolongou o tempo de reação dos animais. A atividade antiinflamatória foi avaliada através do ensaio de migração de células através da cavidade peritoneal induzida por carragenana (700 μg/ cavidade) e dos ensaios de edema de pata induzidos por carragenana (500 μg/pata) ou por dextrano (400 μg/pata). Ratos Wistar foram tratados com AmII (1, 3 ou 9 mg/kg; s.c.) 60 min antes do estímulo inflamatório. AmII reduziu significativamente a migração de neutrófilos através da cavidade peritoneal. No ensaio do edema de pata induzido por carragenana, AmII não reduziu a formação do edema e a migração neutrofílica, analisada através da determinação dos níveis teciduais de mieloperoxidase. Entretanto, AmII inibiu o edema de pata induzido por dextrano no primeiro intervalo analisado. Adicionalmente, quando AmII (500 μg) foi injetada (s.c.) na pata, para verificar um possível efeito edematogênico, não foi observado edema. No ensaio de toxicidade subcrônica, camundongos foram tratados diariamente durante 14 dias com os polissacarídeos sulfatados totais de A. muscoides (20 mg/kg; i.p.). Sinais consistentes de dano sistêmico não foram observados, conforme revelado pela avaliação do peso corporal e dos órgãos fígado, rim, coração, baço, timo, e linfonodo e das análises bioquímicas, hematológicas e histopatológicas. Como conclusão, a fração AmII possui propriedades antinociceptiva e antiinflamatória e representa um potecial agente terapêutico, justificando estudos futuros.

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Mann, Alexander J. [Verfasser], Frank Oliver [Akademischer Betreuer] Glöckner, Matthias [Akademischer Betreuer] Ullrich, Rudolf I. [Akademischer Betreuer] Amann, and Hanno [Akademischer Betreuer] Teeling. "Bioinformatic analyses of genomes, metagenomes and expression data of polysaccharide-degrading marine microbes / Alexander J. Mann. Betreuer: Frank Oliver Glöckner. Gutachter: Frank Oliver Glöckner ; Matthias Ullrich ; Rudolf I. Amann ; Hanno Teeling." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2013. http://d-nb.info/1087285046/34.

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Silva, Inês Maria Vaz. "In vitro hypocholesterolemic potential of marine polysaccharides." Master's thesis, 2020. http://hdl.handle.net/10773/28962.

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The prevalence of high cholesterol levels in the blood of the population translates in a mortality and morbidity index with high human and economic costs, being highly important to find new strategies to mitigate this problem. One way to reduce cholesterol levels in blood is to diminish its bioaccessibility, this is, decrease the amount that is emulsified in the intestinal lumen with the help of bile salts and thus available to be absorbed. In this work marine origin polysaccharides with different structural characteristics were explored, evaluating its hypocholesterolemic potential in an in vitro simplified intestinal model, as well as possible mechanisms of action. From brown algae Saccharina latissima, two types of polysaccharides were fractioned and structurally characterized, the laminarans (neutral) and fucose-containing sulphated polysaccharides (negatively charged). Chitosan (a positively charged polysaccharide) was also studied, which is a polysaccharide obtained from the deacetylation of chitin from crustaceous shells. The obtained results showed that the low molecular weight chitosan was the most promising polysaccharide, followed by the commercial fucoidan, in the reduction of cholesterol’s bioaccessibility, promoted by the sequestration of bile salts, whereas the other polysaccharides did not show a significant effect. To understand if other mechanisms of action were involved in the hypocholesterolemic effect of the marine origin polysaccharides, the viscosities of the most effective polysaccharides in reduction of cholesterol solubility were evaluated. In the concentration ranges studied, chitosan revealed higher viscosity compared to the commercial fucoidan. However, the diffusion coefficient evaluated by DOSY, which compared the solution in the presence and absence of chitosan, did not show significant alterations at the concentration used. This indicate that chitosan does not affect significatively the diffusion of bile salts micelles with cholesterol in the intestinal lumen, discarding this mechanism. Zeta-potential allowed to verify that at the physiologic pH used in the in vitro cholesterol solubility assays, the chitosan had positive charge, reinforcing the possibility of negatively charged bile salts sequestration by electrostatic interaction, corroborated by NMR quantification. Despite the negative character of fucoidan due to the sulphates groups and uronic acids, it has also capacity to sequestrate bile salts, contrary to what was observed with the laminarans (neutral), highlighting the possibility of hydrophobic interactions between bile salts and polysaccharides, depending on their structural nature. The present work allowed to identify that chitosan and fucoidans as potential to be used as hypocholesterolemic agents, detailing the possible mechanisms of action which can be useful for the design of functional foods with properties in reduction of cholesterol absorption that can have high impact in the society, namely in health and economy.
A prevalência de elevados níveis de colesterol no sangue da população traduz-se num índice de mortalidade e morbilidade com elevados custos humanos e económicos, sendo muito importante encontrar novas estratégias para mitigar este problema. Uma forma de diminuir os níveis de colesterol no sangue é diminuir a sua bioacessibilidade, ou seja, diminuir a quantidade que é emulsificada no lúmen intestinal com o auxílio de ácidos biliares e, portanto, disponível a ser absorvida. No presente trabalho, polissacarídeos de origem marinha com diferentes características estruturais foram estudados quanto ao seu efeito hipocolesterolémico, assim como possíveis mecanismos de ação, num sistema modelo intestinal in vitro simplificado. Da alga castanha Saccharina latissima foram fracionados e caracterizados estruturalmente dois tipos de polissacarídeos, as laminaranas (neutras) e os polissacarídeos sulfatados contendo fucose (carregados negativamente). Adicionalmente, estudou–se a quitosana (um polissacarídeo carregado positivamente), obtida por desacetilação da quitina, que normalmente é obtida a partir de cascas de crustáceos. Os resultados obtidos mostraram que a quitosana de baixo peso molecular foi o polissacarídeo mais promissor, seguido da fucoidana, na redução da bioacessibilidade de colesterol promovida pela sequestração de ácidos biliares, sendo que os restantes polissacarídeos não demonstraram um efeito significativo. Por forma a entender se outros mecanismos de ação estariam envolvidos no efeito hipocolesterolémico dos polissacarídeos de origem marinha, avaliou-se a viscosidade dos polissacarídeos mais efetivos na diminuição da solubilidade de colesterol, verificando-se que a quitosana apresentou a maior viscosidade em comparação com a fucoidana comercial nos regimes de concentração estudados. Contudo, o coeficiente de difusão obtido por DOSY, comparando a solução na presença e ausência de quitosana não mostrou alterações significativas à concentração usada, sendo indicativo que este polissacarídeo não afeta significativamente a difusão das micelas do ácido biliar com colesterol no lúmen intestinal, descartando este mecanismo. O potencial zeta permitiu verificar que ao pH fisiológico, usado nos ensaios de solubilidade de colesterol in vitro, a quitosana possuía carga positiva, reforçando a possibilidade de sequestração de ácidos biliares carregados negativamente por interação electroestática, corroborado por quantificação por RMN. A fucoidana apesar do seu carácter negativo conferido pelos grupos sulfatos e ácidos urónicos também mostrou sequestrar ácidos biliares, contrariamente ao observado com as laminaranas (neutras), realçando a possibilidade de interações hidrofóbicas entre os ácidos biliares e os polissacarídeos, dependendo da sua natureza estrutural. O presente trabalho identifica alguns polissacarídeos de origem marinha, nomeadamente a quitosana e as fucoidanas, com potencial para serem usados como agentes hipocolesterolémicos, detalhando possíveis mecanismos de ação que poderão ser úteis no design de alimentos funcionais com propriedades na redução de absorção de colesterol e consequentemente poderão ter elevado impacto na sociedade, nomeadamente na saúde e economia.
Mestrado em Bioquímica

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Johny, Archana. "Optosensors based on membranes built of marine polysaccharides." Dissertação, 2020. https://hdl.handle.net/10216/132015.

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Johny, Archana. "Optosensors based on membranes built of marine polysaccharides." Master's thesis, 2020. https://hdl.handle.net/10216/132015.

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"Antiviral and antitumor activities of polysaccharides from seaweeds." 2004. http://library.cuhk.edu.hk/record=b6073734.

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Wang Hui.
"December 2004."
Thesis (Ph.D.)--Chinese University of Hong Kong, 2004.
Includes bibliographical references (p. 256-280)
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Mode of access: World Wide Web.
Abstracts in English and Chinese.

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Lin, Ping-Ting, and 林娉婷. "Production of polysaccharides by a marine diatom using semi-continuous system." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/r4mkcd.

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碩士
國立中興大學
生物科技學研究所
106
Diatoms are one of the most important sources of biomass in the ocean, accounting for about 40% of marine primary production. Diatoms also contribute up to 20% of global CO2 fixation in the biosphere. In order to analyze the diatom polysaccharide production, we produce cell mass and total polysaccharides using a semi-continuous system for large-scale cultivation in this study. NCHU MYW AQ4 collected from marine waters at Kenting, Taiwan were identified as Halamphora sp., according to the morphological analysis and alignment of their 18S ribosomal DNA sequences (rDNA) with the corresponding 18S rDNA sequences of the known diatoms in NCBI database In standing culture, polysaccharides of AQ4 in 5f medium were more than that of AQ4 produced in f/2 medium. So, 5f medium or 10 f medium was selected for a long-term culture of AQ4 and analysis of polysaccharide production. When pH exceeded 9 in a long-term culture of AQ4 using an 8 L spinner flask with 5f medium, there would be obvious clustering. When pH decreased to a value between 8.5 and 9, AQ4 aggregation significantly disappeared and aparted evenly in 8 L spinner flask. At this time, AQ4 cell mass production reached about 0.5747 g/L. When the nutrient concentration was raised to 10f medium, the cell mass of AQ4 could reach a value of 0.7758 g/L. It was found that polysaccharides began to accumulate after 9 days of batch. The average intracellular and extracellular polysaccharides were 13.9401 mg/g and the average productivity of polysaccharides was 0.7187 mg/L/Day. In order to reach a higher cell mass and polysaccharide production, a semi-continuous system with a cycle of three days was investigated. The experiment was divided into four sets. Set 1 was 3 days to collect 2 L. Set 2 was 3 days to collect 3 L. Set 3 was 3 days to collect 1 L. Set 4 was 3 days to collect 1 L and added 20 mL 0.1 M Na2CO3. Set 1 is the highest cell mass productivity of set 1 – 3 and reaches a cell mass productivity of 0.15 g/L/Day. With an addition of carbon source (Na2CO3), cell mass and polysaccharides productivity could reach 0.20 g/L/Day and 6.64 mg/L/Day, respectively. Carbon source was the important factor affecting the productivity. Compared with the standing culture, the cell mass of set 4 was 13 fold than which for those obtained in a standing culture. The productivity of polysaccharide was 99.6 fold than which for standing culture. This study improves the productivity of cell mass for analysis of diatom metabolites and increases the productivity of polysaccharides for activity assays and structural identification.

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