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1
Hur, Jae-Seoun. "Effects of air pollution on Azolla-Anabaena symbiosis." Thesis, Lancaster University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359764.
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Clark, D. R. "Some aspects of DNA synthesis in Anabaena 2C." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383453.
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Arnold, Matthias. "Molekulargenetische Charakterisierung von Untereinheiten des Cytochrom-b6f-Komplexes von Cyanobakterien der Gattung Anabaena." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963645994.
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Moslavac, Suncana. "Outer membrane proteins of Anabaena sp. strain PCC 7120." Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-72771.
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Vargas, Sarah Regina. "Produção de hidrogênio por Chlamydomonas spp. e Anabaena spp." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-21032017-100636/.
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O uso intensificado de combustíveis fósseis como fonte de energia, vê-se a necessidade do desenvolvimento de novas tecnologias, principalmente as renováveis, como o hidrogênio, que possui vantagens por ser elemento abundante no universo, ser renovável e não poluente. A utilização de microalgas e cianobactérias é uma alternativa para a produção de biohidrogênio a partir da quebra da água e de compostos orgânicos. De acordo com isso, nesta pesquisa foram testados diversos fatores físico-químicos e nutricionais nas condições de cultivo de cepas de Chlamydomonas spp. e Anabaena spp. Para tanto, cepas selecionadas foram cultivadas em duas fases experimentais, a primeira aeróbia e a segunda anaeróbia, para proporcionar produção de hidrogênio por biofotólise direta anaeróbia, via hidrogenase, sob privação de enxofre para a clorofícea, e de nitrogênio para a cianobactéria, estimulando para esta também a produção por biofotólise indireta, via nitrogenase. A cepa com melhor produtividade de hidrogênio, de cada gênero, foi selecionada para a etapa de otimização das fases experimentais de cultivo. Durante os ensaios foram realizadas análises de produção máxima, velocidade de produção, volume e produtividade de hidrogênio, além de análises de concentração de biomassa, físico-químicas, bioquímicas e geração de subprodutos. O método utilizado foi eficiente para produção de hidrogênio e ficou comprovada a diferença de produção de hidrogênio entre diferentes cepas. Anabaena sp. obteve produtividade média de hidrogênio quatro vezes maior, aproximadamente de 76,8 µmol.L-1.h-1, comparada a C. reinhardtii, com média de 18,6 µmol.L-1.h-1.The intensifying use of fossil fuels as energy source, one sees the need to develop new technologies, especially renewable, such as hydrogen. This has advantages because hydrogen is an abundant element in the universe, be renewable and non-polluting. The use of microalgae and cyanobacteria is an alternative for the production of bio-hydrogen of breaking water and organic compounds. Accordingly, in this study were tested several physic-chemical factors and nutrition in growing conditions of Chlamydomonas spp. and Anabaena spp. strains. For this purpose, strains selected were cultured in two experimental phases, first aerobic and second anaerobic, to hydrogen production by direct biofotolise anaerobic, via hydrogenase, under sulfur deprived to chlorofycea, and nitrogen to cyanobacterium, for this also to production by indirect biofotolise, via nitrogenase. The strain with highest productivity of hydrogen, of each gender, was selected for the optimization of the experimental stages of cultivation. During the tests were analyzes of maximum production, velocity, volume and productivity of hydrogen, and analysis of biomass concentration, physic-chemical, biochemical and generation of by-products. The method used was efficient for the production of hydrogen and was different between strains. Anabaena sp. obtained average yield four times highest, approximately 76.8 µmol. L-1.h-1compared to C. reinhardtii, averaging 18.6 µmol. L-1.h-1.
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Gerphagnon, Mélanie. "Ecologie des chytrides parasites de la cyanobactérie Anabaena macrospora." Thesis, Clermont-Ferrand 2, 2013. http://www.theses.fr/2013CLF22385/document.
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En raison des forçages anthropiques exercés sur les écosystèmes aquatiques et des effets des changements globaux présents et à venir, on s’attend à une augmentation de la fréquence et de l’intensité des proliférations cyanobactériennes lacustres. Une meilleure connaissance des facteurs biotiques, et notamment du parasitisme, impliqués dans le control des dynamiques cyanobactériennes semble essentielle. Il est désormais établi que les Chytridiomycota (chytrides) constituent les principaux pathogènes fongiques du phytoplancton. Ainsi, les travaux de recherche menés au cours de cette thèse ont eu pour objectif d’étudier le parasitisme fongique associé aux efflorescences cyanobactériennes, et plus précisément l’écologie des chytrides parasites de la cyanobactérie Anabaena macrospora, espèce filamenteuse présentant des proliférations massives et récurrentes dans le lac d’Aydat (France). Par la mise en place d’un schéma d’échantillonnage temporel et spatial à haute fréquence et prenant en compte deux années consécutives (2010 et 2011), nous avons pu (i) étudier les cycles de vie des deux espèces de parasites fongiques associées à A. macrospora, (ii) évaluer l’impact de ces parasites sur la dynamique de la population cyanobactérienne, et (iii) caractériser des facteurs contrôlant la dynamique des systèmes hôtes-parasites d’intérêt. De plus, (iv) afin de mettre en exergue les relations étroites existantes entre l’hôte et la production fongique associée, nous avons mis au point des protocoles méthodologiques permettant une analyse microscopique fine de l’hôte, des sporanges et de leur contenu en zoospores (fécondité des chytrides). Les résultats acquis mettent en évidence la coexistence de deux espèces de chytrides, Rhizosiphon crassum et R. akinetum, associées à A. macrospora. La reconstruction des cycles de vie par analyse d’images prises à partir d’échantillons naturels nous a permis de montrer que les deux chytrides présentaient une durée de leur cycle de vie similaire, et estimée à environ 3j. pour R. crassum. Cependant, ces deux espèces se différencient d’un point de vue fonctionnel en parasitant des types cellulaires distincts : R. crassum influence directement la biomasse active en parasitant les cellules végétatives, alors que R. akinetum parasite les cellules de résistances (akinètes) de A. macrospora. Cette dernière espèce peut donc avoir un impact sur le recrutement, la structure génétique et la variabilité interannuelle de la population hôte. Par ailleurs, outre leur impact direct, nous montrons que l’action des chytrides parasites peut aboutir à une fragmentation mécanique des filaments de A. macrospora, augmentant potentiellement la perte de biomasse cyanobactérienne par broutage. De plus, nous avons pu mettre en évidence que la production zoosporique des chytrides dépendait des ressources nutritives disponibles tant d’un point vue quantitatif (taille de l’hôte) que qualitatif (groupe phytoplanctonique parasité, métabolisme de l’hôte...). La réduction de la biomasse active de cyanobactéries, la fragmentation mécanique, ainsi que la production de zoospores dont la qualité nutritive pour le zooplancton a été démontrée, établissent les chytrides comme lien trophique entre les proliférations cyanobactériennes filamenteuses « inedible », considérée comme impasses trophiques, et les niveaux trophiques supérieurs. Enfin, l’ensemble des résultats acquis montre l’intérêt de prendre en compte, désormais, le rôle fonctionnel des champignons microscopiques parasites, notamment comme agents régulateurs direct et indirect du développement phytoplanctonique. Cette prise en compte permettrait, sans aucun doute, d’améliorer les modèles de transferts de matière et d’énergie qui transitent dans les écosystèmes aquatiques, dans le contexte général d’optimiser la gestion des plans d’eauFace to both the important anthropogenic input in nutrients and the global change, numerous authors predict that the cyanobacterial blooms will increase in relative abundance in aquatic ecosystems. An exhaustive knowledge of the driving biotic factors of the cyanobacterial dynamic is essential. In lakes, the most common fungal parasites of phytoplankton belong to the phylum Chytridyomycota (i.e. chytrids). The aim of the thesis was to investigate the fungal parasitism associated to the cyanobacterial blooms, particularly the ecology of chytrids parasitizing the filamentous cyanobacterial species Anabaena macrospora, in Lake Aydat (France). During two successive years (2010-2011), investigations on (i) the chytrid cycle of life of two chytrid species parasitizing A. macrospora, (ii) the impact of the fungal parasitism on the cyanobacterial bloom dynamic and (iii) driving factors of the host-parasite pairings dynamics have been led during two spatio-temporal surveys using high resolution sampling strategies. Moreover (iv) a double staining method based on a combination of CFW and SYTOX green for counting, identifying, and investigating the fecundity of phytoplankton fungal parasites and the putative relationships established between hosts and their fungal parasites has been developed. Results underlined the coexistence of two chytrids, Rhizosiphon crassum and R. akinetum, which have similar life cycles but differed in their infective regimes depending on the cellular niches offered by their host. R. crassum infected both vegetative cells and akinetes while R. akinetum infected only akinetes. A reconstruction of the developmental stages suggested that the life cycle of R.crassum was completed in about 3 days. By infecting akinetes, R. akinetum could reduce or modify the genetic structure of the cyanobacterial bloom of the following year. Furthermore, chytrids may reduce the length of filaments of Anabaena macrospora significantly by ‘‘mechanistic fragmentation’’ following infection. All these results suggest that chytrid parasitism is one of the driving factors involved in the decline of cyanobacterial blooms, by direct mortality of parasitized cells and indirectly by the mechanistic fragmentation, which could weaken the resistance of A. macrospora to grazing. Moreover, we underlined that the production of zoospore depends on the nutritional host quantity (host size) and quality (host phytoplanktonic group, host metabolism...). The decrease of the cyanobacterial active biomass, mechanistic fragmentation, and production of zoospores which exhibit a high nutritional quality for the zooplankton, established the chytrids as a real link between the inedible filamentous cyanobacteria, considered as trophic dead ends, and the higher trophic levels. Overall, we consider that the acquisition of our data places the chytrid parasitism as an important driving factor of the phytoplankton dynamic, allowing the inclusion of fungi and their main function (parasitism) in the energy and matter fluxes in the pelagic ecosystems
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Jackson, Gardner H. "Biotransformation of 2,4,6-trinitrotoluene (TNT) by the cyanobacterium anabaena spiroides." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/20862.
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Bancroft, I. "An analysis of some cyanophages which infect Anabaena PCC 7120." Thesis, Lancaster University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379568.
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Li, Lih-Ann. "Molecular and biochemical studies of rubisco activation in Anabaena species /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487859879938986.
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Aldea, Maria Ramona. "Identification of novel regulatory mechanisms controlling heterocyst development in Anabaena Sp. strain PCC 7120." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2996.
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Bagatini, Inessa Lacativa. "Associação de bactérias à cápsula de Anabaena spiroides (Cyanobacteria) em cultura." Universidade Federal de São Carlos, 2008. https://repositorio.ufscar.br/handle/ufscar/1936.
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The cyanobacterium Anabaena spiroides, a cosmopolitan species occurring in eutrophic environments as in Barra Bonita reservoir, is covered by a thick polysaccharide capsule that provides a microenvironment for association of bacterial communities. The aims of this study were: to identify bacteria attached to A. spiroides capsule to evaluate interspecific relationships among bacteria communities and A. spiroides, considering bacteria selectivity and succession dynamics of attached bacteria; as well as the effect of bacterial inoculum (1.2 µm filtered water from Barra Bonita reservoir) on cyanobacterial growth. For this purpose, density, production, biomass and diversity of bacteria attached to cyanobacteria capsules and free-living bacteria were determined in two replicate cultures of A. spiroides inoculated with bacteria from Barra Bonita reservoir. The diversity was verified by the number of bands obtained through separation of PCR amplification products of 16S rDNA from free-living and attached bacterial communities using Denaturing Gradient Gel Electrophoresis (DGGE). Bacteria attached to the capsule were identified by sequencing the fragment of 16S rDNA. A set of cultures were performed to evaluate cyanobacterial growth as affected by Barra Bonita filtered water. A. spiroides cultures without Barra Bonita inoculum were used as control. The results showed that bacterial density, biomass and total production were higher for free-living bacteria, but no significant difference was obtained between attached and free-living bacteria regarding production per cell. The diversity was lower for the attached bacteria than free-living ones. Three strains of attached bacteria present in A. spiroides inoculum, identified as one Acidobacteria and two Alphaproteobacteria, remained up to the beginning of exponential growth phase. At the senescence phase these bacteria were replaced by four strains identified as one Deltaproteobacteria, one Betaproteobacteria, one Bacilli (Firmicutes) and one unidentified strain. This research demonstrated that there were selectivity and succession in the bacterial community attached to A. spiroides, and that the addition of the filtered water from Barra Bonita inoculum accelerates the death of cyanobacterium cultures
A cianobactéria Anabaena spiroides, cosmopolita em ambientes eutrofizados como o reservatório de Barra Bonita, é recoberta por uma espessa cápsula de polissacarídeo que fornece um microambiente para o crescimento de uma comunidade bacteriana particular. Os objetivos deste trabalho foram: identificar as bactérias associadas à cápsula de A. spiroides para detectar possíveis relações interespecíficas entre estas e a cianobactéria, considerando a seletividade e a dinâmica de sucessão das bactérias associadas; verificar o efeito da adição do inóculo bacteriano (água do reservatório de Barra Bonita filtrada em 1,2 µm) no crescimento da cianobactéria. Para tanto, a densidade, produção, biomassa e a diversidade das bactérias livres e aderidas à cianobactéria, assim como a identificação das bactérias aderidas foram determinadas em duas culturas de A. spiroides inoculadas com bactérias do reservatório de Barra Bonita. A diversidade foi verificada pelo número de bandas obtidas em Denaturing Gradient Gel Electrophoresis (DGGE) após a amplificação do 16S rDNA das comunidades bacterianas das frações livre e aderida e as bactérias aderidas à cápsula foram identificadas pelo seqüenciamento do fragmento do 16S rDNA. Em outro experimento, o crescimento da cianobactéria foi verificado pela concentração de clorofila a e carbono orgânico total após a adição da água de Barra Bonita (filtrada em 1,2µm) em quatro culturas experimentais de A. spiroides. Os controles consistiram em culturas de A. spiroides sem o inóculo de Barra Bonita. Os resultados mostraram que a densidade, biomassa e produção total das bactérias foram sempre maiores para as bactérias livres, no entanto, com relação à produção por célula, não houve diferença significativa entre aderidas e livres. Este estudo também mostrou que a diversidade das bactérias aderidas foi menor do que das livres e que três linhagens de bactérias aderidas que estavam presentes no inóculo de A. spiroides, permaneceram até o início da fase de crescimento exponencial. Essas bactérias foram identificadas como uma Acidobacteria e duas Alphaproteobacteria. Na fase de senescência essas bactérias foram substituídas por outras quatro linhagens: uma Deltaproteobacteria, uma Betaproteobacteria e uma Bacilli (Firmicutes) e uma linhagem não identificada. No segundo experimento as concentrações de clorofila e carbono foram menores nas culturas adicionadas do inóculo bacteriano do que nos controles. O presente estudo demonstrou que houve seleção e sucessão das bactérias aderidas a A. spiroides e que a adição da água de Barra Bonita acelera a morte das culturas da cianobactéria
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Muir, Gillian Morag. "The gene encoding the glyphosate-tolerant EPSP synthase from Anabaena variabilis." Thesis, University of Glasgow, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320276.
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Bowness, Peter William. "Intracellular zinc and copper : sequestration and trafficking in Anabaena PCC 7120." Thesis, University of Newcastle Upon Tyne, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413939.
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Agathangelou, Damianos. "Anabaena Sensory Rhodopsin : effect of mutations on the ultrafast photo-isomerization dynamics." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAE001/document.
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ASR, est une protéine photo réceptrice qui lie la base protonée de la rétine de Schiff dans deux conformations de l'état fondamental. La protéine particulière consiste en un système modèle dans lequel I'effet de l'environnement protéique sur la dynamique d'isomérisation des deux isomères peut être étudié. Dans cette thèse, une étude approfondie sur les protéines mutées ponctuellement est présentée, où la variable est l'environnement protéique. Les résultats montrent des différences significatives entre les durées de vie des états excités des deux isomères et les durées de vie plus courtes ou plus longues commentées en termes de mélange électronique Sl/S2. En complément, le développement expérimental d'un spectromètre à absorption transitoire (T.A) et d'un dispositif de spectroscopie électronique bidimensionnelle (2DES) fonctionnant respectivement dans les domaines spectral NIR et UV-Vis. Avec cette configuration, deux impulsions colinéaires à verrouillage de phase d'une durée inférieure à 10fs sont générées, où. la précision interférométrique sur le contrôle du retard entre les deux impulsions de pompe permet d'effectuer des mesures 2DESASR, is a photoreceptor protein that binds the protonated Schiff base of retinal in two ground state conformations. The particular protein consists a model system where the effect of the protein environment on the isomerization dynamics of the two isomers can be investigated. In this thesis an extended study on point mutated proteins is presented where the variable is the protein environment. The results show significant differences between the two isomers excited state lifetimes with the shorter or longer lifetimes commented in terms of Sl/S2 electronic mixing. Supplementary, the experimental development of a Transient absorption spectrometer (T.A) and a Two-dimensional electronic spectroscopy setup (2DES) operating in the NIR and UV-Vis spectral range respectively are described. The 2DES spectrometer is based on translating wedges made out of birefringent material producing two collinear phase-locked pulses with sub-I Ofs duration. The interferometric precision on controlling the delay between the two pump pulses allows to perform 2DES measurements on systems absorbing in the 360-430 nm range allowing to resolve the excitation process spectrally
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Andrade, Carolina Ferreira. "Otimização do cultivo de cianobactérias para a produção de hidrogênio." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-18072017-101318/.
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O hidrogênio (H2) produzido a partir de microrganismos fotossintetizantes (microalgas e cianobactérias) é considerado um vetor energético sustentável do ponto de vista ambiental. Quando comparado a outras formas de produção são encontradas limitações técnicas e econômicas principalmente pela geração de pequenos volumes de gás e pela inexistência de um ciclo de vida completo que assegure a produção contínua de H2 por esses organismos. Nesse sentido, o presente projeto teve por propósito avaliar a capacidade de produção de H2, sob condições mixotróficas, em três estirpes de cianobactérias: Anabaena sp. UTEX 1448, Anabaena sp. PCC7120 (selvagem) e Anabaena sp. PCC 7120 ΔhypF (mutante). O primeiro capítulo tratou da otimização de biomassa da estirpe UTEX 1448, utilizando meio de cultura BG-11 (Rippka, 1979), em condições controladas de pH (10,2), temperatura (32 ºC), radiação (30 µmol.m-2.s-1), com cinco diferentes substratos orgânicos (ácido lático, glicerol, glicose, frutose e sacarose), em três concentrações de carbono (0,20; 0,52 e 0,84 gC.L-1). No segundo capítulo, investigou-se a produção de H2, pelas enzimas hidrogenase bidirecional, de assimilação e nitrogenase, com medições in vivo, a partir do uso do eletrodo de H2 (Hansatech, Ltd) e análises de clorofila a, proteínas (Western Immunoblotting) e géis de poliacrilamida desnaturantes. Os ensaios de H2 foram realizados para as três estirpes, em triplicata, com réplicas biológicas nos dias 0h, 24h, 48h, 72h e 7 dias, após passagem das culturas de condições não fixadoras de nitrogênio para condições fixadoras de H2, considerando a condição otimizada encontrada no Capítulo 1. Utilizou-se BG-11 para aumento da densidade celular em níveis que viabilizassem a realização dos ensaios e BG-110 (sem nitrato) para estímulo à diferenciação celular em heterocistos, estrutura importante por conter a enzima nitrogenase, diretamente relacionada à geração de H2. A fonte de carbono orgânico frutose a 0,84 gC.L-1 foi a condição otimizada encontrada, com produtividade de biomassa de 190 ± 18 mg.L-1.dia-1 (Anova, Tukey, p < 0,05). A estirpe mutante não cresceu nas condições otimizadas do cultivo e consequentemente não foi possível quantificar a geração de H2. Em fase clara, aos 7 dias, a maior produtividade de H2 foi de 0,50 ± 0,38 µmolH2.mg clorofila a-1.h-1 para a cepa PCC 7120 (selvagem) e na fase escura obteve-se produtividade média de H2 de 0,147 ± 0,00 µmolH2.mg clorofila a-1.h-1, ao dia 0 (0h) para a estirpe UTEX 1448.Hydrogen (H2) produced from photosynthetic microorganisms (microalgae and cyanobacteria) is considered an environmentally sustainable energy vector. When compared to other production ways, some technical and economic limitations are found mainly because of the small amount of gas generated and also due the lack of a complete life cycle that assures the constant generation of hydrogen by these organisms. Regarding to this, the following study intended to evaluate the capacity of hydrogen production under mixotrophic conditions in three cyanobacteria strains: Anabaena sp. UTEX 1448, Anabaena sp. PCC7120 (wild type) and Anabaena sp. PCC 7120 ΔhypF (mutant). The first chapter refers to the optimization of the biomass of the UTEX1448 strain, using BG-11 as a mean of culture (Rippka, 1979) under controlled conditions of pH (10,2), radiation (30 µmol.m-2.s-1), temperature (32ºC), with no photoperiod, five different organic substrates (lactic acid, glycerol, glucose, fructose and sucrose) in three different carbon concentrations (0.20, 0.52 and 0.84 gC.L-1). The second chapter investigated the hydrogen production by the bidirectional hydrogenases enzymes, by uptake and nitrogenase, with in vivo measurements using the hydrogen electrode (Hansatech, Ltd), chlorophyll a and proteins analyses (Western Immunoblotting and SDS-Polyacrylamide gels). The H2 assays were performed for the three strains, in triplicate, with biological replicates on days 0h, 24h, 48h, 72h and 7 days, considering the optimized condition found in Chapter 1. BG-11 medium was used to increase cell density at levels that would be viable to perform the tests and BG-110 (without nitrate) to stimulate cell differentiation in heterocysts, an important structure that contains the nitrogenase enzyme, directly related to H2 generation. The source of organic carbon fructose at 0.84 gC.L-1 was the optimized condition found, with biomass productivity of 190 ± 18 mg.L-1.day-1 (ANOVA, Tukey, p < 0.05). The mutant strain did not grow under optimized culture conditions and consequently it was not possible to quantify H2 generation. In the light phase, at 7 days, the highest yield of hydrogen was 0.50 ± 0.38 µmolH2.mg chlorophyll a-1.h-1 for the strain PCC 7120 (wild) and in the dark phase yielded average productivity of hydrogen from 0.147 ± 0 µmolH2.mg chlorophyll a-1.h-1, at day 0 (0h) for strain UTEX 1448.
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Green, Damian William, and n/a. "The phytoplankton community in Chaffey Dam, focusing on the influence of light on the growth and photophysiology of the cyanobacterium anabaena circinalis." University of Canberra. Science &Design, 2001. http://erl.canberra.edu.au./public/adt-AUC20060712.155533.
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This research investigated the factors influencing the structure of the phytoplanktori
community in Chaffey Dam, which is located in sub-tropical Australia. In particular, the
research aimed to determine the influence of light at time scales ranging from seconds to
seasons, on the growth and photophysiology of the cyanobacterium Anabaena circinalis.
On a large scale, field monitoring programs between 1987 and 1997 indicated that the
phytoplankton community of Chaffey Dam was dominated by colonial or relatively large
phytoplankton that move either with the aid of flagella or can be positively buoyant. Diatoms
contributed only a minor component, which may be the result of the reservoir being stratified
for much of the year. Several of the dominant taxa bloomed in each of the seasons during the
eleven year period, with some blooms lasting >9 months, indicating that environmental
variability between seasons can be low. In contrast to other studies, A. circinalis was more
likely to grow and bloom during the cooler months (March-October). A two-year intensive
monitoring program (1995-1997) identified a seasonal progression that was similar in both
years. Chlorophytes occurred in spring, Ceratium in mid summer, a relatively clear period in
February, A. circinalis in March and cryptomonads in winter.
On a smaller scale, short-term (2-3 day) in-situ and laboratory enclosure experiments found
that the light and nutrient requirements of the dominant taxa varied. In comparison to most
other phytoplankton, A. circinalis cells disappeared at very rapid rates when supplied
irradiances <10 (umol photons m-2 s-1. Over several days of darkness, the filaments broke
apart and the cell numbers declined. The experiments also showed that at certain times, field
populations of A. circinalis were subject to high losses at all irradiances.
Laboratory studies investigating the influence of inter- and intra-daily changes in light
availability showed that the growth rate of A. circinalis was not affected by the frequency of
daytime light:dark cycles, indicating that the rate of water mixing will not have major
influence on its growth if the total daily light dose is maintained. It was also found that
A. circinalis cultures did not accumulate large reserves of energy in the form of carbohydrate,
other than that required for one night. This strategy may enable the colonies to have a high
level of buoyancy each morning so that they float quickly to the surface waters and obtain
sufficient light each day to minimise losses. However, this strategy limits the ability of
A. circinalis to grow and maintain vital cell processes during extended periods of low
irradiances and may be a factor causing them to be susceptible to cell breakdown.
Weekly measurements of algal growth rates in Chaffey Dam identified two factors that may
have acted singly or simultaneously to influence the development of A. circinalis blooms
during 1996 and 1997. The blooms developed during a 4-6 week period when the mean
irradiance in the surface mixed layer (SML) was sufficient to prevent high losses. Secondly,
the blooms developed when soluble phosphorus in the epilimnion was relatively high but
soluble nitrogen was low. This may have favoured A. circinalis, which has the potential to fix
atmospheric nitrogen. The decline of A. circinalis blooms was correlated with a deepening of
the SML and a reduction of the mean daytime irradiance within the SML. Their decline did
not appear to be related to nutrient limitation or to changes in zooplankton concentrations.
This research also developed a physiological technique for tracking daily changes in the mean
daytime irradiance of A. circinalis and for estimating cell growth rate. This method is based
on chlorophyll-a fluorescence quenching analysis of the state transition mechanism, which
regulates light availability between the photosystems. The mean daytime irradiance of
A. circinalis showed a strong relationship with the degree of non-photochemical quenching
(qn), whereas the relative change to the maximum fluorescence showed a strong relationship
with cell growth. It is anticipated that this method will provide a useful research tool for
determining the relative importance of light and other factors on the net growth of
A. circinalis and other cyanobacteria.
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Berg, Holger. "Untersuchungen zu Funktion und Struktur der Cyanophycin-Synthetase von Anabaena variabilis ATCC 29413." Doctoral thesis, [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968889018.
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Kanacher, Tobias. "Die Adenylatcyclase CyaB1 aus Anabaena sp. PCC 7120 ist ein cAMP-sensitives Protein." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=967492041.
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El, Semary Nermin Adel Hussein. "Anabaena and associated bacteria : molecular approaches to studying microbial community structure and taxonomy." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420889.
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Burkhart, Brian M. "Structure of Recombinant Flavodoxin from Cyanobacteria Anabaena 7120 determined at 1.40 Å Resolution /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487858417984339.
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Zhang, Lichen. "L'étude des mécanismes de l'échange intercellulaire chez la cyanobactérie Anabaena sp. PCC 7120." Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX22108.
Full textAbstract:
La communication intercellulaire se produit non seulement chez les eucaryotes, mais aussi chez certaines bactéries. Un tel exemple est la cyanobactérie filamenteuse Anabaena sp. PCC 7120, capable de former des hétérocystes suite à une carence en azote combiné. Un filament d'Anabaena est coordonné comme une unité multicellulaire; comment les cellules communiquent-elles le long de chaque filament et comment échangent-elles des ressources nutritionnelles demeurent des mécanismes encore mal élucidés. Des études récentes ont démontré que des molécules de petites tailles peuvent être échangées entre les cytoplasmes à travers des jonctions intercellulaires. De plus, le périplasme semble être continu le long de chaque filament, avec une membrane extérieure commune pour toutes les cellules. Toutefois, il n’est pas déterminé si le "périplasme continu" peut servir comme une route alternative pour les échanges moléculaires le long des filaments.Dans cette étude, la propriété du périplasme chez Anabaena a été évaluée par le suivi du mouvement de protéines fluorescentes (GFP ou iLOV) en utilisant des techniques microscopiques. Les protéines fluorescentes ont été exportées vers l'espace périplasmique, soit d'un hétérocyste soit d’une cellule végétative. Nous avons pu montrer que ces protéines fluorescentes restent dans le périplasme de la cellule d’origine, et que la GFP peut diffuser librement, mais seulement dans le périplasme d'un hétérocyste ou d’une cellule végétative. Ainsi, bien que le périplasme semble être continu le long du filament, une barrière intercellulaire semble exister pour empêcher la libre diffusion des protéines à la taille de ~27 kDa (GFP) ou ~13 kDa (iLOV). La couche de peptidoglycane pourrait constituer cette barrière et nous estimons que la limite pour la diffusion à travers cette barrière se situe entre 0.53 et 13 kDa.En parallèle, les voies métaboliques des cellules végétatives et des hétérocystes ont été comparées en utilisant une approche transcriptomique. L'expression différentielle des gènes impliqués dans le métabolisme nous permet d’appréhender la nature des métabolites pouvant être échangées entres ces deux types cellulairesCell-cell communication occurs not only in eukaryotes but also in bacteria. One such example is the filamentous cyanobacterium Anabaena sp. PCC 7120, which is able to differentiate a specialized cell type named heterocyst upon nitrogen deprivation. A filament of Anabaena is coordinated as a multicellular unity; how the cells along each filament communicate and exchange resources are not yet fully understood. Recent studies demonstrated that small molecules can be rapidly exchanged from cytoplasm to cytoplasm through intercellular junctions. In addition, the periplasm appears to be continuous along each filament, with a shared outer membrane for all cells. However, whether the ‘continuous periplasm’ serves as an alternative route for molecular exchanges along the filament remains unknown. In this study, the property of periplasm in Anabaena was assessed by monitoring the movement of fluorescent proteins (GFP or iLOV) using microscopic techniques. Fluorescent proteins were exported to the periplasmic space of either a heterocyst or a vegetative cell and their diffusion was tested. We found that both GFP and iLOV remains in the producing cells, and at least GFP could diffuse freely in the periplasm of a heterocyst or a vegetative cell but failed to cross cell borders. Thus although periplasm appears to be continuous along the filament, barriers exist to prevent free diffusion of proteins up to the size of ~27 kDa (GFP) or ~13 kDa (iLOV). One candidate as diffusion barrier in the periplasm may be the peptidoglycan and we estimate the limit for diffusion of the barrier in the range between 0.53 to 13 kDa. In parallel, the biosynthetic pathways operating in vegetative cells and heterocysts were compared using oligonucleotide microarray. Differential expression of the genes involved in amino acids metabolism give clues as to which nitrogen-containing compounds might serve as the transfer vehicle in cell-cell exchanges
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Lyon, Jacob Daniel. "Exploring the mechanism of bioelectrocatalytic production of ammonia with whole cell Anabaena variabilis." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5962.
Full textAbstract:
Ammonia is an important compound to many industries around the world. Most of the fertilizers used by crop growers have ammonia as an essential ingredient. It can also be useful as a fuel source, offering greater energy density per unit than hydrogen and greater safety. Currently, the predominant method for producing ammonia on an industrial scale is by the Haber-Bosch process. This process uses steam evolution of methane to provide H2 gas, which is then combined with N2 gas over an iron catalyst to form NH3. This process requires large amounts of energy as well as high temperatures and pressures.
Here, an alternative method for ammonia production is explored. With Anabaena Variabilis, a photosynthetic cyanobacteria, on a carbon electrode, ammonia can be generated at ambient temperatures and pressures at little energy cost, a few tenths of a volt. A bioelectrocatalytic device has been constructed by immobilizing whole cell a. variabilis in a Nafion film modified with a trimethyl octadecyl ammonium bromide (TMODA) salt at an electrode surface [3]. The polymer modified electrode provides the driving force and reductive microenvironment to facilitate production of NH3 by nitrogenase and nitrate/nitrite reductase enzymes present in a. variabilis. Ammonia production by cyanobacteria were increased from basal levels of 2.8 ± 0.4 µM produced over a two week period, to 22 ± 8 µM produced in 20 minutes under mild voltage perturbation, roughly 104% increase in rate.
Control of ammonia producing structures (nitrogenase in heterocystic cells or nitrate/nitrite reductase in vegetative cells) can be accomplished by growing the algae with and without fixed sources of nitrogen in the growth media. With the addition of various nitrogen-containing gases to the electrolyte solution during cyclic voltammetry, there is evidence that biofilms containing a mixture of cell types increases ammonia production above controls when the nitrogen is present as NO2-, NO, or N2O. Chronoamperometric perturbation studies show increased ammonia production at near +600 mV and -300 mV vs SCE. In cyclic voltammetric studies, nitrate/nitrite reductase in vegetative-only biofilms responds favorably to positive voltage ranges, while isolated heterocyst biofilms containing nitrogenase can be effectively targeted with the application of a negative voltage profile.
References:
[1] Johna Leddy and Timothy M. Pashkewitz, Ammonia Production Using Bioelectrocatalytic Devices, US Patent Application 20140011252
[2] Timothy M. Paschkewitz, Ammonia Production at Ambient Temperature and Pressure: An Electrochemical and Biological Approach, Ph.D., University of Iowa, 2012.
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Roy, Partha Pratim [Verfasser], and Tiago [Akademischer Betreuer] Buckup. "Femtosecond Coherent Vibrational Dynamics of Anabaena Sensory Rhodopsin / Partha Pratim Roy ; Betreuer: Tiago Buckup." Heidelberg : Universitätsbibliothek Heidelberg, 2019. http://d-nb.info/1180326660/34.
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Sakr, Samer. "Régulation de la différenciation par le cycle cellulaire chez la cyanobactérie Anabaena PCC 7120." Aix-Marseille 2, 2006. http://www.theses.fr/2006AIX22024.
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La cyanobactérie Anabaena PCC 7120 est utilisée comme organisme modèle pour l'étude des processus de différenciation cellulaire chez les procaryotes. En réponse à une carence en azote combiné dans le milieu, cette cyanobactérie filamenteuse différencie en 24 heures des cellules spécialisées dans la fixation de l'azote atmosphérique, les hétérocystes. Un échange de métabolites entres les cellules végétatives et les hétérocystes assurent la croissance des filaments dans des conditions de carence en azote combiné. Les cellules végétatives qui réalisent la photosynthèse approvisionnent les hétérocystes en composés carbonés et les hétérocystes, assimilant l'azote moléculaire, fournissent aux cellules végétatives des composés azotés. Les hétérocystes représentent environ 10% des cellules sur chaque filament et se répartissent selon un profil semi-régulier. L'objectif de la thèse est de comprendre le choix des cellules à se différencier en hétérocystes au moment de l'induction. Nous postulons que le cycle cellulaire constitue un signal pour permettre à une cellule à se différencier. Au cours de mon travail de thèse, utilisant des approches de biologie cellulaire et de biologie moléculaire, j'ai analysé divers paramètres du cycle cellulaire, étudiant la synthèse de l'ADN, et la division cellulaire, des étapes clefs du cycle cellulaire. J'ai également mis en évidence un lien étroit entre le cycle cellulaire et la différenciation chez cet organisme. L'inhibition de la progression du cycle cellulaire supprime la différenciation. Le cycle cellulaire constituerait une nouvelle voie de signalisation indépendante du 2-oxoglutarate qui a été montré comme signal initiateur de la différenciation des hétérocystes. L'interaction entre FtsZ, une protéine de la division cellulaire, et HetN, une protéine nécessaire pour le maintien du profil des hétérocystes, pourrait représenter la connexion entre ces deux processus physiologiques. FtsZ, modérément surexprimée serait favorable pour la différenciation et HetN inhiberait la différenciation en perturbant la division cellulaire. Nous proposons que les cellules appartenant à une phase particulière du cycle cellulaire seront compétentes pour percevoir la carence en azote combiné et initier la différenciationThe filamentous cyanobacterium Anabaena PCC 7120 is a model organism for studies on cell differentiation. This strain, under combined nitrogen starvation, can differentiate heterocysts, cells specialized in nitrogen fixation. Heterocysts are distributed according to a semi-regular pattern along each filament, representing 10% of all cells. Heterocysts provide fixed nitrogen to vegetative cells and receive from the latter carbohydrates. In this study, we investigated if the initiation of heterocyst differentiation may be coupled to a favourable position in cell cycle. Using multi-disciplinary approaches, we analysed key steps of the bacterial cell cycle such as DNA synthesis and cell division. Inhibition of cell division arrests the progression of cell cycle and suppresses heterocyst differentiation. Cell cycle could regulate the early steps of heterocyst differentiation independent of the 2-oxoglutarate signal, a trigger of heterocyst formation. The interaction between FtsZ, a protein known to initiate cell division, and HetN that plays an important role in the maintenance of the heterocyst pattern, may represent the molecular connection between cell cycle and heterocyst differentiation. A moderate overexpression of FtsZ favours heterocyst differentiation. Overexpression of HetN inhibits heterocyst differentiation probably by preventing FtsZ polymerisation. We propose that cells in a critical stage of the cell cycle are competent to initiate differentiation
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Jones, Karen Lorraine. "Analysis of ferredoxin and flavodoxin in Anabaena and Trichodesmium using fast protein liquid chromatography." PDXScholar, 1988. https://pdxscholar.library.pdx.edu/open_access_etds/3812.
Full textAbstract:
Iron is an essential nutrient for growth of photosynthetic microorganisms such as cyanobacteria and algae. Iron is required for proteins involved in the important processes of carbon and nitrogen assimilation. Low concentrations of iron in cultures or natural waters can lead to iron limitation which affects many aspects of algal metabolism. In natural waters, iron limitation can have effects on the patterns and rates of primary productivity.
The cellular content of certain proteins can be affected by media iron concentrations. Methods have been used that assay components of the cell as an indirect measure of iron nutritional status. For example, spectroscopy can be performed to determine the cellular concentration of iron-containing proteins involved in photosynthesis. Organisms grown in media that imitate natural conditions, or organisms collected from their natural habitat are usually dilute. Methods that assay iron nutritional status such as spectroscopy and column chromatography require large sample sizes which are difficult to obtain from natural samples. In addition, methods that utilize techniques such as immunology or radioactive labelling are complex and time-consuming. These considerations led to the necessity of developing a technique that would be simple, rapid and effective on dilute samples. The method developed here utilized fast protein liquid chromatography (FPLC), which fulfilled these requirements. A complete analysis could be done within two to three hours with minimal sample treatment. The FPLC was simple to operate and was effective on a sample containing less than 100 μg of protein.
Some photosynthetic organisms, when iron-depleted, can produce the flavin-containing protein flavodoxin (Flv). This protein substitutes for the iron-containing protein ferredoxin (Fd) in Fd-dependent reactions such as the light-induced reduction of NADP. The FPLC technique identified and quantified, in relative terms, Fd and Flv in the cell. Optical spectroscopy was used to verify FPLC retention time assignments. The results illustrated how the FPLC could be used to observe the changes in relative Fd and Flv content as a function of media iron concentration in cultures of the cyanobacterium Anabaena grown in the laboratory. It was found that Fd content decreased and Flv content increased with decreasing media iron concentration. In addition, samples of the cyanobacterium Trichodesmium collected from the ocean near Barbados were analyzed using FPLC to assay relative Fd and Flv content. By analogy with Anabaena, Fd and Flv retention times were identified. Using this technique conclusions could be drawn regarding the changing iron nutritional status of Trichodesmium in its natural habitat .
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Padovan, Armando V. "The production of geosmin by Anabaena circinalis (Rabenhorst), and its measurement by sensory analysis /." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09MS/09msp124.pdf.
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Oliveira, Ádria Caloto de. "Toxicidade de elementos-traço para consumidores primários na presença de exopolissacarídeos produzidos por organismos fitoplanctônicos (Chlorophyceae e Cianophyceae)." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-06122007-142654/.
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O impacto causado pelo aumento da quantidade de substâncias químicas descartadas no meio ambiente está presente na maioria dos ecossistemas. Poluentes industriais contendo metais são frequentemente transportados para a água, o solo e o ar, podendo-se acumular nas cadeias tróficas e apresentar toxicidade para a biota. Em ambientes aquáticos, a biodisponibilidade e destino dessas substâncias xenobióticas podem ser influenciadas por vários fatores, entre eles a matéria orgânica dissolvida e outros compostos quelantes, os quais tem capacidade de aprisionar ou liberar íons para o ambiente. Os exopolissacarídeos, substâncias excretadas pelo fitoplâncton, podem interagir com diversas substâncias, interferindo na toxicidade dos compostos para os organismos ou comunidades biológicas aquáticas e, conseqüentemente, subestimando o verdadeiro valor tóxico das substâncias. Este trabalho foi conduzido para determinar a influência dos exopolissacarídeos da Clorofícea Pseudokirchniriella subcapitata, e da Cianofícea Anabaena spiroides na toxicidade dos elementos traço cádmio e cromo em Daphnia similis (Cladocera). Os metais foram escolhidos pela afinidade por quelantes orgânicos. Foram realizados testes ecotoxicológicos agudos para verificar a sensibilidade do cladócero Daphnia similis em diferentes concentrações dos metais cádmio (cloreto de cádmio) e cromo (dicromato de potássio), adicionando algas e exopolissacarídeos. Nos testes com os exopolissacarídeos foram utilizadas diferentes frações (excretado total, 10000D). Para obtenção das frações de exopolissacarídeos foram realizadas filtrações tangenciais em cartucho oco de celulose com bomba peristáltica. Nos testes com a adição das algas foram usados números conhecidos de células obtidas do concentrado de algas. Observou-se redução da toxicidade de 20 a 30% nos testes com a adição de excretado total, e reduções menores para as frações 10KD para as clorofícea e cianofícea. Com os resultados deste trabalho, foi possível avaliar a capacidade dessas substâncias em quelar e indisponibilizar compostos tóxicos e avaliar a toxicidade das substâncias quando testadas nos organismos planctônicos.Chemical substances have been exerting increasing impact on ecosystems. Industrial pollutants containing metals frequently reach water bodies, soil, and air, wherein they may accumulate on the trophic chain, resulting in toxicity to the biota. In aquatic environments, the bioavailability and the destination of these xenobiotics are influence by several factors, such as the amount of solved organic matter and other chelating compounds, since these substances can either bind or liberate ions to the environment. Exopolysaccharides, in particular, are excreted by phytoplankton and, once in water, can interact with several substances altering the toxicity of compounds to aquatic organisms and biological communities. As a consequence, the real toxic potential of these xenobiotics is underestimated. The aim of this work was to determine the influence of the exopolysaccharides produced by the Chloroficeae Pseudokirchniriella subcapitata and by the Cyanophiceae Anabaena spiroides on the toxicity of the trace-elements cadmium and chromo over the primary consumer Daphnia similis. These metals were chosen due to their high affinity towards organic chelators. Tests for acute ecotoxicity were performed to verify the sensitivity of the Cladocera Daphnia similis exposed to different cadmium (cadmium chloride) and chromo (potassium dichromate) concentrations, with and without algae and/or exopolysaccharides. Three fractions of exopolysaccharides were tested (total excreted, < 1000D, and > 1000D), which were obtained by tangencial filtration through a cellulosis membrane using a peristaltical pump. On tests using algae, a fixed number of cells were obtained from an algae concentrate. The toxicity of Daphnia similis to the metals was 20-30% reduced when the total excreted from algae was added, while the reduction in toxicity was lower to the fraction than 10KD. The results demonstrated that exopolysaccharides chelate toxic compounds rendering them unavailable for exerting their effects on planktonic organisms.
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Pengelly, Jasper John Lobl Biotechnology & Biomolecular Sciences Faculty of Science UNSW. "Molecular characterisation of membrane transporters associated with saxitoxin biosynthesis in cyanobacteria." Publisher:University of New South Wales. Biotechnology & Biomolecular Sciences, 2008. http://handle.unsw.edu.au/1959.4/41429.
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The release of the neurotoxic alkaloid saxitoxin by cyanobacterial cells was previously thought to occur primarily after cell lysis, yet recent evidence also suggests active toxin export by membrane transporters. Transporter proteins associated with STX biosynthesis in Cylindrospermopsis raciborskii T3 (sxtF and sxtM) and Anabaena circinalis 131C (naDt) were predicted to be involved in the export of STX from cyanobacterial cells. The main aim of this project was to characterise the transporters associated with STX biosynthesis, by investigation of their genetic prevalence, functional substrates and specific regulation. An sxtM homologue was discovered in A. circinalis 131C, as part of an sxt cluster, and found to be uniquely associated with STX-producing strains. Bioinformatic and phylogenetic analysis showed that the translated sxt transporters clustered with the NorM prokaryotic MATE sub-family and membrane topology analysis predicted 12 membrane-spanning regions. To characterise the functional substrates of the putative STX-transporters, they were heterologously expressed in the antibiotic-sensitive E. coli strain KAM32. Expression of the sxt MATES complemented host sensitivity to the cationic fluroquinolone antibiotics, ciprofloxacin and ofloxacin. Disruption of gene homologues of naDt and the sxt MATE genes in Synechocystis sp. PCC6803 yielded mutant strains with increased sensitivity to the toxic organic cations, methyl viologen and acriflavine. Transcription of the putative STX transporters, and the putative STX biosynthesis gene sxtA, was studied in C. raciborskii T3 and A. circinalis 131C under alkali and Na+ stress. Alkali stress (pH 9) decreased total STX levels in A. circinalis 131C and was correlated with a down-regulation of the putative transport and biosynthetic genes. In C. raciborskii T3, alkali stress promoted higher extracellular but lower intracellular STX levels, which also correlated with large increases in transcription of the putative STX transport genes.
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Bui, Lan Ahn. "Optimisation de la production de biomasse et d’ammonium extracellulaire par des cyanobactéries diazotrophes cultivées en photo-bioréacteurs." Nantes, 2013. http://www.theses.fr/2013NANT2100.
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Les propriétés diazotrophiques de cyanobactéries hétérocytées sont étudiées depuis plus de deux décennies pour des applications agricoles. Elles sont actuellement réexaminées comme source d'azote pour la production d'algofuels. L'objectif de ce travail était d'identifier les paramètres cinétiques déterminants pour la production de biomasse et d'ammonium extracellulaire par culture en photo-bioréacteurs d'une cyanobactérie hétérocytée. Différents caractères ont été associés à la production de biomasse et d'ammonium, tels que le taux d'hétérocytes, le profil d'acides gras et les vitesses spécifiques d'excrétion d'ammonium dans des cultures Anabaena variabilis PCC 7937. Ce phénotypage partiel a permis de caractériser une souche, A. Variabilis PCC 7937-C9, obtenue par double mutagenèse associée à une inhibition de la glutamine synthétase. Les cinétiques de production de la souche mutante ont été comparées à celles de la souche sauvage en mode chémostat en relation avec le taux de dilution et les teneurs en carbone inorganique. L'étude menée en régime stationnaire a montré que les paramètres des transferts gaz-liquide sont déterminants. Les différences entre les valeurs de productivités volumétriques et spécifiques en ammonium extracellulaire obtenues en photobioréacteurs à trichomes encapsulés dans des billes d'alginate de calcium et celles obtenues en cultures de trichomes libres de la souche mutante ont été analysées en fonction de l'état de colonisation des gels d'immobilisation et des transferts de gaz. Cette étude a permis d'acquérir des données expérimentales sur les conditions de bioproduction d'ammonium pouvant être utilisé pour la culture de microalguesBesides potential applications in the agriculture field as natural nitrogen fertilizer, Nr fixing cyanobacteria have recently gained some attentions for new applications linked to the potential production of biologically active molecules or small molecules such as hydrogen or ammonium for algafuels. The aim of this research was to investigate kinetic and yield parameters for biomass and extracellular ammonium production by heterocytous cyanobacteria cultures in photobioreactors. Preliminary data dealed with phenotypic traits of Anabaena variabilis PCC 7937 included heterocyts proportion, fatty acids composition and specific rate of ammonium excretion characteristics linked to biomass production and ammonium release. A mutant strain, A. Variabilis PCC 7937-C9 was obtained by double random mutagenesis treatment with ethyl methane-sulfonate, followed by selection in batch cultures with increasing concentrations of a glutamine synthetase inhibitor, methionine sulfoximine. The wild-type and the mutant strains were compared using a kinetic analysis of biomass production and ammonium excretion in continuous cultures as a function of the dilution rate and the inorganic carbon supply. Experimental data confirmed that molecular nitrogen transfer to culture medium is a limiting factor for cell growth and ammonium excretion in diazotrophic free-cell cultures. This limitation seems to explain the low specific ammonium excretion rates obtained in Ca-alginate immobilized cells of A. Variabilis PCC 7937-C9 in photobioreactors. These experimental data have highlighted some bioproduction conditions of ammonium, which could be used as N-source for microalgae production
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Honda, Ricardo Yukio. "Caracterização morfológica e molecular de cianobactérias do gênero Anabaena isoladas de corpos d\'água brasileiros." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/11/11138/tde-24062009-085724/.
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Com o advento dos estudos moleculares evolutivos baseados nas sequências dos genes de RNAr 16S em cianobactérias, a taxonomia de Anabaena (Cyanobacteria) tem sido amplamente discutida e uma revisão deste gênero faz-se necessária. Os problemas variam desde o nível genérico, tal como o grupo Anabaena Aphanizomenon, até níveis de diferenciação de linhagens (morfoespécies). Estudos moleculares de linhagens de Anabaena isoladas de ecossistemas brasileiros são inexistentes. A fim de se explorar a diversidade, filogenia e diversificação evolutiva de Anabaena isoladas de ambientes brasileiros, estudos fenotípicos e genotípicos foram realizados no presente estudo. Um total de 43 isolados foram obtidos de corpos d´água do Estado de São Paulo (Reservatórios Billings, Santo Grande, Rio Piracicaba e Lago da ESALQ/USP (Engenharia) e do Estado do Ceará (Lagoa do Povoado Nova Aurora e Rio Camarão). As espécies de Anabaena isoladas foram identificadas como A. aphanizomenoides Forti, A. circinalis Rabenhorst ex Bornet et Flahault, A. crassa (Lemmermann) Komárková-Legnerová et Cronberg, A. cf. fallax Komárek et Komárková-Legnerová e A. planctonica Brunnthaler. Os meios de cultura usados no isolamento das cianobactérias foram AA/4, ASM-1 e BGN, este último também nas variantes com 50% de NaNO3 (BG50) e sem nitrato (BGS), com ou sem adição de vitamina B12. O meio ASM-1 não promoveu o crescimento de Anabaena. As espécies A. circinalis e A. crassa não cresceram no meio de culturaBGN com 17,65 mM de NaNO3, apresentando crescimento no meio BG50. A adição de vitamina B12 favoreceu o crescimento de A. circinalis. Os caracteres morfológicos analisados para 23 isolados foram o comprimento (compr) e diâmetro (diam) da célula vegetativa (V), heterócito (HT), acineto (AC), espira (ES), razões (R) comprimento/diâmetro para V, HT e AC e razão diâmetro/comprimento para ES (RES). O diâmetro da bainha (diamBA) foi também avaliado. As análises de componentes principais (ACP) confirmaram que a espira é uma característica importante para separar as morfoespécies A. circinalis, A.crassa e A. cf. fallax. RV e RHT foram diacríticos para diferenciação de A. cf. fallax. O comprimento do acineto (comprAC) foi importante para diferenciar A. aphanizomenoides de A. planctonica. A bainha diferenciou A. crassa das outras morfoespécies. As análises filogenéticas para o RNAr 16S mostraram os isolados brasileiros de A. circinalis, A. crassa, A. planctonica, A. aphanizomenoides e A. cf. fallax em agrupamentos separados, confirmando os resultados dos caracteres morfológicos. Com exceção da A. planctonica, as sequências de RNAr 16S dos isolados brasileiros não agruparam com linhagens relativas provenientes de outros países, indicando que elas são únicas. As análises filogenéticas dos genes RNAr 16S, rpoC1, rbcL, tufA concatenados corroboraram os resultados de filogenia do gene de RNAr 16S e as identificações morfológicas. A tentativa de obtenção de padrões moleculares para as espécies de Anabaena isoladas do Brasil foi feita utilizando a técnica de PCR-DGGE. Os fragmentos da região 359-781 do RNAr 16S apresentaram banda única para A. circinalis, enquanto que mais de uma banda foi verificado nas outras morfoespécies de Anabaena.The advent of molecular evolutionary studies based on 16S rRNA genes sequences of cyanobacteria, the taxonomy of Anabaena (Cyanobacteria) has been widely discussed and a revision of the genus is required. The problems range from the generic level, such as Anabaena Aphanizomenon group, to levels of strains differentiation (morphospecies). Molecular studies of Anabaena strains isolated from Brazilian ecosystems are lacking. In order to explore the diversity, phylogeny and evolutionary diversification of Anabaena strains isolated from Brazilian environments, phenotypic and genotypic studies were performed. A total of 43 Anabaena isolates were obtained from water bodies of Sao Paulo State (Billings reservoir, Santo Grande reservoir, Piracicaba river and Engenharia pond Esalq) and Ceara State (Povoado Nova Aurora pond and Camarao river). The isolated Anabaena species were identified as A. aphanizomenoides Forti, A. circinalis Rabenhorst ex Bornet et Flahault, A. crassa (Lemmermann) Komárková-Legnerová et Cronberg, A. cf. fallax Lomárek et Komárková-Legnerová and A. planctonica Brunnthaler. The culture media used for cyanobacterial isolation were AA/4, ASM-1 andBGN, the latter also in the variants with NaNO3 50% (BG50) and without nitrate (BGS), with and without addition of B12 vitamin. The ASM-1 medium did not promote the growth of Anabaena. The A. circinalis and A. crassa species had not grown inBGN culture medium with NaNO3 17.65 mM, showing growth in BG50 medium. The addition of B12 vitamin favored the growth of A. circinalis. The morphological characters analyzed for 23 isolates were the length (L) and diameter (D) of vegetative cell (V), heterocyte (HT), akinete (AK), coil (CO), L/D ratio (R) for V, HT and AK, and D/L ratio for CO (RCO). The sheath diameter (SD) was also evaluated. The principal component analysis (PCA) confirmed that the coil is an important feature to separate the morphospecies A. circinalis, A.crassa and A. cf. fallax. RV and RHT were diacritical for differentiation of A. cf. fallax. The akinete length (LAK) was important to differentiate A. aphanizomenoides from A. planctonica. The sheath differentiated A. crassa from other morphospecies. Phylogenetic analyses of 16S rRNA gene placed A. circinalis and A. crassa, A. planctonica, A. aphanizomenoides and A. cf. fallax Brazilian isolates in separated clades in agreement with morphological characters. With the exception of A. planctonica, the 16S rRNA sequences of the Brazilian isolates did not cluster with relative strains originated from other countries, indicating that they are unique. The phylogenetic analysis of concatenated genes16S rRNA, rpoC1, rbcL, tufA corroborated results of 16S rRNA phylogeny and morphological identifications. The attempt to obtain molecular standards for the Anabaena species isolated from Brazil was made using the PCR-DGGE technique. The fragments of the 359-781 region of 16S rRNA showed only one DNA band for A. circinalis, while more than one band was observed in other Anabaena morphospecies.
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LE, BAY-LE DOARE JOCELYNE. "L'Association symbiotique Azolla-Anabaena : effets de la salinité et importance d'un nouveau partenaire : Corynebacterium sp." Rennes 1, 1991. http://www.theses.fr/1991REN10118.
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Azolla est une fougere aquatique qui etablit une symbiose avec une cyanobacterie fixatrice d'azote: anabaena azollae. Nous avons mis en evidence la presence d'un autre partenaire dans la symbiose, une bacterie non chlorophyllienne et apparemment non fixatrice d'azote corynebacterium sp. Dans l'association, les plantes fournissent le carbone (saccharose), les cyanobacteries fournissent l'azote (ammoniaque) et les corynebacteries fourniraient un hormone de croissance vegetale. L'association est non halophile et sensible au stress salin. Sa culture sur milieu sale (nacl 0,15 m) conduit a l'entree massive d'ions sodium dans les tissus et a la perte simultanee d'eau et d'ions potassium. Parallelement, les activites enzymatiques du vegetal et des cyanobacteries sont ralenties, et, bien que c. Sp presente en culture pure une halophilie moyenne, la viabilite de l'association est reduite. Elle peut etre amelioree par l'incorporation de glycine betaine (gb) a 10 mm final au milieu. La gb n'est jamais trouvee parmi les solutes synthetises par l'association. Seules les corynebacteries semblent presenter la capacite de la synthetiser a partir de choline et de cataboliser la gb en glycine et serine qui sont ensuite rejetees. Ces acides amines peuvent alors etre repris par azolla et a. Azollae et c'est sous cette forme que l'association pourrait tirer profit de la gb et non par son accumulation comme osmoprotecteur
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Barbosa, Ana Teresa Perdigão. "Produção de Biohidrogénio pela cianobactéria Anabaena sp. PCC 7120 e mutantes: efeito do ciclo de luz (dia/noite) e da intensidade luminosa." Master's thesis, Faculdade de Ciências e Tecnologia, 2009. http://hdl.handle.net/10362/5094.
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Hodge, Sarah Anne. "The study of protein serine/threonine kinase mediated phosphorylation in the cyanobacterium Anabaena sp. strain PCC7120." Thesis, University of Warwick, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284030.
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Tremblay, Robin Lee. "Expression and characterisation of a gene encoding RbpD, an RNA-Binding protein in Anabaena sp. strain PCC 7120 /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0019/MQ54968.pdf.
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Chu, Ngoc Thuy. "Association symbiotique d'une algue bleue (Anabaena azollae Strasburger) et d'une fougère (Azolla filiculoides Lamarck) : étude écologique et physiologique." Paris 11, 1986. http://www.theses.fr/1986PA112170.
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Diogo, Elsa Maria dos Santos. "Utilização de Algas na produção de bioetanol." Master's thesis, Instituto Politécnico de Tomar, 2012. http://hdl.handle.net/10400.26/5849.
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Este trabalho, desenvolvido no contexto de estágio curricular nos laboratórios de Engenharia Química e Ambiente do Instituto Politécnico de Tomar, teve como principal objectivo estudar a potencialidade de produzir biomassa algal, de forma integrada no processo de tratamento de águas residuais através de zonas húmidas construídas. Neste âmbito, desenvolveram-se actividades predominantemente de foro experimental segundo três vertentes: a implementação ou validação de técnicas analíticas, tais como a determinação da concentração de nutrientes na fase aquosa, o teor de biomassa em termos secos e o teor de açúcares totais e redutores; o estudo da potencialidade de utilização de lixiviados, ricos em nutrientes, obtidos de argilas expandidas usadas como enchimento de zonas húmidas construídas, como meio de crescimento de micro e de macroalgas; a avaliação e tentativa de optimização do crescimento das microalgas e das macroalgas.
Escolheu-se a macroalga Cladophora aegagropila atendendo a estar referenciada pela sua capacidade de clarificação das águas. Estudou-se o crescimento da macroalga em substratos tradicionais, e na argila expandida sem qualquer tratamento, verificando-se uma aparente boa adequação das algas a este diferente substrato. Não existindo dados na literatura sobre o teor de açúcares ou amidos nesta alga, determinou-se por análise que o teor em açúcares totais é de 38,8%, dos quais 22,4% são açúcares redutores.
Foram também estudadas duas microalgas, Anabaena sp. e Spirogyra sp. Avaliou-se a cinética de crescimento em diferentes meios de crescimento, determinando-se a taxa específica de crescimento e o tempo de duplicação. A concentração máxima obtida foi de 0,21 g/L para a Anabaena sp., sendo de salientar que o meio líquido obtido por lixiviação da argila expandida comprovou ser apropriado para o crescimento das microalgas, apesar de conduzir a taxas específicas de crescimento inferiores. A utilização dos lixiviados pode representar uma redução de custos na produção de algas, e uma forma de regenerar os materiais de enchimento usados nas zonas húmidas construídas
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Pinzon-Gamez, Neissa M. "HETEROCYSTOUS N2-FIXING CYANOBACTERIA: MODELING OF CULTURE PROFILES, EFFECT OF RED LIGHT, AND CELL FLOCCULATION STUDY." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1145115095.
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Paschkewitz, Timothy Michael. "Ammonia Production at Ambient Temperature and Pressure: An Electrochemical and Biological Approach." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/4893.
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The majority of power generated worldwide is from combustion of fossil fuels. The sustainability and environmental impacts of this non renewable process are severe. Alternative fuels and power generation systems are needed, however, to cope with increasing energy demands. Ammonia shows promise for use in power generation, however it is costly to produce and very few methods of using it as a fuel are developed. To address the need for alternative methods of ammonia synthesis, this research designed and tested a bioelectrochemical device that generates NH3 through electrode induced enzyme catalysis. The ammonia generating device consists of an electrode modified with a polymer that contains whole cell Anabaena variabilis, a photosynthetic cyanobacterium. A. variabilis contains nitrogenase and nitrate/nitrite reductase, catalysts for the production of ammonia. In this system, the electrode supplies driving force and generates a reductive microenvironment near cells to facilitate enzymatic production of NH3 at ambient temperatures and pressures.
Farm animal wastes contain significant amounts of NO2- and NO3-, which can leech into groundwater sources and contaminate them. The system described here recycles NO2- and NO3- to NH4sup+ by the nitrate/nitrite reductase enzyme. Unlike nitrogen fixation by the nitrogenase enzyme whose substrate is atmospheric N2, the substrates for nitrate/nitrite reductase are NO2- and NO3-. The ammonia produced by this system shows great potential as a crop fertilizer.
While the substrates and enzymatic basis for ammonia production by nitrogenase and nitrate/nitrite reductase are very different, there is utility in the comparison of commercially produced ammonia by the Haber Bosch synthesis and by the bioelectrocatalytic device described here. In one day, the Haber Bosch process produces 1800 tons of NH3 at an energetic cost of $500/ton. Per ton of ammonia, the Haber Bosch process consumes 28 GJ of energy. The bioelectrocatalytic device produces 1 ton of NH3 for $10/ton, consuming only 0.04 GJ energy, which can be obtained by sunlight via installation of a photovoltaic device. Thus, the system presented here demonstrates ammonia production with significant impact to the economy.
NH3 production by the bioelectrocatalytic is dependent upon A. var. cell density and electrode polarization. The faradaic current response from cyclic voltammetry is linearly related to cell density and ammonia production. Without electrode polarization, immobilized A. var. do not produce ammonia above the basal level of 2.8 ± 0.4 ΜM. Ten minutes after cycled potential is applied across the electrode, average ammonia output increases to 22 ± 8 ΜM depending on the mediator and substrate chemicals present. Ammonia is produced by this system at 25 °℃ and 1 atm. The electrochemical basis for enhanced NH3 by immobilized cyanobacteria is complex with multiple levels of feedback.
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Kang, Wenli. "Kinetic study of ammonium/ammonia production by Anabaena variabilis cultures in relation with a continuous gas stripping." Thesis, Nantes, 2016. http://www.theses.fr/2016NANT4041/document.
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Certaines cyanobactéries photoautotrophes sont capables de fixer l’azote atmosphérique grâce à des cellules spécialisées, les hétérocytes. De plus, en aérobiose, comme ces cellules peuvent excréter de l’ammonium lorsque leurs activités glutamine synthétase sont partiellement inhibées. Elles sont considérées comme usines cellulaires potentielles pour une bioproduction d’engrais azoté. Nous utilisons une souche mutante de Anabaena variabilis PCC 7937-C9, cyanobactérie hétérocytée à taux de croissance élevé, pour étudier la capacité à produire de l’ammonium en photobioréacteurs. Les caractéristiques de croissance de cette souche ne différent pas significativement de celles de la souche sauvage, avec un taux de croissance spécifique maximal de 3.0 j–1 à 30°C. Nous montrons qu’une partie de l’azote excrété dans le milieu de culture est entrainé sous forme de NH3 par la phase gazeuse, expliquant ainsi des sous-estimations antérieures. Cette production dépend de la température, l’irradiance, le taux d’aération et la concentration en MSX. Des études cinétiques confirment que la production d’azote ammoniacal en phase liquide et en phase gazeuse est corrélée aux variations de pH. Une régulation pulsée de pH permet d’accroitre la production de NH3. Des cultures en chemostat confirment que les productions de NH3 gazeux sont maximales à pH 8.8. Une variation cyclique des teneurs en NH4 +/NH3 dissous semble réguler les teneurs en NH4 +/NH3 en dessous d’un seuil critique de 1.5 mmol L–1 via une consommation par les cellules végétatives. Ces caractéristiques physiologiques sont analysées pour une application potentielle à la fourniture d’azote à des cultures de microalgues oléagineusesSome photoautotrophic cyanobacteria species are able to fix dinitrogen thanks to specialized cells, the heterocyts. Moreover, these cells are known to secrete ammonia when the glutamine synthase activity is partially inhibited under aerobic conditions. They are considered as potential cell factories for fertilizer. The present study uses a mutant strain of Anabaena variabilis PCC 7937-C9, a fast-growing heterocytous cyanobacterium, to investigate the potential use of diazotrophic cyanobacteria in photobioreactors for ammonium production. The growth characteristics of this strain cultivated in chemostat cultures are not significantly different from those of the wild strain, with a maximal specific growth rate of 3.0 d–1 at 30°C. A part of the combined nitrogen excreted in the culture medium is shown to be stripped through the aeration of the cultures as NH3, indicating previous underestimation of NH4 +/NH3 excretion. This process is shown to be affected by parameters such as temperature, irradiance, gas flow rate and MSX concentrations. Kinetics study reveals that the dissolved NH4 +/NH3 as well as the gaseous NH3 productions are correlated to pH variations production; a pulse regulation of pH is used to increase the NH3 production. Chemostat cultures with pH regulation are used to confirm that maximal gaseous NH3 is produced at pH 8.8. A cyclic variation of dissolved NH4 +/NH3 seems to regulate the NH4 +/NH3 concentrations under a threshold level of 1.5 mmol L–1; uptake of NH4 + by vegetative cells seems to be involved. These physiological features are discussed in view of operative conditions for efficient nitrogen supply for production by oleaginous microalgae
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Crawford, Kathryn A. "The Effects of Nutrient Ratios and Forms on the Growth Of Microcystis aeruginosa and Anabaena flos-aquae." ScholarWorks @ UVM, 2008. http://scholarworks.uvm.edu/graddis/59.
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Cyanobacteria are ancient prokaryotic organisms capable of performing oxygenic photosynthesis. An increase in the temporal and spatial distribution of cyanobacteria blooms worldwide has drawn considerable research attention in recent decades because of the health risks cyanobacteria pose to humans and wildlife through the production of cyanotoxins, interference with recreation, and ecosystem changes. A variety of hypotheses have sought to explain the increasing frequency and severity of cyanobacteria blooms around the world, with the relationship between cyanobacteria abundance and eutrophication receiving considerable attention. While the impacts of phosphorus concentration on cyanobacteria success are relatively well-studied, less is known about how nutrient stoichiometry and nitrogen uptake kinetics of different species contribute to cyanobacteria dominance. The underlying mechanism for the impacts of nitrogen to phosphorus (N:P) ratio and nitrogen form on cyanobacteria involves internal cycling of nitrogen within lakes and aspects of cyanobacteria cell physiology. The primary objective of this study was to assess the impacts of N:P ratios and nitrogen form on the growth of Microcystis aeruginosa and Anabaena flos-aquae in both axenic cultures and natural phytoplankton assemblages from Missisquoi Bay, Lake Champlain. A second objective was to determine whether treatment condition affected the production of the cyanotoxin microcystin. A final objective was to document the presence of benthic ammonium in Missisquoi Bay and the vertical migration of cyanobacteria throughout the water column in the bay, to provide evidence in support of the underlying mechanisms that might provide advantages to cyanobacteria in the bay. In laboratory culture experiments with M. aeruginosa and A. flos-aquae alone and in a mixed community, N:P ratios were varied between 5, 15, 30 and 45:1, and nitrogen was supplied as both nitrate and ammonium at each ratio. Triplicate samples were preserved after one, three and six days for cell enumeration using the standard Ütermohl method. Differences in density between initial and later times were used as an estimate of growth. Microcystin concentration was measured with the ELISA method. Weekly field sampling was conducted in the summer of 2006 in Missisquoi Bay to measure benthic nitrogen concentrations. Nocturnal sampling at varied depths in the bay was used to explore the vertical migration of cyanobacteria throughout the water column. There were weak associations between ammonium-nitrogen and M. aeruginosa growth and nitrate-nitrogen and A. flos-aquae growth, while the effects of N:P ratio on growth was highly variable across time and treatment condition. Ammonium-nitrogen was documented in the benthic water of Missisquoi Bay throughout the growing season, and M. aeruginosa dominated the vertical migration of cyanobacteria throughout the water column. The lack of clear trends visible within the data from laboratory experiments can be in part attributed to high variability of cell density within treatment conditions and the limitations of the methodology used for cell enumeration. Taken together these data suggest that the distribution of nitrogen within an aquatic system and the ability of M. aeruginosa to vertically migrate may contribute to the M. aeruginosa dominance of the summer phytoplankton community.
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Prentice, Matthew James. "Temporal and spatial variations of cyanobacteria in Karori Reservoir, Wellington." The University of Waikato, 2008. http://hdl.handle.net/10289/2363.
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The Lower Karori Reservoir (LKR) is a small, monomictic lake of 2.34 ha situated in the Karori Wildlife Sanctuary (KWS), Wellington. Over the past decade cyanobacterial blooms have become a common occurrence in this water body. In 2005 Anabaena planktonica was detected for the first time in the LKR and this species now forms dense blooms during summer. These blooms are problematic as they reduce aesthetic appeal and have resulted in odour problems for visitors to this high profile wildlife sanctuary. The objectives of this study were to identify key physical, chemical and biological variables influencing phytoplankton dynamics in the LKR and to use ecological models to investigate plausible management options. The key parameters investigated, that may cause bloom formation were; summer stratification, high nutrient levels, and the food web effects of a large population of European perch (Perca fluviatilis). High resolution sampling was carried out every six hours over a 72 hour period during pre-bloom, bloom and post-bloom periods in 2006/7 to elucidate short term temporal and spatial variations in biological and physico-chemical parameters. Quantitative polymerase chain reaction (QPCR) was used to enumerate A. planktonica populations, allowing a large number of samples to be simultaneously evaluated. Algal densities were also estimated using conventional phytoplankton enumeration and chlorophyll a analysis. Water samples were collected for nutrient analysis at discrete depths and profiles were taken for temperature, dissolved oxygen and photosynthetic active radiation. Secchi depth and pH were also measured. Weekly or fortnightly phytoplankton and zooplankton samples and physical variables have been collected at LKR since September 2005 as part of an independent sampling program carried out by the KWS, Waikato University and Cawthron Institute. In this project the 2-year data set was used to assist with analysis of lake processes and for validation of the hydrodynamic-ecological model DYRESM-CAEDYM. Between 12 and 15 February, 2007, electric fishing was undertaken within the LKR. A total of 3,946 P. fluviatilis were removed and the effects on phytoplankton and zooplankton concentrations were investigated. To increase knowledge of the physiology of A. planktonica, laboratory experiments were undertaken using cultures subjected to a range of different light intensities and temperature regimes The phytoplankton assemblage of the LKR shows very distinct temporal variations. Summer stratification occurred in the LKR for ~4 months each summer. During these periods A. planktonica comprised up to 99.9% of the surface phytoplankton population. During isothermy chlorophytes, bacillariophytes and small flagellated dinophytes are co-dominant in the phytoplankton assemblage. The results of the QPCR showed distinct diurnal vertical movement of A. planktonica, with the highest cell concentrations occurring at 1900 hours at the surface. Ammonium (NH4-N) is the dominant species of inorganic nitrogen during periods of stratification, while nitrate (NO3-N) is generally dominant during times of isothermy. Phosphate concentrations at surface and depth remained at low levels throughout the sampling period. The large surface populations of A. planktonica, are probably responsible for the elevated total nitrogen concentrations in surface waters during stratified periods. There appeared to be some short term effects of the P. fluviatilis removal with an increase in large crustaceans (e.g., Daphnia sp.) and a reduction in A. planktonica densities observed in the months following the P. fluviatilis removal. Only a small proportion of the total P. fluviatilis population was removed and it is unlikely that the effects will be long-lasting without subsequent removal steps. However, it seems likely that P. fluviatilis is one of the factors contributing to cyanobacterial blooms and management of this fish species should be considered in future lake restoration plans. Growth experiments indicated A. planktonica grow over a wide range of light intensities and temperatures, although highest growth rates were generally associated with higher temperatures (25 C) and light intensities (60 - 140 μmol m-2 s-1). Ecological and hydrodynamic trends within the LKR over a two year period were simulated with adequate success using the model DYRESM-CAEDYM. Management scenarios simulated using DYRESM-CAEDYM suggest implementation of an artificial destratification system in the LKR may be the most practical and effective means of controlling A. planktonica blooms. The addition of an artificial aeration system emitting air at a rate of approximately 50 l-1 s-1 should result in an isothermal system. Without summer stratification some of the physiological features of A. planktonica (e.g., buoyancy regulation and nitrogen-fixation) that give it a competitive advantage over other phytoplankton species will be reduced.
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Brookes, Justin Dean. "The influence of nutrients and light on the metabolic activity and buyoancy of Microcystis aeruginosa and Anabaena circinalis /." Title page, contents and summary only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phb8711.pdf.
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Howell, Larry Daniel II. "Characterization of IphP from Nostoc commune UTEX 584 and a Dual Specificity Protein Phosphatase from Anabaena PCC 7120." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30344.
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Protein phosphorylation is utilized universally as a mechanism of signal transduction. However, the use of tyrosine phosphorylation by bacteria has been a matter of dispute. Conventional wisdom dictated that "prokaryotic phosphorylation" was typified by phosphorylation of histidine and aspartate residues of proteins, while "eukaryotic phosphorylation" was characterized by modification of serine, threonine, or tyrosine residues. Increasing numbers of reports have emerged challenging the traditional view of "prokaryotic" and "eukaryotic" phosphorlyation. One of the strongest links unifying prokaryotic and eukaryotic protein phosphorylation to date is IphP, a genomically-encoded dual-specificity protein phosphatase from the cyanobacterium Nostoc commune UTEX 584 bearing the active-site signature sequence of eukaryotic tyrosine-specific and dual-specificity protein phosphatases.
The catalytic properties and substrate specificity of IphP were examined in detail. The enzyme was able to discriminate among a variety of exogenous peptides and proteins. Kinetic studies revealed that IphP favors protein / peptide substrates over low molecular weight compounds.
Heparin effected IphP activity in a substrate-dependent manner. Enzyme activity toward casein (P-Ser) and MAP kinase (P-Thr/P-Tyr) was stimulated in the presence of the polyanion, whereas activity was inhibited by heparin toward other protein substrates. Both stimulation and inhibition by heparin were dose-dependent. The ability to stimulate IphP activity toward select substrates was attributed to the ability of heparin to recruit the enzyme and substrate to the same microenvironment.
To facilitate future genetic studies examining the role of tyrosine phosphorylation in cyanobacteria, we searched for evidence of protein tyrosine phosphorylation in Anabaena PCC 7120. In a collaborative effort with the laboratory of Dr. Potts, tyrosine phosphorylated proteins were identified in Anabaena utilizing several approaches, including comparative labelling with alpha- vs gamma-32P-ATP, phosphoamino acid analysis, and selective hydrolysis with a tyrosine specific protein phosphatase. Together, these data unequivocally demonstrate the presence of tyrosine-phosphorylated proteins in Anabaena PCC 7120.
Extracts of Anabaena PCC 7120 were examined for protein tyrosine phosphatase activity. An apparent PTP activity was detected, partially purified, and characterized. The protein phosphatase was ~38kDa by SDS-PAGE and sucrose density gradient centrifugation and displayed dual-specificity protein phosphatase (DSP) activity in vitro. The enzyme was localized to the periplasm and was thus assigned the title PAD, for Periplasmic Anabaena DSP. Periplasmic phosphoproteins of ~120 and 55 kDa that had been radiolabelled in vitro were dephosphorylated by partially purified PAD. PAD activity varied in vivo ~5-fold in a rhthymic, seemingly diurnal manner. Periplasmic proteins, including the 55kDa protein, were labelled in vivo and the degree of radiolabel incorporated into these proteins varied inversely with PAD activity.Ph. D.
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Santos, Roseli Machado dos. "Perda de matéria orgânica dissolvida por células flutuantes de cianobactérias potencialmente tóxicas expostas a altas intensidades de luz." Universidade Federal de São Carlos, 2006. https://repositorio.ufscar.br/handle/ufscar/1913.
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Previous issue date: 2006-08-28Universidade Federal de Sao Carlos
Anabaena spiroides and Microcystis aeruginosa are cyanobacteria that frequently bloom in Barra Bonita Reservoir. These floating organisms and the characteristic turbulence found at the reservoir exposure the cells to higher light intensities by lifting them from lower depths in the photic column to surface. The sudden exposure at higher irradiance could cause photoinhibition and photooxidation. This phenomenon could liberate high amounts of dissolved organic matter. This work aimed to investigate the carbon fixation photoinhibition in cells of A. spiroides and M. aeruginosa exposed to high irradiances, the chlorophyll photooxidation and the DOM released by cells of cultures differing in their physiologic state, after exposure to high irradiances through time at laboratory and field investigations. A. spiroides suffered photoinhibition and liberation of dissolved organic matter when exposed to irradiances higher than their EK during four hours as well as when exposed to irradiance of 2000 µmol.m-2.s-1 for eight hours. M. aeruginosa did not present photoinhibition in any case, however, their C14OD liberation was significantly increased. The higher indexes of C14OD excreted by theses cyanobacteria are not apparently due to cell damage. Hence it might represent an adaptation factor to higher irradiances. Similar results were found in experiments incubated in Barra Bonita reservoir.
Anabaena spiroides e Microcystis aeruginosa são cianobactérias que frequentemente formam florescimentos no Reservatório de Barra Bonita. A flutuação desses organismos e a turbulência característica do reservatório fazem com que as células que estavam iniciando o desenvolvimento do florescimento nas camadas inferiores da coluna fótica possam rapidamente ficar expostas a altas intensidades de luz quando na superfície. Esta exposição repentina a irradiâncias maiores pode causar fotoinibição e mesmo fotooxidação, podendo causar a liberar uma grande quantidade de matéria orgânica dissolvida pelas células. O presente trabalho foi realizado com o intuito de verificar se células de diferentes idades de cultivo de A. spiroides e M. aeruginosa sofrem fotoinibição da fixação de carbono, fotooxidação da clorofila-a e aumento na liberação de MOD quando expostas por diferentes períodos a irradiâncias elevadas. A. spiroides apresentou fotoinibição, juntamente com o aumento na excreção de matéria orgânica dissolvida, quando exposta a irradiâncias superiores ao seu EK durante 4 horas e ao ser exposta a irradiância de 2000 µmol.m-2.s-1 durante 8 horas. M. aeruginosa não apresentou fotoinibição quando exposta a irradiâncias superiores a seu EK por 4 horas, entretanto, apresentou um incremento significativo na liberação de C14OD. As concentrações elevadas de C14OD excretado pelas duas cianobactérias, aparentemente, não resultam de danos nas células, podendo representar um fator de adaptação às irradiâncias elevadas a que foram submetidas. Respostas semelhantes foram encontradas nos experimentos realizados no reservatório de Barra Bonita.
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Choueri, Rodrigo Brasil. "Consumo e influência de exopolissacarideos de Anabaena spiroides (Cyanophyceae) sobre a toxicidade e captura do cobre por Ceriodaphnia cornuta (Cladocera, Daphnidae)." Universidade Federal de São Carlos, 2004. https://repositorio.ufscar.br/handle/ufscar/2068.
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Previous issue date: 2004-05-13Financiadora de Estudos e Projetos
Human specie can alter deeply and very fast the enviroment in which it is in. Because of the industrial development, the water, air and soil contamination have become cause of concern, chiefly in big cities with great populations. Among the contaminants figure the heavy metals, which levels at aquatic and terrestrial ecossistems are growin up every year. These elements are able to bioaccumulate in the organisms and biomagnified on the food webs. The bioavailability of metals can be influencied by several factors like the complexation with dissolved organic matter, e.g. algal exudates, that generally decreases the toxicity of this elements. The scope of this work was evaluate the potencial use of exopolysccharides of Anabaena spiroides (Cyanophyceae) as food source of Ceriodaphnia cornuta (Cladocera, Daphnidae), and to establish the influence of this organic matter on copper toxicity and uptake to this cladoceran. Initially, it was estabilished the C. cornuta length-weigth relation. After this, it was investigated ingestion of exopolysccharide and its influence in life history parameters of C. cornuta. Results showed that A. spiroides exopolysccharide is able to sustain a population of this zooplanktonic specie. Individuals fed with this compound exhibited rate of population growth very significant to this specie (r = 0,263). The copper acute toxicity and uptake by C. cornuta assay revealed that addition of 30mg L-1 of A. spiroides exopolysccharide increased about 4 times copper EC/50 (calculated by Trimmed Spearman-Karber method) to C. Cornuta (from 8,11x10-8M ±9,80x10-9M without exopolysccharide to 3,25x10-7M ±5,30x10-8M with addition of exopolysccharide). Copper concentration in the organisms after 24 hours exposure to several metal concentration was determined by DPASV using a polarograph and showed little variation among concentrations and treatments with and without exopolysccharide. It suggests that organisms of this study were able to regulate copper body contents.
A espécie humana altera profundamente e com grande rapidez o ambiente no qual se insere. Com o desenvolvimento industrial, a contaminação da água, do ar e do solo tornou-se preocupante, sobretudo nas grandes cidades densamente povoadas. Dentre os contaminantes, estão os metais pesados, cujos níveis nos ecossistemas aquáticos e terrestres vêm aumentando a cada ano. Esses elementos podem ser bioacumulados nos organismos e biomagnificados nas cadeias tróficas. A biodisponibilidade de metais pode ser influenciada por vários fatores, entre eles, a formação de complexos com a matéria orgânica dissolvida, como exudatos algais, que geralmente diminui a toxicidade desses elementos. O escopo deste trabalho foi avaliar o uso potencial de exopolissacarídeos de Anabaena spiroides (Cyanophyceae) como fonte alimentar de Ceriodaphnia cornuta (Cladocera, Daphnidae), bem como determinar a influência dessa matéria orgânica na toxicidade e captura do cobre por esse cladócero. Inicialmente, foi confeccionada uma regressão peso seco (µg) comprimento (mm) para Ceriodaphnia cornuta. Em seguida, foi investigada a ingestão do exopolissacarídeo por C. cornuta e a influência desse tipo de alimento em parâmetros bionômicos dessa espécie zooplanctônica. Os resultados demonstraram que o exopolissacarídeo A. spiroides é capaz de sustentar uma população de C. cornuta. Os animais alimentados com esse composto apresentaram taxa de crescimento populacional (r) de 0,263, bastante significativa para a espécie. O experimento de toxicidade e captura de cobre por C. cornuta revelou que a adição de 30mg L-1 de exopolissacarídeo de A. spiroides aumentou em aproximadamente 4 vezes a EC/50 (calculada pelo método Trimmed Spearman-Karber ) do cobre para C. Cornuta (de 8,11x10-8M ±9,80x10- 9M - sem exopolissacarídeo - para 3,25x10-7M ±5,30x10-8M com exopolissacarídeo). As concentrações de cobre nos organismos após 24 horas de exposição a diferentes concentrações do metal no meio experimental foram determinadas em polarógrafo através da técnica de DPASV e demonstraram pouca variação entre concentrações e entre os tratamentos com e sem exopolissacarídeos, o que sugere que os organismos testados regulem o conteúdo de cobre no corpo.
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Aryal, Deepak Aryal. "Evaluating The Effectiveness Of Algaecide In A Continuous Flow Through System." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1533137036461609.
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Marques, Ana Cristina Evangelista. "Produção de biohidrogénio por cianobactérias: optimização da produção de biohidrogénio pela Anabaena sp. PCC 7120 wild type e mutantes." Master's thesis, Faculdade de Ciências e Tecnologia, 2014. http://hdl.handle.net/10362/12332.
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Morales, Renaud. "Association et dissociation de deux protéines de la photosynthèse : étude cristallographique du complexe ferrédoxine NADP+ réductase/ferrédoxine chez Anabaena PCC7119." Grenoble 1, 2000. http://www.theses.fr/2000GRE10251.
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La ferredoxine-nadp + reductase (fnr) catalyse l'etape terminale de la photosynthese qui transforme l'energie lumineuse en energie chimique. La fnr utilise deux electrons de haute energie photoproduits par le photosysteme i (psi) et transportes, un par un, par une ferredoxine reduite pour permettre la reduction du nadp + en nadph. Le pouvoir reducteur du nadph est ensuite utilise dans les mecanismes d'assimilation du carbone. Dans un premier temps, nous nous sommes interesses a l'etude cristallographique de la fnr et de la fd isolees et dans leurs differents etats d'oxydoreduction. Les structures a tres haute resolution de la fd oxydee (1. 3 a) et reduite (1. 2 a) ont permis de mettre en evidence un changement conformationnel de la chaine principale. En revanche la structure reduite du complexe entre la fnr et son cofacteur le nadp + (1. 8 a), ne presente pas de differences majeurs avec la structure oxydee. L'interaction entre la fnr et la fd oxydees a ete etudiee par cristallographie. Pour les calculs d'affinement (realises a 2. 4 a de resolution), les cristaux ont ete traite comme une macle. Cela a permis de construire le premier modele de complexe entre une fd et une fnr issue de la cyanobacterie anabaena. L'ensemble de ces travaux nous ont permis de montrer qu'une interaction specifique avait lieu entre la fnr et la fd, permettant le transfert d'electron, puis que ces deux proteines se dissociaient vraisemblablement par un mecanisme lie a l'etat d'oxydation de la fd et notamment au changement conformationnel observe chez cette petite proteine a centre fer-soufre. (252).
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Darnajoux, Romain Nicolas Xavier. "Étude de l'homéostasie des micronutriments de la fixation d'azote au sein de la symbiose lichénique en forêt boréale." Thèse, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/7572.
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L’azote est un des éléments les plus importants dans la nature. Sa disponibilité limite la productivité d’un grand nombre d’écosystèmes naturels, et influencera sans doute de manière importante leurs réponses aux changements climatiques globaux. La première source d’azote dans les écosystèmes non anthropisés est la fixation biologique de l’azote. Ce processus repose sur un groupe de métallo-enzymes spécifiques, les nitrogénases, dont le cofacteur métallique contient soit du fer et un atome de molybdène, soit du fer et un atome de vanadium, soit uniquement du fer. A ce jour, seule la nitrogénase au molybdène est prise en considération dans la dynamique de l’azote dans les écosystèmes, et ce malgré de nombreux indices indiquant que la nitrogénase au vanadium pourrait avoir un rôle important. Est-ce que la nitrogénase au vanadium est utilisée dans les écosystèmes naturels et quelles sont les conditions favorisant son utilisation ?
Nous avons cherché à répondre à ces questions à l’aide d’un modèle symbiotique tripartite, un lichen, association entre une algue, un champignon et une cyanobactérie fixatrice d’azote. Nous avons tout d’abord développé une méthode d’étude des contenus en métaux des différents symbiontes, puis nous avons étudié la répartition et la régulation du vanadium au sein des différents symbiontes dans différentes conditions environnementales. Nous avons pu démontrer que dans ce modèle, le vanadium possède toutes les caractéristiques d’un micronutriment essentiel à la fixation d’azote. Nous avons également démontré que la disponibilité du molybdène ainsi que les températures, telles que rencontrées en milieux boréaux, seraient deux facteurs importants contrôlant l’utilisation de la V-Nase.
Les résultats présentés dans cette étude apportent une meilleure compréhension de la gestion des métaux cofacteurs de la nitrogénase au sein de la symbiose lichénique. Mais ils permettent surtout de remettre en question le paradigme de l’hégémonie du molybdène sur la fixation biologique de l’azote. Ainsi, la fixation d’azote en milieu continental repose sur un ensemble hétérogène d’enzymes, ce qui autorise aux organismes fixateurs d’azote une grande flexibilité vis-à-vis des paramètres environnementaux comme les basses températures. Cela leurs permet également une meilleure adaptation au stress métallique résultant de carences en micronutriments, notamment celle en molybdène. Ces résultats invitent également à réévaluer les modèles biogéochimiques liant les cycles des micronutriments aux cycles des macronutriments, particulièrement celui de l’azote.
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Bringuier, Charline. "Effet des changements climatiques et atmosphériques sur la croissance et la fixation biologique de l'azote chez Anabaena variabilis : importance des disponibilités du molybdène et du phosphore." Mémoire, Université de Sherbrooke, 2016. http://hdl.handle.net/11143/8790.
Full textAbstract:
La fixation biologique d’azote réalisée par les cyanobactéries est un processus important dans les écosystèmes où la productivité est limitée par la disponibilité de l’azote. Dans des conditions de changements globaux, l’augmentation du CO2 atmosphérique pourrait engendrer une augmentation des taux de fixation d’azote permettant de combler la demande croissante d’azote nécessaire à la croissance. Cependant cette augmentation des taux de fixation d’azote pourrait dépendre des disponibilités en molybdène (Mo) et en phosphore (P), mais également être contrebalancée par l’azote minéral apporté via les dépositions atmosphériques.
La complexité des systèmes naturels, notamment les caractéristiques de la symbiose cyanobactérie-végétaux supérieurs rends difficile l’étude de l’effet de l’augmentation du CO2 et des dépositions atmosphérique sur la fixation d’azote, dépendamment des disponibilités en Mo et P. Nous avons donc tenté de déterminer les effets de ces facteurs environnementaux (CO2 et apport d’azote minéral), en utilisant des cultures pures de cyanobactéries (Anabaena variabilis) dans différentes conditions de disponibilités en Mo et P. Cette approche expérimentale réductionniste nous a permis de mettre en évidence un effet significatif du P sur la concentration de la chlorophylle, indépendant des conditions environnementales (CO2, N) ainsi qu’une interaction entre le Mo et le P pour la variable chlorophylle, dans des conditions de CO2 augmenté sans apport d’azote. Cette interaction entre le Mo et le P pourrait être expliquée par un compromis entre l’acquisition du carbone, facilitée dans des conditions de CO2 augmentée, et la fixation biologique d’azote. Notre étude a également permis de mettre en évidence un effet significatif du P sur la croissance d’A. variabilis, dans des conditions de CO2 ambient et en présence d’azote. De façon plus spécifique, à haut P (2.5 10-5 M) le taux de croissance était plus faible (P = 0.02), alors que la quantité de chlorophylle et l’activité de la nitrogénase étaient toutes deux plus élevée (P = 0.002 et P = 0.015 respectivement). Cet effet du P pourrait être expliqué par une différence de stratégie de croissance de la cyanobactérie. A faible P, la cyanobactérie pourrait investir dans de courts filaments composés de cellules volumineuses, contrairement à des conditions de concentration en P élevées, où la cyanobactérie pourrait investir plus dans la formation d’hétérocystes et de filaments plus longs, composés de cellules plus petites.
Cette étude apporte des pistes de réflexion quant aux stratégies permettant aux cyanobactéries filamenteuses de s’adapter à l’augmentation du CO2 atmosphérique et des dépositions azotées, en fonction des disponibilités en Mo et P. Un compromis entre l’acquisition de C et la fixation d’azote ou un changement de la stratégie de croissance des filaments pourrait permettre aux cyanobactéries filamenteuses d’être moins sensibles aux stress environnementaux (augmentation du CO2 atmosphérique et disponibilité des nutriments tels que l’azote).