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Sample records for diazotrophic cyanobacterium important

  1. The genome of Cyanothece 51142, a unicellular diazotrophic cyanobacterium important in the marine nitrogen cycle

    Energy Technology Data Exchange (ETDEWEB)

    Welsh, Eric A.; Liberton, Michelle L.; Stockel, Jana; Loh, Thomas; Elvitigala, Thanura R.; Wang, Chunyan; Wollam, Aye; Fulton, Robert S.; Clifton, Sandra W.; Jacobs, Jon M.; Aurora, Rajeev; Ghosh, Bijoy K.; Sherman, Louis A.; Smith, Richard D.; Wilson, Richard K.; Pakrasi, Himadri B.

    2008-09-30

    Cyanobacteria are oxygenic photosynthetic bacteria that have significant roles in global biological carbon sequestration and oxygen production. They occupy a diverse range of habitats, from open ocean, to hot springs, deserts, and arctic waters. Cyanobacteria are known as the progenitors of the chloroplasts of plants and algae, and are the simplest known organisms to exhibit circadian behavior4. Cyanothece sp. ATCC 51142 is a unicellular marine cyanobacterium capable of N2-fixation, a process that is biochemically incompatible with oxygenic photosynthesis. To resolve this problem, Cyanothece performs photosynthesis during the day and nitrogen fixation at night, thus temporally separating these processes in the same cell. The genome of Cyanothece 51142 was completely sequenced and found to contain a unique arrangement of one large circular chromosome, four small plasmids, and one linear chromosome, the first report of such a linear element in a photosynthetic bacterium. Annotation of the Cyanothece genome was aided by the use of highthroughput proteomics data, enabling the reclassification of 25% of the proteins with no informative sequence homology. Phylogenetic analysis suggests that nitrogen fixation is an ancient process that arose early in evolution and has subsequently been lost in many cyanobacterial strains. In cyanobacterial cells, the circadian clock influences numerous processes, including carbohydrate synthesis, nitrogen fixation, photosynthesis, respiration, and the cell division cycle. During a diurnal period, Cyanothece cells actively accumulate and degrade different storage inclusion bodies for the products of photosynthesis and N2-fixation. This ability to utilize metabolic compartmentalization and energy storage makes Cyanothece an ideal system for bioenergy research, as well as studies of how a unicellular organism balances multiple, often incompatible, processes in the same cell.

  2. Ecological genomics of the newly discovered diazotrophic filamentous cyanobacterium ESFC-1

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    Everroad, C.; Bebout, B.; Bebout, L. E.; Detweiler, A. M.; Lee, J.; Mayali, X.; Singer, S. W.; Stuart, R.; Weber, P. K.; Woebken, D.; Pett-Ridge, J.

    2014-12-01

    Cyanobacteria-dominated microbial mats played a key role in the evolution of the early Earth and provide a model for exploring the relationships between ecology, evolution and biogeochemistry. A recently described nonheterocystous filamentous cyanobacterium, strain ESFC-1, has been shown to be a major diazotroph year round in the intertidal microbial mat system at Elkhorn Slough, CA, USA. Based on phylogenetic analyses of the 16s RNA gene, ESFC-1 appears to belong to a unique, genus-level divergence within the cyanobacteria. Consequently, the draft genome sequence of this strain has been determined. Here we report features of this genome, particularly as they relate to the ecological functions and capabilities of strain ESFC-1. One striking feature of this cyanobacterium is the apparent lack of a functional bi-directional hydrogenase typically expected to be found within a diazotroph; consortia- and culture-based experiments exploring the metabolic processes of ESFC-1 also indicate that this hydrogenase is absent. Co-culture studies with ESFC-1 and some of the dominant heterotrophic members within the microbial mat system, including the ubiquitous Flavobacterium Muricauda sp., which often is found associated with cyanobacteria in nature and in culture collections worldwide, have also been performed. We report on these species-species interactions, including materials exchange between the cyanobacterium and heterotrophic bacterium. The combination of genomics with culture- and consortia-based experimental research is a powerful tool for understanding microbial processes and interactions in complex ecosystems.

  3. Evidence for polyploidy in the globally important diazotroph Trichodesmium

    OpenAIRE

    Sargent, Elizabeth C.; Hitchcock, Andrew; Johansson, Andreas; Langlois, Rebecca; Moore, Mark; LaRoche, Julie; Poulton, Alex; Bibby, Thomas S.

    2016-01-01

    Polyploidy is a well-described trait in some prokaryotic organisms; however, it is unusual in marine microbes from oligotrophic environments, which typically display a tendency towards genome streamlining. The biogeochemically significant diazotrophic cyanobacterium Trichodesmium is a potential exception. With a relatively large genome and a comparatively high proportion of non-protein-coding DNA, Trichodesmium appears to allocate relatively more resources to genetic material than closely rel...

  4. Evolving interactions between diazotrophic cyanobacterium and phage mediate nitrogen release and host competitive ability

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    Coloma, Sebastián; Sivonen, Kaarina

    2016-01-01

    Interactions between nitrogen-fixing (i.e. diazotrophic) cyanobacteria and their viruses, cyanophages, can have large-scale ecosystem effects. These effects are mediated by temporal alterations in nutrient availability in aquatic systems owing to the release of nitrogen and carbon sources from cells lysed by phages, as well as by ecologically important changes in the diversity and fitness of cyanobacterial populations that evolve in the presence of phages. However, ecological and evolutionary feedbacks between phages and nitrogen-fixing cyanobacteria are still relative poorly understood. Here, we used an experimental evolution approach to test the effect of interactions between a common filamentous, nitrogen-fixing cyanobacterium (Nodularia sp.) and its phage on cellular nitrogen release and host properties. Ecological, community-level effects of phage-mediated nitrogen release were tested with a phytoplankton bioassay. We found that cyanobacterial nitrogen release increased significantly as a result of viral lysis, which was associated with enhanced growth of phytoplankton species in cell-free filtrates compared with phage-resistant host controls in which lysis and subsequent nutrient release did not occur after phage exposure. We also observed an ecologically important change among phage-evolved cyanobacteria with phage-resistant phenotypes, a short-filamentous morphotype with reduced buoyancy compared with the ancestral long-filamentous morphotype. Reduced buoyancy might decrease the ability of these morphotypes to compete for light compared with longer, more buoyant filaments. Together, these findings demonstrate the potential of cyanobacteria–phage interactions to affect ecosystem biogeochemical cycles and planktonic community dynamics. PMID:28083116

  5. Diazotrophic specific cytochrome c oxidase required to overcome light stress in the cyanobacterium Nostoc muscorum.

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    Bhargava, Santosh; Chouhan, Shweta

    2016-01-01

    Diazotrophic, filamentous and heterocystous cyanobacterium Nostoc muscorum perform photosynthesis in vegetative whereas nitrogen fixation occurs in heterocyst only. However, despite their metabolic plasticity, respiration takes place both in vegetative cells and heterocysts. The role of the respiratory electron transport system and terminal oxidases under light stress is not evident so far. As compared to the diazotrophically grown cultures, the non-diazotrophically grown cultures of the N. muscorum show a slight decrease in their growth, chlorophyll a contents and photosynthetic O2 evolution under light stress. Whereas respiratory O2 uptake under identical stress condition increases several fold. Likewise, nitrogen fixing enzyme i.e. nitrogenase over-expresses itself under light stress condition. The terminal enzyme of respiratory electron transport chain i.e. cytochrome c oxidase shows more activity under light stress, whilst light stress has no impact on Ca(++)-dependent ATPase activity. This leads to the conclusion that under light stress, cytochrome c oxidase plays a vital role in mitigating given light stress.

  6. Genome-scale modeling of light-driven reductant partitioning and carbon fluxes in diazotrophic unicellular cyanobacterium Cyanothece sp. ATCC 51142.

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    Trang T Vu

    Full Text Available Genome-scale metabolic models have proven useful for answering fundamental questions about metabolic capabilities of a variety of microorganisms, as well as informing their metabolic engineering. However, only a few models are available for oxygenic photosynthetic microorganisms, particularly in cyanobacteria in which photosynthetic and respiratory electron transport chains (ETC share components. We addressed the complexity of cyanobacterial ETC by developing a genome-scale model for the diazotrophic cyanobacterium, Cyanothece sp. ATCC 51142. The resulting metabolic reconstruction, iCce806, consists of 806 genes associated with 667 metabolic reactions and includes a detailed representation of the ETC and a biomass equation based on experimental measurements. Both computational and experimental approaches were used to investigate light-driven metabolism in Cyanothece sp. ATCC 51142, with a particular focus on reductant production and partitioning within the ETC. The simulation results suggest that growth and metabolic flux distributions are substantially impacted by the relative amounts of light going into the individual photosystems. When growth is limited by the flux through photosystem I, terminal respiratory oxidases are predicted to be an important mechanism for removing excess reductant. Similarly, under photosystem II flux limitation, excess electron carriers must be removed via cyclic electron transport. Furthermore, in silico calculations were in good quantitative agreement with the measured growth rates whereas predictions of reaction usage were qualitatively consistent with protein and mRNA expression data, which we used to further improve the resolution of intracellular flux values.

  7. Genome-scale modeling of light-driven reductant partitioning and carbon fluxes in diazotrophic unicellular cyanobacterium Cyanothece sp. ATCC 51142.

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    Vu, Trang T; Stolyar, Sergey M; Pinchuk, Grigoriy E; Hill, Eric A; Kucek, Leo A; Brown, Roslyn N; Lipton, Mary S; Osterman, Andrei; Fredrickson, Jim K; Konopka, Allan E; Beliaev, Alexander S; Reed, Jennifer L

    2012-01-01

    Genome-scale metabolic models have proven useful for answering fundamental questions about metabolic capabilities of a variety of microorganisms, as well as informing their metabolic engineering. However, only a few models are available for oxygenic photosynthetic microorganisms, particularly in cyanobacteria in which photosynthetic and respiratory electron transport chains (ETC) share components. We addressed the complexity of cyanobacterial ETC by developing a genome-scale model for the diazotrophic cyanobacterium, Cyanothece sp. ATCC 51142. The resulting metabolic reconstruction, iCce806, consists of 806 genes associated with 667 metabolic reactions and includes a detailed representation of the ETC and a biomass equation based on experimental measurements. Both computational and experimental approaches were used to investigate light-driven metabolism in Cyanothece sp. ATCC 51142, with a particular focus on reductant production and partitioning within the ETC. The simulation results suggest that growth and metabolic flux distributions are substantially impacted by the relative amounts of light going into the individual photosystems. When growth is limited by the flux through photosystem I, terminal respiratory oxidases are predicted to be an important mechanism for removing excess reductant. Similarly, under photosystem II flux limitation, excess electron carriers must be removed via cyclic electron transport. Furthermore, in silico calculations were in good quantitative agreement with the measured growth rates whereas predictions of reaction usage were qualitatively consistent with protein and mRNA expression data, which we used to further improve the resolution of intracellular flux values.

  8. Transcriptional analysis of the unicellular, diazotrophic cyanobacterium Cyanothece sp. ATCC 51142 grown under short day/night cycles

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    Toepel, Jorg; McDermott, Jason E.; Summerfield, Tina; Sherman, Louis A.

    2009-06-01

    Cyanothece sp. strain ATCC 51142 is a unicellular, diazotrophic cyanobacterium that demonstrates extensive metabolic periodicities of photosynthesis, respiration and nitrogen fixation when grown under N2-fixing conditions. We have performed a global transcription analysis of this organism using 6 h light/dark cycles in order to determine the response of the cell to these conditions and to differentiate between diurnal and circadian regulated genes. In addition, we used a context-likelihood of relatedness (CLR) analysis with this data and those from two-day light/dark and light-dark plus continuous light experiments to better differentiate between diurnal and circadian regulated genes. Cyanothece sp. adapted in several ways to growth under short light/dark conditions. Nitrogen was fixed in every second dark period and only once in each 24 h period. Nitrogen fixation was strongly correlated to the energy status of the cells and glycogen breakdown and high respiration rates were necessary to provide appropriate energy and anoxic conditions for this process. We conclude that glycogen breakdown is a key regulatory step within these complex processes. Our results demonstrated that the main metabolic genes involved in photosynthesis, respiration, nitrogen fixation and central carbohydrate metabolism have strong (or total) circadian-regulated components. The short light/dark cycles enable us to identify transcriptional differences among the family of psbA genes, as well as the differing patterns of the hup genes, which follow the same pattern as nitrogenase genes, relative to the hox genes which displayed a diurnal, dark-dependent gene expression.

  9. Analysis of carbohydrate storage granules in the diazotrophic cyanobacterium Cyanothece sp. PCC 7822

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    Welkie, David G. [Purdue Univ., West Lafayette, IN (United States); Sherman, Debra M. [Purdue Univ., West Lafayette, IN (United States); Chrisler, William B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Orr, Galya [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sherman, Louis A. [Purdue Univ., West Lafayette, IN (United States)

    2013-10-19

    The unicellular diazotrophic cyanobacteria of the genus Cyanothece demonstrate oscillations in nitrogenase activity and H2 production when grown under 12h light-12h dark cycles. We established that Cyanothece sp. PCC 7822 allows for the construction of knock-out mutants and our objective was to improve the growth characteristics of this strain and to identify the nature of the intracellular storage granules. We report the physiological and morphological effects of reduction in nitrate and phosphate concentrations in BG-11 media on this strain. We developed a series of BG-11-derived growth media and monitored batch culture growth, nitrogenase activity and nitrogenase-mediated hydrogen production, culture synchronicity, and intracellular storage content. Reduction in NaNO3 and K2HPO4 concentrations from 17.6 and 0.23 mM to 4.41 and 0.06 mM, respectively, improved growth characteristics such as cell size and uniformity, and enhanced the rate of cell division. Cells grown in this low NP BG-11 were less complex, a parameter that related to the composition of the intracellular storage granules. Cells grown in low NP BG-11 had less polyphosphate, fewer polyhydroxybutyrate granules and many smaller granules became evident. Biochemical analysis and transmission electron microscopy using the histocytochemical PATO technique demonstrated that these small granules contained glycogen. The glycogen levels and the number of granules per cell correlated nicely with a 2.3 to 3.3-fold change from the minimum at L0 to the maximum at D0. The differences in granule morphology and enzymes between Cyanothece ATCC 51142 and Cyanothece PCC 7822 provide insights into the formation of large starch-like granules in some cyanobacteria.

  10. Inactivation of agmatinase expressed in vegetative cells alters arginine catabolism and prevents diazotrophic growth in the heterocyst-forming cyanobacterium Anabaena.

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    Burnat, Mireia; Flores, Enrique

    2014-10-01

    Arginine decarboxylase produces agmatine, and arginase and agmatinase are ureohydrolases that catalyze the production of ornithine and putrescine from arginine and agmatine, respectively, releasing urea. In the genome of the filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120, ORF alr2310 putatively encodes an ureohydrolase. Cells of Anabaena supplemented with [(14) C]arginine took up and catabolized this amino acid generating a set of labeled amino acids that included ornithine, proline, and glutamate. In an alr2310 deletion mutant, an agmatine spot appeared and labeled glutamate increased with respect to the wild type, suggesting that Alr2310 is an agmatinase rather than an arginase. As determined in cell-free extracts, agmatinase activity could be detected in the wild type but not in the mutant. Thus, alr2310 is the Anabaena speB gene encoding agmatinase. The ∆alr2310 mutant accumulated large amounts of cyanophycin granule polypeptide, lacked nitrogenase activity, and did not grow diazotrophically. Growth tests in solid media showed that agmatine is inhibitory for Anabaena, especially under diazotrophic conditions, suggesting that growth of the mutant is inhibited by non-metabolized agmatine. Measurements of incorporation of radioactivity from [(14) C]leucine into macromolecules showed, however, a limited inhibition of protein synthesis in the ∆alr2310 mutant. Analysis of an Anabaena strain producing an Alr2310-GFP (green fluorescent protein) fusion showed expression in vegetative cells but much less in heterocysts, implying compartmentalization of the arginine decarboxylation pathway in the diazotrophic filaments of this heterocyst-forming cyanobacterium.

  11. Involvement of thioredoxin on the scaffold activity of NifU in heterocyst cells of the diazotrophic cyanobacterium Anabaena sp. strain PCC 7120.

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    Nomata, Jiro; Maeda, Maki; Isu, Atsuko; Inoue, Kazuhito; Hisabori, Toru

    2015-09-01

    The diazotrophic cyanobacterium Anabaena sp. strain PCC 7120 (A.7120) differentiates into specialized heterocyst cells that fix nitrogen under nitrogen starvation conditions. Although reducing equivalents are essential for nitrogen fixation, little is known about redox systems in heterocyst cells. In this study, we investigated thioredoxin (Trx) networks in Anabaena using TrxM, and identified 16 and 38 candidate target proteins in heterocysts and vegetative cells, respectively, by Trx affinity chromatography (Motohashi et al. (Comprehensive survey of proteins targeted by chloroplast thioredoxin. Proc Natl Acad Sci USA, 2001; 98: , 11224-11229)). Among these, the Fe-S cluster scaffold protein NifU that facilitates functional expression of nitrogenase in heterocysts was found to be a potential TrxM target. Subsequently, we observed that the scaffold activity of N-terminal catalytic domain of NifU is enhanced in the presence of Trx-system, suggesting that TrxM is involved in the Fe-S cluster biogenesis.

  12. Analysis of the early heterocyst Cys-proteome in the multicellular cyanobacterium Nostoc punctiforme reveals novel insights into the division of labor within diazotrophic filaments.

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    Sandh, Gustaf; Ramström, Margareta; Stensjö, Karin

    2014-12-04

    In the filamentous cyanobacterium Nostoc punctiforme ATCC 29133, removal of combined nitrogen induces the differentiation of heterocysts, a cell-type specialized in N2 fixation. The differentiation involves genomic, structural and metabolic adaptations. In cyanobacteria, changes in the availability of carbon and nitrogen have also been linked to redox regulated posttranslational modifications of protein bound thiol groups. We have here employed a thiol targeting strategy to relatively quantify the putative redox proteome in heterocysts as compared to N2-fixing filaments, 24 hours after combined nitrogen depletion. The aim of the study was to expand the coverage of the cell-type specific proteome and metabolic landscape of heterocysts. Here we report the first cell-type specific proteome of newly formed heterocysts, compared to N2-fixing filaments, using the cysteine-specific selective ICAT methodology. The data set defined a good quantitative accuracy of the ICAT reagent in complex protein samples. The relative abundance levels of 511 proteins were determined and 74% showed a cell-type specific differential abundance. The majority of the identified proteins have not previously been quantified at the cell-type specific level. We have in addition analyzed the cell-type specific differential abundance of a large section of proteins quantified in both newly formed and steady-state diazotrophic cultures in N. punctiforme. The results describe a wide distribution of members of the putative redox regulated Cys-proteome in the central metabolism of both vegetative cells and heterocysts of N. punctiforme. The data set broadens our understanding of heterocysts and describes novel proteins involved in heterocyst physiology, including signaling and regulatory proteins as well as a large number of proteins with unknown function. Significant differences in cell-type specific abundance levels were present in the cell-type specific proteomes of newly formed diazotrophic filaments

  13. Heterocyst-specific flavodiiron protein Flv3B enables oxic diazotrophic growth of the filamentous cyanobacterium Anabaena sp. PCC 7120.

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    Ermakova, Maria; Battchikova, Natalia; Richaud, Pierre; Leino, Hannu; Kosourov, Sergey; Isojärvi, Janne; Peltier, Gilles; Flores, Enrique; Cournac, Laurent; Allahverdiyeva, Yagut; Aro, Eva-Mari

    2014-07-29

    Flavodiiron proteins are known to have crucial and specific roles in photoprotection of photosystems I and II in cyanobacteria. The filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 contains, besides the four flavodiiron proteins Flv1A, Flv2, Flv3A, and Flv4 present in vegetative cells, two heterocyst-specific flavodiiron proteins, Flv1B and Flv3B. Here, we demonstrate that Flv3B is responsible for light-induced O2 uptake in heterocysts, and that the absence of the Flv3B protein severely compromises the growth of filaments in oxic, but not in microoxic, conditions. It is further demonstrated that Flv3B-mediated photosynthetic O2 uptake has a distinct role in heterocysts which cannot be substituted by respiratory O2 uptake in the protection of nitrogenase from oxidative damage and, thus, in an efficient provision of nitrogen to filaments. In line with this conclusion, the Δflv3B strain has reduced amounts of nitrogenase NifHDK subunits and shows multiple symptoms of nitrogen deficiency in the filaments. The apparent imbalance of cytosolic redox state in Δflv3B heterocysts also has a pronounced influence on the amounts of different transcripts and proteins. Therefore, an O2-related mechanism for control of gene expression is suggested to take place in heterocysts.

  14. Comparisons of diazotrophic communities in native and agricultural desert ecosystems reveal plants as important drivers in diversity.

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    Köberl, Martina; Erlacher, Armin; Ramadan, Elshahat M; El-Arabi, Tarek F; Müller, Henry; Bragina, Anastasia; Berg, Gabriele

    2016-02-01

    Diazotrophs provide the only biological source of fixed atmospheric nitrogen in the biosphere. Although they are the key player for plant-available nitrogen, less is known about their diversity and potential importance in arid ecosystems. We investigated the nitrogenase gene diversity in native and agricultural desert soil as well as within root-associated microbiota of medicinal plants grown in Egypt through the combination of nifH-specific qPCR, fingerprints, amplicon pyrosequencing and fluorescence in situ hybridization-confocal laser scanning microscopy. Although the diazotrophic microbiota were characterized by generally high abundances and diversity, statistically significant differences were found between both soils, the different microhabitats, and between the investigated plants (Matricaria chamomilla L., Calendula officinalis L. and Solanum distichum Schumach. and Thonn.). We observed a considerable community shift from desert to agriculturally used soil that demonstrated a higher abundance and diversity in the agro-ecosystem. The endorhiza was characterized by lower abundances and only a subset of species when compared to the rhizosphere. While the microbiomes of the Asteraceae were similar and dominated by potential root-nodulating rhizobia acquired primarily from soil, the perennial S. distichum generally formed associations with free-living nitrogen fixers. These results underline the importance of diazotrophs in desert ecosystems and additionally identify plants as important drivers in functional gene pool diversity.

  15. Comparisons of diazotrophic communities in native and agricultural desert ecosystems reveal plants as important drivers in diversity

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    Köberl, Martina; Erlacher, Armin; Ramadan, Elshahat M.; El-Arabi, Tarek F.; Müller, Henry; Bragina, Anastasia; Berg, Gabriele

    2015-01-01

    Diazotrophs provide the only biological source of fixed atmospheric nitrogen in the biosphere. Although they are the key player for plant-available nitrogen, less is known about their diversity and potential importance in arid ecosystems. We investigated the nitrogenase gene diversity in native and agricultural desert soil as well as within root-associated microbiota of medicinal plants grown in Egypt through the combination of nifH-specific qPCR, fingerprints, amplicon pyrosequencing and fluorescence in situ hybridization–confocal laser scanning microscopy. Although the diazotrophic microbiota were characterized by generally high abundances and diversity, statistically significant differences were found between both soils, the different microhabitats, and between the investigated plants (Matricaria chamomilla L., Calendula officinalis L. and Solanum distichum Schumach. and Thonn.). We observed a considerable community shift from desert to agriculturally used soil that demonstrated a higher abundance and diversity in the agro-ecosystem. The endorhiza was characterized by lower abundances and only a subset of species when compared to the rhizosphere. While the microbiomes of the Asteraceae were similar and dominated by potential root-nodulating rhizobia acquired primarily from soil, the perennial S. distichum generally formed associations with free-living nitrogen fixers. These results underline the importance of diazotrophs in desert ecosystems and additionally identify plants as important drivers in functional gene pool diversity. PMID:26705571

  16. A common transport system for methionine, L-methionine-DL-sulfoximine (MSX), and phosphinothricin (PPT) in the diazotrophic cyanobacterium Nostoc muscorum.

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    Singh, Arvind Kumar; Syiem, Mayashree B; Singh, Rajkumar S; Adhikari, Samrat; Rai, Amar Nath

    2008-05-01

    We present evidence, for the first time, of the occurrence of a transport system common for amino acid methionine, and methionine/glutamate analogues L-methionine-DL-sulfoximine (MSX) and phosphinothricin (PPT) in cyanobacterium Nostoc muscorum. Methionine, which is toxic to cyanobacterium, enhanced its nitrogenase activity at lower concentrations. The cyanobacterium showed a biphasic pattern of methionine uptake activity that was competitively inhibited by the amino acids alanine, isoleucine, leucine, phenylalanine, proline, valine, glutamine, and asparagine. The methionine/glutamate analogue-resistant N. muscorum strains (MSX-R and PPT-R strains) also showed methionine-resistant phenotype accompanied by a drastic decrease in 35S methionine uptake activity. Treatment of protein extracts from these mutant strains with MSX and PPT reduced biosynthetic glutamine synthetase (GS) activity only in vitro and not in vivo. This finding implicated that MSX- and PPT-R phenotypes may have arisen due to a defect in their MSX and PPT transport activity. The simultaneous decrease in methionine uptake activity and in vitro sensitivity toward MSX and PPT of GS protein in MSX- and PPT-R strains indicated that methionine, MSX, and PPT have a common transport system that is shared by other amino acids as well in N. muscorum. Such information can become useful for isolation of methionine-producing cyanobacterial strains.

  17. Lipopolysaccharides in diazotrophic bacteria

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    Rodrigo Vassoler Serrato

    2014-09-01

    Full Text Available Biological nitrogen fixation is a process in which the atmospheric nitrogen (N2 is transformed into ammonia (NH3 by a select group of nitrogen-fixing organisms, or diazotrophic bacteria. In order to furnish the biologically useful nitrogen to plants, these bacteria must be in constant molecular communication with their host plants. Some of these molecular plant-microbe interactions are very specific, resulting in a symbiotic relationship between the diazotroph and the host. Others are found between associative diazotrophs and plants, resulting in plant infection and colonization of internal tissues. Independent of the type of ecological interaction, glycans and glycoconjugates produced by these bacteria play an important role in the molecular communication prior and during colonization. Even though exopolysaccharides (EPS and lipochitooligosaccharides (LCO produced by diazotrophic bacteria and released onto the environment have their importance in the microbe-plant interaction, it is the lipopolysaccharides (LPS, anchored on the external membrane of these bacteria, that mediates the direct contact of the diazotroph with the host cells. These molecules are extremely variable among the several species of nitrogen fixing-bacteria, and there are evidences of the mechanisms of infection being closely related to their structure.

  18. Lipopolysaccharides in diazotrophic bacteria.

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    Serrato, Rodrigo V

    2014-01-01

    Biological nitrogen fixation (BNF) is a process in which the atmospheric nitrogen (N2) is transformed into ammonia (NH3) by a select group of nitrogen-fixing organisms, or diazotrophic bacteria. In order to furnish the biologically useful nitrogen to plants, these bacteria must be in constant molecular communication with their host plants. Some of these molecular plant-microbe interactions are very specific, resulting in a symbiotic relationship between the diazotroph and the host. Others are found between associative diazotrophs and plants, resulting in plant infection and colonization of internal tissues. Independent of the type of ecological interaction, glycans, and glycoconjugates produced by these bacteria play an important role in the molecular communication prior and during colonization. Even though exopolysaccharides (EPS) and lipochitooligosaccharides (LCO) produced by diazotrophic bacteria and released onto the environment have their importance in the microbe-plant interaction, it is the lipopolysaccharides (LPS), anchored on the external membrane of these bacteria, that mediates the direct contact of the diazotroph with the host cells. These molecules are extremely variable among the several species of nitrogen fixing-bacteria, and there are evidences of the mechanisms of infection being closely related to their structure.

  19. The importance of diazotrophic cyanobacteria as primary producers during Cretaceous Oceanic Anoxic Event 2

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    N. Ohkouchi

    2006-01-01

    Full Text Available In Livello Bonarelli black shale deposited during Cretaceous Oceanic Anoxic Event 2 (OAE-2, ca. 94 Ma, nitrogen isotopic compositions of bulk sediments are mostly in a narrow range from –2.7 to –0.7‰. We also determined molecular distribution and nitrogen isotopic compositions of geoporphyrins extracted from the black shale. The nitrogen isotopic compositions of C32 Ni deoxophylloerythroetioporphyrin (DPEP and total Ni porphyrins are –3.5 and –3.3‰, respectively, leading us to the estimation that the mean nitrogen isotopic composition of photoautotrophic cells were around +1‰ during the formation of Bonarelli black shale. This value is suggestive of N2-fixation, a dominant process for these photoautotrophs when assimilating nitrogen. Furthermore, Ni-chelated C32 DPEP, derived mainly from chlorophyll a had the highest concentration. Based on this evidence, we conclude that diazotrophic cyanobacteria were major primary producers during that time. Cyanobacteria may be key photoautotrophs during the formation of black shale type sediments intermittently observed throughout the later half of the Earth's history, and hence may have played a crucial role in the evolution of geochemical cycles even in the later half of the Earth's history.

  20. An importance of diazotrophic cyanobacteria as a primary producer during Cretaceous Oceanic Anoxic Event 2

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    N. Ohkouchi

    2006-06-01

    Full Text Available In Livello Bonarelli black shale deposited during Cretaceous Oceanic Anoxic Event 2 (OAE-2, ca. 94 Ma, nitrogen isotopic compositions of bulk sediments are in a narrow range from −2.7 to −0.7. We also determined molecular distribution and nitrogen isotopic compositions of geoporphyrins extracted from the black shale. The nitrogen isotopic compositions of C32 Ni deoxophylloerythroetioporphyrin (DPEP and total Ni porphyrins are −3.5 and −3.3, respectively, leading us to the estimation that the mean nitrogen isotopic composition of photoautotrophic cell was around +1 during the formation of Bonarelli black shale. This value is suggestive of N2-fixation a dominant process for these photoautotrophs when assimilating nitrogen. Furthermore, Ni-chelated C32 DPEP, derived mainly from chlorophyll a was the highest concentration. Based on these evidence, we conclude that diazotrophic cyanobacteria were major primary producers during that time. The cyanobacteria may be key photoautotrophs during the formation of black shale type sediments intermittently observed throughout the later half of the Earth's history, and hence may have played a crucial role in the evolution of geochemical cycles.

  1. Isolation and purification of an axenic diazotrophic drought-tolerant cyanobacterium, Nostoc commune, from natural cyanobacterial crusts and its utilization for field research on soils polluted with radioisotopes.

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    Katoh, Hiroshi; Furukawa, Jun; Tomita-Yokotani, Kaori; Nishi, Yasuaki

    2012-08-01

    Nitrogen fixation and drought tolerance confer the ability to grow on dry land, and some terrestrial cyanobacteria exhibit these properties. These cyanobacteria were isolated in an axenic form from Nostoc commune clusters and other sources by modifying the method used to isolate the nitrogen-fixing and drought-tolerant cyanobacterium Nostoc sp. HK-01. Of these cyanobacteria, N. commune, which is difficult to isolate and purify, uses polysaccharides to maintain water, nitrogen fertilizers for nitrogen fixation, and can live in extreme environments because of desiccation tolerance. In this study, we examined the use of N. commune as biosoil for space agriculture and possible absorption of radioisotopes ((134)Cs, (137)Cs). This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.

  2. The Multiple Functions of Common Microbial Carbon Polymers, Glycogen and PHB, during Stress Responses in the Non-Diazotrophic Cyanobacterium Synechocystis sp. PCC 6803.

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    Damrow, Ramon; Maldener, Iris; Zilliges, Yvonne

    2016-01-01

    Classical microbial carbon polymers such as glycogen and polyhydroxybutyrate (PHB) have a crucial impact as both a sink and a reserve under macronutrient stress conditions. Most microbial species exclusively synthesize and degrade either glycogen or PHB. A few bacteria such as the phototrophic model organism Synechocystis sp. PCC 6803 surprisingly produce both physico-chemically different polymers under conditions of high C to N ratios. For the first time, the function and interrelation of both carbon polymers in non-diazotrophic cyanobacteria are analyzed in a comparative physiological study of single- and double-knockout mutants (ΔglgC; ΔphaC; ΔglgC/ΔphaC), respectively. Most of the observed phenotypes are explicitly related to the knockout of glycogen synthesis, highlighting the metabolic, energetic, and structural impact of this process whenever cells switch from an active, photosynthetic 'protein status' to a dormant 'glycogen status'. The carbon flux regulation into glycogen granules is apparently crucial for both phycobilisome degradation and thylakoid layer disassembly in the presence of light. In contrast, PHB synthesis is definitely not involved in this primary acclimation response. Moreover, the very weak interrelations between the two carbon-polymer syntheses indicate that the regulation and role of PHB synthesis in Synechocystis sp. PCC 6803 is different from glycogen synthesis.

  3. Proteome Analyses of Strains ATCC 51142 and PCC 7822 of the Diazotrophic Cyanobacterium Cyanothece sp under Culture Conditions Resulting in Enhanced H-2 Production

    Energy Technology Data Exchange (ETDEWEB)

    Aryal, Uma K.; Callister, Stephen J.; Mishra, Sujata; Zhang, Xiaohui; Shutthanandan, Janani I.; Angel, Thomas E.; Shukla, Anil K.; Monroe, Matthew E.; Moore, Ronald J.; Koppenaal, David W.; Smith, Richard D.; Sherman, Louis

    2013-02-01

    Cultures of the cyanobacterial genus Cyanothece have been shown to produce high levels of biohydrogen. These strains are diazotrophic and undergo pronounced diurnal cycles when grown under N2-fixing conditions in light-dark cycles. We seek to better understand the way in which proteins respond to these diurnal changes and we performed quantitative proteome analysis of Cyanothece ATCC 51142 and PCC 7822 grown under 8 different nutritional conditions. Nitrogenase expression was limited to N2-fixing conditions, and in the absence of glycerol, nitrogenase gene expression was linked to the dark period. However, glycerol induced expression of nitrogenase during part of the light period, together with cytochrome c oxidase (Cox), glycogen phosphorylase (Glp), and glycolytic and pentose-phosphate pathway (PPP) enzymes. This indicated that nitrogenase expression in the light was facilitated via higher respiration and glycogen breakdown. Key enzymes of the Calvin cycle were inhibited in Cyanothece ATCC 51142 in the presence of glycerol under H2 producing conditions, suggesting a competition between these sources of carbon. However, in Cyanothece PCC 7822, the Calvin cycle still played a role in cofactor recycling during H2 production. Our data comprise the first comprehensive profiling of proteome changes in Cyanothece PCC 7822, and allows an in-depth comparative analysis of major physiological and biochemical processes that influence H2-production in both the strains. Our results revealed many previously uncharacterized proteins that may play a role in nitrogenase activity and in other metabolic pathways and may provide suitable targets for genetic manipulation that would lead to improvement of large scale H2 production.

  4. Proteome Analyses of Strains ATCC 51142 and PCC 7822 of the Diazotrophic Cyanobacterium Cyanothece sp. under Culture Conditions Resulting in Enhanced H2 Production

    Science.gov (United States)

    Aryal, Uma K.; Callister, Stephen J.; Mishra, Sujata; Zhang, Xiaohui; Shutthanandan, Janani I.; Angel, Thomas E.; Shukla, Anil K.; Monroe, Matthew E.; Moore, Ronald J.; Koppenaal, David W.; Smith, Richard D.

    2013-01-01

    Cultures of the cyanobacterial genus Cyanothece have been shown to produce high levels of biohydrogen. These strains are diazotrophic and undergo pronounced diurnal cycles when grown under N2-fixing conditions in light-dark cycles. We seek to better understand the way in which proteins respond to these diurnal changes, and we performed quantitative proteome analysis of Cyanothece sp. strains ATCC 51142 and PCC 7822 grown under 8 different nutritional conditions. Nitrogenase expression was limited to N2-fixing conditions, and in the absence of glycerol, nitrogenase gene expression was linked to the dark period. However, glycerol induced expression of nitrogenase during part of the light period, together with cytochrome c oxidase (Cox), glycogen phosphorylase (Glp), and glycolytic and pentose phosphate pathway (PPP) enzymes. This indicated that nitrogenase expression in the light was facilitated via higher levels of respiration and glycogen breakdown. Key enzymes of the Calvin cycle were inhibited in Cyanothece ATCC 51142 in the presence of glycerol under H2-producing conditions, suggesting a competition between these sources of carbon. However, in Cyanothece PCC 7822, the Calvin cycle still played a role in cofactor recycling during H2 production. Our data comprise the first comprehensive profiling of proteome changes in Cyanothece PCC 7822 and allow an in-depth comparative analysis of major physiological and biochemical processes that influence H2 production in both strains. Our results revealed many previously uncharacterized proteins that may play a role in nitrogenase activity and in other metabolic pathways and may provide suitable targets for genetic manipulation that would lead to improvement of large-scale H2 production. PMID:23204418

  5. Towards long-read metagenomics: complete assembly of three novel genomes from bacteria dependent on a diazotrophic cyanobacterium in a freshwater lake co-culture.

    Science.gov (United States)

    Driscoll, Connor B; Otten, Timothy G; Brown, Nathan M; Dreher, Theo W

    2017-01-01

    Here we report three complete bacterial genome assemblies from a PacBio shotgun metagenome of a co-culture from Upper Klamath Lake, OR. Genome annotations and culture conditions indicate these bacteria are dependent on carbon and nitrogen fixation from the cyanobacterium Aphanizomenon flos-aquae, whose genome was assembled to draft-quality. Due to their taxonomic novelty relative to previously sequenced bacteria, we have temporarily designated these bacteria as incertae sedis Hyphomonadaceae strain UKL13-1 (3,501,508 bp and 56.12% GC), incertae sedis Betaproteobacterium strain UKL13-2 (3,387,087 bp and 54.98% GC), and incertae sedis Bacteroidetes strain UKL13-3 (3,236,529 bp and 37.33% GC). Each genome consists of a single circular chromosome with no identified plasmids. When compared with binned Illumina assemblies of the same three genomes, there was ~7% discrepancy in total genome length. Gaps where Illumina assemblies broke were often due to repetitive elements. Within these missing sequences were essential genes and genes associated with a variety of functional categories. Annotated gene content reveals that both Proteobacteria are aerobic anoxygenic phototrophs, with Betaproteobacterium UKL13-2 potentially capable of phototrophic oxidation of sulfur compounds. Both proteobacterial genomes contain transporters suggesting they are scavenging fixed nitrogen from A. flos-aquae in the form of ammonium. Bacteroidetes UKL13-3 has few completely annotated biosynthetic pathways, and has a comparatively higher proportion of unannotated genes. The genomes were detected in only a few other freshwater metagenomes, suggesting that these bacteria are not ubiquitous in freshwater systems. Our results indicate that long-read sequencing is a viable method for sequencing dominant members from low-diversity microbial communities, and should be considered for environmental metagenomics when conditions meet these requirements.

  6. Genomic structure of an economically important cyanobacterium, Arthrospira (Spirulina) platensis NIES-39.

    Science.gov (United States)

    Fujisawa, Takatomo; Narikawa, Rei; Okamoto, Shinobu; Ehira, Shigeki; Yoshimura, Hidehisa; Suzuki, Iwane; Masuda, Tatsuru; Mochimaru, Mari; Takaichi, Shinichi; Awai, Koichiro; Sekine, Mitsuo; Horikawa, Hiroshi; Yashiro, Isao; Omata, Seiha; Takarada, Hiromi; Katano, Yoko; Kosugi, Hiroki; Tanikawa, Satoshi; Ohmori, Kazuko; Sato, Naoki; Ikeuchi, Masahiko; Fujita, Nobuyuki; Ohmori, Masayuki

    2010-04-01

    A filamentous non-N(2)-fixing cyanobacterium, Arthrospira (Spirulina) platensis, is an important organism for industrial applications and as a food supply. Almost the complete genome of A. platensis NIES-39 was determined in this study. The genome structure of A. platensis is estimated to be a single, circular chromosome of 6.8 Mb, based on optical mapping. Annotation of this 6.7 Mb sequence yielded 6630 protein-coding genes as well as two sets of rRNA genes and 40 tRNA genes. Of the protein-coding genes, 78% are similar to those of other organisms; the remaining 22% are currently unknown. A total 612 kb of the genome comprise group II introns, insertion sequences and some repetitive elements. Group I introns are located in a protein-coding region. Abundant restriction-modification systems were determined. Unique features in the gene composition were noted, particularly in a large number of genes for adenylate cyclase and haemolysin-like Ca(2+)-binding proteins and in chemotaxis proteins. Filament-specific genes were highlighted by comparative genomic analysis.

  7. Diurnal Rhythms Result in Significant Changes in the Cellular Protein Complement in the Cyanobacterium Cyanothece 51142

    Energy Technology Data Exchange (ETDEWEB)

    Stockel, Jana; Jacobs, Jon M.; Elvitigala, Thanura R.; Liberton, Michelle L.; Welsh, Eric A.; Polpitiya, Ashoka D.; Gritsenko, Marina A.; Nicora, Carrie D.; Koppenaal, David W.; Smith, Richard D.; Pakrasi, Himadri B.

    2011-02-22

    Cyanothece sp. ATCC 51142 is a diazotrophic cyanobacterium notable for its ability to perform oxygenic photosynthesis and dinitrogen fixation in the same single cell. Previous transcriptional analysis revealed that the existence of these incompatible cellular processes largely depends on tightly synchronized expression programs involving ,30% of genes in the genome. To expand upon current knowledge, we have utilized sensitive proteomic approaches to examine the impact of diurnal rhythms on the protein complement in Cyanothece 51142. We found that 250 proteins accounting for,5% of the predicted ORFs from the Cyanothece 51142 genome and 20% of proteins detected under alternating light/dark conditions exhibited periodic oscillations in their abundances. Our results suggest that altered enzyme activities at different phases during the diurnal cycle can be attributed to changes in the abundance of related proteins and key compounds. The integration of global proteomics and transcriptomic data further revealed that post-transcriptional events are important for temporal regulation of processes such as photosynthesis in Cyanothece 51142. This analysis is the first comprehensive report on global quantitative proteomics in a unicellular diazotrophic cyanobacterium and uncovers novel findings about diurnal rhythms.

  8. Diurnal Rhythms Result in Significant Changes in the Cellular Protein Complement in the Cyanobacterium Cyanothece 51142

    Science.gov (United States)

    Elvitigala, Thanura R.; Liberton, Michelle; Welsh, Eric A.; Polpitiya, Ashoka D.; Gritsenko, Marina A.; Nicora, Carrie D.; Koppenaal, David W.; Smith, Richard D.; Pakrasi, Himadri B.

    2011-01-01

    Cyanothece sp. ATCC 51142 is a diazotrophic cyanobacterium notable for its ability to perform oxygenic photosynthesis and dinitrogen fixation in the same single cell. Previous transcriptional analysis revealed that the existence of these incompatible cellular processes largely depends on tightly synchronized expression programs involving ∼30% of genes in the genome. To expand upon current knowledge, we have utilized sensitive proteomic approaches to examine the impact of diurnal rhythms on the protein complement in Cyanothece 51142. We found that 250 proteins accounting for ∼5% of the predicted ORFs from the Cyanothece 51142 genome and 20% of proteins detected under alternating light/dark conditions exhibited periodic oscillations in their abundances. Our results suggest that altered enzyme activities at different phases during the diurnal cycle can be attributed to changes in the abundance of related proteins and key compounds. The integration of global proteomics and transcriptomic data further revealed that post-transcriptional events are important for temporal regulation of processes such as photosynthesis in Cyanothece 51142. This analysis is the first comprehensive report on global quantitative proteomics in a unicellular diazotrophic cyanobacterium and uncovers novel findings about diurnal rhythms. PMID:21364985

  9. Diurnal rhythms result in significant changes in the cellular protein complement in the cyanobacterium Cyanothece 51142.

    Directory of Open Access Journals (Sweden)

    Jana Stöckel

    Full Text Available Cyanothece sp. ATCC 51142 is a diazotrophic cyanobacterium notable for its ability to perform oxygenic photosynthesis and dinitrogen fixation in the same single cell. Previous transcriptional analysis revealed that the existence of these incompatible cellular processes largely depends on tightly synchronized expression programs involving ∼30% of genes in the genome. To expand upon current knowledge, we have utilized sensitive proteomic approaches to examine the impact of diurnal rhythms on the protein complement in Cyanothece 51142. We found that 250 proteins accounting for ∼5% of the predicted ORFs from the Cyanothece 51142 genome and 20% of proteins detected under alternating light/dark conditions exhibited periodic oscillations in their abundances. Our results suggest that altered enzyme activities at different phases during the diurnal cycle can be attributed to changes in the abundance of related proteins and key compounds. The integration of global proteomics and transcriptomic data further revealed that post-transcriptional events are important for temporal regulation of processes such as photosynthesis in Cyanothece 51142. This analysis is the first comprehensive report on global quantitative proteomics in a unicellular diazotrophic cyanobacterium and uncovers novel findings about diurnal rhythms.

  10. Diurnal rhythms result in significant changes in the cellular protein complement in the cyanobacterium Cyanothece 51142.

    Science.gov (United States)

    Stöckel, Jana; Jacobs, Jon M; Elvitigala, Thanura R; Liberton, Michelle; Welsh, Eric A; Polpitiya, Ashoka D; Gritsenko, Marina A; Nicora, Carrie D; Koppenaal, David W; Smith, Richard D; Pakrasi, Himadri B

    2011-02-22

    Cyanothece sp. ATCC 51142 is a diazotrophic cyanobacterium notable for its ability to perform oxygenic photosynthesis and dinitrogen fixation in the same single cell. Previous transcriptional analysis revealed that the existence of these incompatible cellular processes largely depends on tightly synchronized expression programs involving ∼30% of genes in the genome. To expand upon current knowledge, we have utilized sensitive proteomic approaches to examine the impact of diurnal rhythms on the protein complement in Cyanothece 51142. We found that 250 proteins accounting for ∼5% of the predicted ORFs from the Cyanothece 51142 genome and 20% of proteins detected under alternating light/dark conditions exhibited periodic oscillations in their abundances. Our results suggest that altered enzyme activities at different phases during the diurnal cycle can be attributed to changes in the abundance of related proteins and key compounds. The integration of global proteomics and transcriptomic data further revealed that post-transcriptional events are important for temporal regulation of processes such as photosynthesis in Cyanothece 51142. This analysis is the first comprehensive report on global quantitative proteomics in a unicellular diazotrophic cyanobacterium and uncovers novel findings about diurnal rhythms.

  11. The Green Berry Consortia of the Sippewissett Salt Marsh: Millimeter-Sized Aggregates of Diazotrophic Unicellular Cyanobacteria

    Directory of Open Access Journals (Sweden)

    Elizabeth G. Wilbanks

    2017-09-01

    Full Text Available Microbial interactions driving key biogeochemical fluxes often occur within multispecies consortia that form spatially heterogeneous microenvironments. Here, we describe the “green berry” consortia of the Sippewissett salt marsh (Falmouth, MA, United States: millimeter-sized aggregates dominated by an uncultured, diazotrophic unicellular cyanobacterium of the order Chroococcales (termed GB-CYN1. We show that GB-CYN1 is closely related to Crocosphaera watsonii (UCYN-B and “Candidatus Atelocyanobacterium thalassa” (UCYN-A, two groups of unicellular diazotrophic cyanobacteria that play an important role in marine primary production. Other green berry consortium members include pennate diatoms and putative heterotrophic bacteria from the Alphaproteobacteria and Bacteroidetes. Tight coupling was observed between photosynthetic oxygen production and heterotrophic respiration. When illuminated, the green berries became supersaturated with oxygen. From the metagenome, we observed that GB-CYN1 encodes photosystem II genes and thus has the metabolic potential for oxygen production unlike UCYN-A. In darkness, respiratory activity rapidly depleted oxygen creating anoxia within the aggregates. Metagenomic data revealed a suite of nitrogen fixation genes encoded by GB-CYN1, and nitrogenase activity was confirmed at the whole-aggregate level by acetylene reduction assays. Metagenome reads homologous to marker genes for denitrification were observed and suggest that heterotrophic denitrifiers might co-occur in the green berries, although the physiology and activity of facultative anaerobes in these aggregates remains uncharacterized. Nitrogen fixation in the surface ocean was long thought to be driven by filamentous cyanobacterial aggregates, though recent work has demonstrated the importance of unicellular diazotrophic cyanobacteria (UCYN from the order Chroococcales. The green berries serve as a useful contrast to studies of open ocean UCYN and may

  12. Importance of N2-Fixation on the Productivity at the North-Western Azores Current/Front System, and the Abundance of Diazotrophic Unicellular Cyanobacteria.

    Directory of Open Access Journals (Sweden)

    Virginie Riou

    Full Text Available To understand the impact of the northwestern Azores Current Front (NW-AzC/AzF system on HCO3--and N2-fixation activities and unicellular diazotrophic cyanobacteria (UCYN distribution, we combined geochemical and biological approaches from the oligotrophic surface to upper mesopelagic waters. N2-fixation was observed to sustain 45-85% of the HCO3--fixation in the picoplanktonic fraction performing 47% of the total C-fixation at the deep chlorophyll maximum north and south of the AzF. N2-fixation rates as high as 10.9 μmol N m-3 d-1 and surface nitrate δ15N as low as 2.7‰ were found in the warm (18-24°C, most saline (36.5-37.0 and least productive waters south of the AzF, where UCYN were the least abundant. However, picoplanktonic UCYN abundances up to 55 cells mL-1 were found at 45-200m depths in the coolest nutrient-rich waters north of the AzF. In this area, N2-fixation rates up to 4.5 μmol N m-3 d-1 were detected, associated with depth-integrated H13CO3--fixation rates at least 50% higher than observed south of the AzF. The numerous eddies generated at the NW-AzC/AzF seem to enhance exchanges of plankton between water masses, as well as vertical and horizontal diapycnal diffusion of nutrients, whose increase probably enhances the growth of diazotrophs and the productivity of C-fixers.

  13. Draft Genome Assembly of a Filamentous Euendolithic (True Boring) Cyanobacterium, Mastigocoleus testarum Strain BC008.

    Science.gov (United States)

    Guida, Brandon S; Garcia-Pichel, Ferran

    2016-01-28

    Mastigocoleus testarum strain BC008 is a model organism used to study marine photoautotrophic carbonate dissolution. It is a multicellular, filamentous, diazotrophic, euendolithic cyanobacterium ubiquitously found in marine benthic environments. We present an accurate draft genome assembly of 172 contigs spanning 12,700,239 bp with 9,131 annotated genes with an average G+C% of 37.3.

  14. Insights into the Physiology and Ecology of the Brackish-Water-Adapted Cyanobacterium

    NARCIS (Netherlands)

    Voss, B.; Bolhuis, H.; Fewer, D.P.; Kopf, M.; Möke, F.; Haas, F.; El-Shehawy, R.; Hayes, P.; Bergman, B.; Sivonen, K.; Dittmann, E.; Scanlan, D.J.; Hagemann, M.; Stal, L.J.; Hess, W.R.

    2013-01-01

    Nodularia spumigena is a filamentous diazotrophic cyanobacterium that dominates the annual late summer cyanobacterial blooms in the Baltic Sea. But N. spumigena also is common in brackish water bodies worldwide, suggesting special adaptation allowing it to thrive at moderate salinities. A draft geno

  15. Construction of ammonium-tolerant strains of diazotroph associated with rice and its applications

    Institute of Scientific and Technical Information of China (English)

    CHENGQi; SONGWei; YOUChongbiao

    1992-01-01

    In rice field, especially in the fertilized field the combined nitrogen content is rather high. It is well known that the nitrogen compounds, particularly NH4+ inhibits the nitrogenase activity- of diazotrophs. So, the enhancement of nitrogen fixation ability of diazotrophs in the presence of ammonia by means of genetic manipulation will be of importance for agricultural use.

  16. Cellular and functional specificity among ferritin-like proteins in the multicellular cyanobacterium Nostoc punctiforme.

    Science.gov (United States)

    Ekman, Martin; Sandh, Gustaf; Nenninger, Anja; Oliveira, Paulo; Stensjö, Karin

    2014-03-01

    Ferritin-like proteins constitute a remarkably heterogeneous protein family, including ferritins, bacterioferritins and Dps proteins. The genome of the filamentous heterocyst-forming cyanobacterium Nostoc punctiforme encodes five ferritin-like proteins. In the present paper, we report a multidimensional characterization of these proteins. Our phylogenetic and bioinformatics analyses suggest both structural and physiological differences among the ferritin-like proteins. The expression of these five genes responded differently to hydrogen peroxide treatment, with a significantly higher rise in transcript level for Npun_F3730 as compared with the other four genes. A specific role for Npun_F3730 in the cells tolerance against hydrogen peroxide was also supported by the inactivation of Npun_F3730, Npun_R5701 and Npun_R6212; among these, only the ΔNpun_F3730 strain showed an increased sensitivity to hydrogen peroxide compared with wild type. Analysis of promoter-GFP reporter fusions of the ferritin-like genes indicated that Npun_F3730 and Npun_R5701 were expressed in all cell types of a diazotrophic culture, while Npun_F6212 was expressed specifically in heterocysts. Our study provides the first comprehensive analysis combining functional differentiation and cellular specificity within this important group of proteins in a multicellular cyanobacterium. © 2013 John Wiley & Sons Ltd and Society for Applied Microbiology.

  17. The freshwater cyanobacterium Anabaena doliolum transformed with ApGSMT-DMT exhibited enhanced salt tolerance and protection to nitrogenase activity, but became halophilic.

    Science.gov (United States)

    Singh, Meenakshi; Sharma, Naveen K; Prasad, Shyam Babu; Yadav, Suresh Singh; Narayan, Gopeshwar; Rai, Ashwani K

    2013-03-01

    Glycine betaine (GB) is an important osmolyte synthesized in response to different abiotic stresses, including salinity. The two known pathways of GB synthesis involve: 1) two step oxidation of choline (choline → betaine aldehyde → GB), generally found in plants, microbes and animals; and 2) three step methylation of glycine (glycine → sarcosine → dimethylglycine → GB), mainly found in halophilic archaea, sulphur bacteria and the cyanobacterium Aphanothece (Ap.) halophytica. Here, we transformed a salt-sensitive freshwater diazotrophic filamentous cyanobacterium Anabaena (An.) doliolum with N-methyltransferase genes (ApGSMT-DMT) from Ap. halophytica using the triparental conjugation method. The transformed An. doliolum synthesized and accumulated GB in cells, and showed increased salt tolerance and protection to nitrogenase activity. The salt responsiveness of the transformant was also apparent as GB synthesis increased with increasing concentrations of NaCl in the nutrient solution, and maximal [12.92 µmol (g dry weight)(-1)] in cells growing at 0.5 M NaCl. Therefore, the transformed cyanobacterium has changed its behaviour from preferring freshwater to halophily. This study may have important biotechnological implications for the development of stress tolerant nitrogen-fixing cyanobacteria as biofertilizers for sustainable agriculture.

  18. The shifts of diazotrophic communities in spring and summer associated with coral Galaxea astreata, Pavona decussata and Porites lutea

    Directory of Open Access Journals (Sweden)

    Yanying Zhang

    2016-11-01

    Full Text Available The coral holobiont often resides in oligotrophic waters; both coral cells and their symbiotic dinoflagellates possess ammonium assimilation enzymes and potentially benefit from the nitrogen fixation of coral-associated diazotrophs. However, the seasonal dynamics of coral-associated diazotrophs are not well characterized. Here, the seasonal variations of diazotrophic communities associated with three corals, Galaxea astreata, Pavona decussata and Porites lutea, were studied using nifH gene amplicon pyrosequencing techniques. Our results revealed a great diversity of coral-associated diazotrophs. nifH sequences related to Alphaproteobacteria, Deltaproteobacteria and Gammaproteobacteria were ubiquitous and dominant in all corals in two seasons. In contrast with the coral P. decussata, both G. astreata and P. lutea showed significant seasonal changes in the diazotrophic communities and nifH gene abundance. Variable diazotroph groups accounted for a range from 11% to 49% within individual coral samples. Most of the variable diazotrophic groups from P. decussata were species-specific, however, the majority of overlapping variable groups in G. astreata and P. lutea showed the same seasonal variation characteristics. Rhodopseudomonas palustris- and Gluconacetobacter diazotrophicus-affiliated sequences were relatively abundant in the summer, whereas a nifH sequence related to Halorhodospira halophila was relatively abundant in spring G. astreata and P. lutea. The seasonal variations of all diazotrophic communities were significantly correlated with the seasonal shifts of ammonium and nitrate, suggesting that diazotrophs play an important role in the nitrogen cycle of the coral holobiont.

  19. Diazotrophs-assisted phytoremediation of heavy metals: a novel approach.

    Science.gov (United States)

    Ullah, Abid; Mushtaq, Hafsa; Ali, Hazrat; Munis, Muhammad Farooq Hussain; Javed, Muhammad Tariq; Chaudhary, Hassan Javed

    2015-02-01

    Heavy metals, which have severe toxic effects on plants, animals, and human health, are serious pollutants of the modern world. Remediation of heavy metal pollution is utmost necessary. Among different approaches used for such remediation, phytoremediation is an emerging technology. Research is in progress to enhance the efficiency of this plant-based technology. In this regard, the role of rhizospheric and symbiotic microorganisms is important. It was assessed by enumeration of data from the current studies that efficiency of phytoremediation can be enhanced by assisting with diazotrophs. These bacteria are very beneficial because they bring metals to more bioavailable form by the processes of methylation, chelation, leaching, and redox reactions and the production of siderophores. Diazotrophs also posses growth-promoting traits including nitrogen fixation, phosphorous solubilization, phytohormones synthesis, siderophore production, and synthesis of ACC-deaminase which may facilitate plant growth and increase plant biomass, in turn facilitating phytoremediation technology. Thus, the aim of this review is to highlight the potential of diazotrophs in assisting phytoremediation of heavy metals in contaminated soils. The novel current assessment of literature suggests the winning combination of diazotroph with phytoremediation technology.

  20. Insights into the physiology and ecology of the brackish-water-adapted cyanobacterium Nodularia spumigena sp. CCY9414 based on a genome-transcriptome analysis

    NARCIS (Netherlands)

    Voß, B.; Bolhuis, H.; Fewer, D.; Kopf, M.; Möke, F.; Haas, F.; El-Shehawy, R.; Hayes, P.; Bergman, B.; Sivonen, K.; Dittmann, E.; Scanlan, D.J.; Hagemann, M.; Stal, L.J.; Hess, W.R.

    2013-01-01

    Nodularia spumigena is a filamentous diazotrophic cyanobacterium that dominates the annual late summer cyanobacterial blooms in the Baltic Sea. But N. spumigena also is common in brackish water bodies worldwide, suggesting special adaptation allowing it to thrive at moderate salinities. A draft geno

  1. Across-habitat comparison of diazotroph activity in the subarctic.

    Science.gov (United States)

    Rousk, Kathrin; Sorensen, Pernille L; Lett, Signe; Michelsen, Anders

    2015-05-01

    Nitrogen (N) fixation by N2-fixing bacteria (diazotrophs) is the primary N input to pristine ecosystems like boreal forests and subarctic and arctic tundra. However, the contribution by the various diazotrophs to habitat N2 fixation remains unclear. We present results from in situ assessments of N2 fixation of five diazotroph associations (with a legume, lichen, feather moss, Sphagnum moss and free-living) incorporating the ground cover of the associations in five typical habitats in the subarctic (wet and dry heath, polygon-heath, birch forest, mire). Further, we assessed the importance of soil and air temperature, as well as moisture conditions for N2 fixation. Across the growing season, the legume had the highest total as well as the highest fraction of N2 fixation rates at habitat level in the heaths (>85 % of habitat N2 fixation), whereas the free-living diazotrophs had the highest N2 fixation rates in the polygon heath (56 %), the lichen in the birch forest (87 %) and Sphagnum in the mire (100 %). The feather moss did not contribute more than 15 % to habitat N2 fixation in any of the habitats despite its high ground cover. Moisture content seemed to be a major driver of N2 fixation in the lichen, feather moss and free-living diazotrophs. Our results show that the range of N2 fixers found in pristine habitats contribute differently to habitat N2 fixation and that ground cover of the associates does not necessarily mirror contribution.

  2. Effects of Selected Diazotrophs on Maize Growth

    Science.gov (United States)

    Kifle, Medhin H.; Laing, Mark D.

    2016-01-01

    Laboratory, greenhouse, and field experiments were conducted at the University of KwaZulu-Natal, Pietermaritzburg, South Africa in the 2010/2011 and 2011∖2012 seasons to study the effects of eight strains of diazotrophic bacteria on the growth and yield of maize. Maize seeds were treated with Bacillus megaterium (V16), Pseudomonas sp. (StB5, A3, A6, and A61), Burkholderia ambifaria (V9), Enterobacter cloacae (L1) and Pantoea ananatis (LB5), aiming to stimulate plant growth, and maintain or increase yields while reducing the need for N fertilization. All the diazotrophic bacteria increased germination of maize seed, and Pseudomonas sp. (StB5) and B. megaterium (V16) significantly increased shoot length. Pseudomonas sp. (StB5), B. megaterium (V16), E. cloacae (L1), B. ambifaria (V9), and Pseudomonas sp. (A3) very significantly increased root length and seed vigor index. Under greenhouse conditions, plants treated with diazotrophic bacteria developed more leaf chlorophyll and greater dry weight, albeit not significantly (n.s.). In a field trial in 2010/2011, application of the best five diazotrophic bacteria, with or without 33% N-fertilizer, had no significant effect on germination, grain yield, dry weight, plant height and leaf chlorophyll. In the 2011/2012 growing season, at 60 days after planting (DAP), all the diazotrophic bacteria increased plant dry weights to equal that of the fertilized control (33%N-fertilizer) (n.s.). After inoculation with the diazotrophs alone increased plant heights (n.s.), and chlorophyll contents (n.s.). With the addition of 33%N-fertilizer at planting, the diazotrophs still caused increases of chlorophyll content relative to the control with 33%N (n.s.). It may be concluded that the tested diazotrophs alone may be beneficial for use on maize growth. PMID:27713756

  3. EFFECTS OF SELECTED DIAZOTROPHS ON MAIZE GROWTH

    Directory of Open Access Journals (Sweden)

    Medhin Hadish Kifle

    2016-09-01

    Full Text Available Laboratory, greenhouse, and field experiments were conducted at the University of KwaZulu-Natal, Pietermaritzburg, South Africa in the 2010 2011 and 2011 2012 seasons to study the effects of eight strains of diazotrophic bacteria on the growth and yield of maize. Maize seeds were treated with Bacillus megaterium (V16, Pseudomonas sp. (StB5, A3, A6, and A61, Burkholderia ambifaria (V9, Enterobacter cloacae (L1 and Pantoea ananatis (LB5, aiming to stimulate plant growth, and maintain or increase yields while reducing the need for N fertilization. All the diazotrophic bacteria increased germination of maize seed, and Pseudomonas sp. (StB5 and B. megaterium (V16 significantly increased shoot length. Pseudomonas sp. (StB5, B. megaterium (V16, E. cloacae (L1, B. ambifaria (V9 and Pseudomonas sp. (A3 very significantly increased root length and seed vigor index. Under greenhouse conditions, plants treated with diazotrophic bacteria developed more leaf chlorophyll and greater dry weight, albeit not significantly (n.s.. In a field trial in 2010/2011, application of the best five diazotrophic bacteria, with or without 33% N-fertilizer, had no significant effect on germination, grain yield, dry weight, plant height and leaf chlorophyll. In the 2011/2012 growing season, at 60 days after planting (DAP, all the diazotrophic bacteria increased plant dry weights to equal that of the fertilized control (33%N-fertilizer(n.s.. After inoculation with the diazotrophs alone increased plant heights (n.s., and chlorophyll contents (n.s.. With the addition of 33%N-fertilizer at planting, the diazotrophs still caused increases of chlorophyll content relative to the control with 33%N (n.s.. It may be concluded that the tested diazotrophs alone may be beneficial for use on maize growth.

  4. Competition and facilitation between the marine nitrogen-fixing cyanobacterium Cyanothece and its associated bacterial community.

    Science.gov (United States)

    Brauer, Verena S; Stomp, Maayke; Bouvier, Thierry; Fouilland, Eric; Leboulanger, Christophe; Confurius-Guns, Veronique; Weissing, Franz J; Stal, LucasJ; Huisman, Jef

    2014-01-01

    N2-fixing cyanobacteria represent a major source of new nitrogen and carbon for marine microbial communities, but little is known about their ecological interactions with associated microbiota. In this study we investigated the interactions between the unicellular N2-fixing cyanobacterium Cyanothece sp. Miami BG043511 and its associated free-living chemotrophic bacteria at different concentrations of nitrate and dissolved organic carbon and different temperatures. High temperature strongly stimulated the growth of Cyanothece, but had less effect on the growth and community composition of the chemotrophic bacteria. Conversely, nitrate and carbon addition did not significantly increase the abundance of Cyanothece, but strongly affected the abundance and species composition of the associated chemotrophic bacteria. In nitrate-free medium the associated bacterial community was co-dominated by the putative diazotroph Mesorhizobium and the putative aerobic anoxygenic phototroph Erythrobacter and after addition of organic carbon also by the Flavobacterium Muricauda. Addition of nitrate shifted the composition toward co-dominance by Erythrobacter and the Gammaproteobacterium Marinobacter. Our results indicate that Cyanothece modified the species composition of its associated bacteria through a combination of competition and facilitation. Furthermore, within the bacterial community, niche differentiation appeared to play an important role, contributing to the coexistence of a variety of different functional groups. An important implication of these findings is that changes in nitrogen and carbon availability due to, e.g., eutrophication and climate change are likely to have a major impact on the species composition of the bacterial community associated with N2-fixing cyanobacteria.

  5. Permanent draft genome of strain ESFC-1: ecological genomics of a newly discovered lineage of filamentous diazotrophic cyanobacteria.

    Science.gov (United States)

    Everroad, R Craig; Stuart, Rhona K; Bebout, Brad M; Detweiler, Angela M; Lee, Jackson Z; Woebken, Dagmar; Prufert-Bebout, Leslie; Pett-Ridge, Jennifer

    2016-01-01

    The nonheterocystous filamentous cyanobacterium, strain ESFC-1, is a recently described member of the order Oscillatoriales within the Cyanobacteria. ESFC-1 has been shown to be a major diazotroph in the intertidal microbial mat system at Elkhorn Slough, CA, USA. Based on phylogenetic analyses of the 16S RNA gene, ESFC-1 appears to belong to a unique, genus-level divergence; the draft genome sequence of this strain has now been determined. Here we report features of this genome as they relate to the ecological functions and capabilities of strain ESFC-1. The 5,632,035 bp genome sequence encodes 4914 protein-coding genes and 92 RNA genes. One striking feature of this cyanobacterium is the apparent lack of either uptake or bi-directional hydrogenases typically expected within a diazotroph. Additionally, a large genomic island is found that contains numerous low GC-content genes and genes related to extracellular polysaccharide production and cell wall synthesis and maintenance.

  6. A novel cohabitation between two diazotrophic cyanobacteria in the oligotrophic ocean.

    Science.gov (United States)

    Momper, Lily M; Reese, Brandi Kiel; Carvalho, Gustavo; Lee, Patrick; Webb, Eric A

    2015-04-01

    The cyanobacterial genus Trichodesmium is biogeochemically significant because of its dual role in nitrogen and carbon fixation in the oligotrophic ocean. Trichodesmium species form colonies that can be easily enriched from the water column and used for shipboard rate measurements to estimate their contribution to oceanic carbon and nitrogen budgets. During a July 2010 cruise near the Hawaiian Islands in the oligotrophic North Pacific Subtropical Gyre, a specific morphology of Trichodesmium puff-form colonies were examined under epifluorescent microscopy and found to harbor a colonial endobiont, morphologically identified as the heterocystous diazotrophic cyanobacterium Calothrix. Using unialgal enrichments obtained from this cruise, we show that these Calothrix-like heterocystous cyanobionts (hetDA for 'Trichodesmium-associated heterocystous diazotroph') fix nitrogen on a diurnal cycle (maximally in the middle of the light cycle with a detectable minimum in the dark). Gene sequencing of nifH from the enrichments revealed that this genus was likely not quantified using currently described quantitative PCR (qPCR) primers. Guided by the sequence from the isolate, new hetDA-specific primers were designed and subsequent qPCR of environmental samples detected this diazotroph from surface water to a depth of 150 m, reaching densities up to ∼ 9 × 10(3) l(-1). Based on phylogenetic relatedness of nifH and 16S rRNA gene sequences, it is predicted that the distribution of this cyanobiont is not limited to subtropical North Pacific but likely reaches to the South Pacific and Atlantic Oceans. Therefore, this previously unrecognized cohabitation, if it reaches beyond the oligotrophic North Pacific, could potentially influence Trichodesmium-derived nitrogen fixation budgets in the world ocean.

  7. The cyanobacterium Mastigocladus fulfills the nitrogen demand of a terrestrial hot spring microbial mat

    OpenAIRE

    Estrella Alcamán, María; Fernandez, Camila; Delgado, Antonio; Bergman, Birgitta; Díez, Beatriz

    2015-01-01

    Cyanobacteria from Subsection V (Stigonematales) are important components of microbial mats in non-acidic terrestrial hot springs. Despite their diazotrophic nature (N2 fixers), their impact on the nitrogen cycle in such extreme ecosystems remains unknown. Here, we surveyed the identity and activity of diazotrophic cyanobacteria in the neutral hot spring of Porcelana (Northern Patagonia, Chile) during 2009 and 2011–2013. We used 16S rRNA and the nifH gene to analyze the distribution and diver...

  8. Diversity of Nitrogenase Systems in Diazotrophs

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Nitrogenase is a metalloprotein complex that catalyses the reaction of biological nitrogen fixation. At least three genetically distinct nitrogenase systems have been confirmed in diazotrophs, namely Nif, Vnf, and Anf, in which the active-site central metals are Mo, V, and Fe, respectively. The present review summarizes progress on the genetic, structural, and functional investigations into the three nitrogenases and discusses the possibility of the existence of other novel nitrogenases.

  9. Inoculation of sugarcane with diazotrophic bacteria

    Directory of Open Access Journals (Sweden)

    Nivaldo Schultz

    2014-04-01

    Full Text Available The sugarcane industry, a strategic crop in Brazil, requires technological improvements in production efficiency to increase the crop energy balance. Among the various currently studied alternatives, inoculation with diazotrophic bacteria proved to be a technology with great potential. In this context, the efficiency of a mixture of bacterial inoculant was evaluated with regard to the agronomic performance and N nutrition of sugarcane. The experiment was carried out on an experimental field of Embrapa Agrobiologia, in Seropédica, Rio de Janeiro, using a randomized block, 2 × 3 factorial design (two varieties and three treatments with four replications, totaling 24 plots. The varieties RB867515 and RB72454 were tested in treatments consisting of: inoculation with diazotrophic bacteria, N-fertilized control with 120 kg ha-1 N and absolute control (no inoculation and no N fertilizer. The inoculum was composed of five strains of five diazotrophic species. The yield, dry matter accumulation, total N in the shoot dry matter and the contribution of N by biological fixation were evaluated, using the natural 15N abundance in non-inoculated sugarcane as reference. The bacterial inoculant increased the stalk yield of variety RB72454 similarly to fertilization with 120 kg ha-1 N in the harvests of plant-cane and first ratoon crops, however the contribution of biological N fixation was unchanged by inoculation, indicating that the benefits of the inoculant in sugarcane may have resulted from plant growth promotion.

  10. Diazotroph diversity in the sea ice, melt ponds and surface waters of the Eurasian Basin of the Central Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Mar Fernández-Méndez

    2016-11-01

    Full Text Available The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing towards a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77ºN. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed.

  11. Diazotroph Diversity in the Sea Ice, Melt Ponds, and Surface Waters of the Eurasian Basin of the Central Arctic Ocean

    Science.gov (United States)

    Fernández-Méndez, Mar; Turk-Kubo, Kendra A.; Buttigieg, Pier L.; Rapp, Josephine Z.; Krumpen, Thomas; Zehr, Jonathan P.; Boetius, Antje

    2016-01-01

    The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing toward a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77°N. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed. PMID:27933047

  12. Diazotroph Diversity in the Sea Ice, Melt Ponds, and Surface Waters of the Eurasian Basin of the Central Arctic Ocean.

    Science.gov (United States)

    Fernández-Méndez, Mar; Turk-Kubo, Kendra A; Buttigieg, Pier L; Rapp, Josephine Z; Krumpen, Thomas; Zehr, Jonathan P; Boetius, Antje

    2016-01-01

    The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing toward a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77°N. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed.

  13. Nitrogen signalling in plant interactions with associative and endophytic diazotrophic bacteria.

    Science.gov (United States)

    Carvalho, T L G; Balsemão-Pires, E; Saraiva, R M; Ferreira, P C G; Hemerly, A S

    2014-10-01

    Some beneficial plant-interacting bacteria can biologically fix N2 to plant-available ammonium. Biological nitrogen fixation (BNF) is an important source of nitrogen (N) input in agriculture and represents a promising substitute for chemical N fertilizers. Diazotrophic bacteria have the ability to develop different types of root associations with different plant species. Among the highest rates of BNF are those measured in legumes nodulated by endosymbionts, an already very well documented model of plant-diazotrophic bacterial association. However, it has also been shown that economically important crops, especially monocots, can obtain a substantial part of their N needs from BNF by interacting with associative and endophytic diazotrophic bacteria, that either live near the root surface or endophytically colonize intercellular spaces and vascular tissues of host plants. One of the best reported outcomes of this association is the promotion of plant growth by direct and indirect mechanisms. Besides fixing N, these bacteria can also produce plant growth hormones, and some species are reported to improve nutrient uptake and increase plant tolerance against biotic and abiotic stresses. Thus, this particular type of plant-bacteria association consists of a natural beneficial system to be explored; however, the regulatory mechanisms involved are still not clear. Plant N status might act as a key signal, regulating and integrating various metabolic processes that occur during association with diazotrophic bacteria. This review will focus on the recent progress in understanding plant association with associative and endophytic diazotrophic bacteria, particularly on the knowledge of the N networks involved in BNF and in the promotion of plant growth. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  14. Competition and facilitation between the marine nitrogen-fixing cyanobacterium Cyanothece and its associated bacterial community

    Science.gov (United States)

    Brauer, Verena S.; Stomp, Maayke; Bouvier, Thierry; Fouilland, Eric; Leboulanger, Christophe; Confurius-Guns, Veronique; Weissing, Franz J.; Stal, LucasJ.; Huisman, Jef

    2014-01-01

    N2-fixing cyanobacteria represent a major source of new nitrogen and carbon for marine microbial communities, but little is known about their ecological interactions with associated microbiota. In this study we investigated the interactions between the unicellular N2-fixing cyanobacterium Cyanothece sp. Miami BG043511 and its associated free-living chemotrophic bacteria at different concentrations of nitrate and dissolved organic carbon and different temperatures. High temperature strongly stimulated the growth of Cyanothece, but had less effect on the growth and community composition of the chemotrophic bacteria. Conversely, nitrate and carbon addition did not significantly increase the abundance of Cyanothece, but strongly affected the abundance and species composition of the associated chemotrophic bacteria. In nitrate-free medium the associated bacterial community was co-dominated by the putative diazotroph Mesorhizobium and the putative aerobic anoxygenic phototroph Erythrobacter and after addition of organic carbon also by the Flavobacterium Muricauda. Addition of nitrate shifted the composition toward co-dominance by Erythrobacter and the Gammaproteobacterium Marinobacter. Our results indicate that Cyanothece modified the species composition of its associated bacteria through a combination of competition and facilitation. Furthermore, within the bacterial community, niche differentiation appeared to play an important role, contributing to the coexistence of a variety of different functional groups. An important implication of these findings is that changes in nitrogen and carbon availability due to, e.g., eutrophication and climate change are likely to have a major impact on the species composition of the bacterial community associated with N2-fixing cyanobacteria. PMID:25642224

  15. Diazotrophic bacterial community variability in a subtropical deep reservoir is correlated with seasonal changes in nitrogen.

    Science.gov (United States)

    Wang, Lina; Yu, Zheng; Yang, Jun; Zhou, Jing

    2015-12-01

    Nitrogen-fixing microorganisms (diazotrophs) play important roles in aquatic biogeochemistry and ecosystem functioning. However, little is known about the spatiotemporal variation of diazotrophic microbial communities in deep subtropical reservoirs. In this study, denaturing gradient gel electrophoresis (DGGE), clone libraries, quantitative PCR, and quantitative reverse transcription (RT)-PCR were used together to examine the vertical and seasonal patterns of diazotrophic microbial communities based on nitrogenase (nifH) gene sequences in the Dongzhen Reservoir, China, across time (every 3 months for 1 year) and space (five different water depths). In general, the numbers of DGGE bands increased with water depth during the stratification seasons (spring, summer, and autumn), with the clone-library-based operational taxonomic unit (OTU) number and nifH gene diversity being highest in autumn (6 OTUs at depth 0 m; 15 OTUs at 33 m) and winter (12 OTUs at 0 m, 13 OTUs at 33 m) but decreasing drastically in spring (2 OTUs at 0 m, 3 OTUs at 33 m) and summer (3 OTUs at 0 m, 2 OTUs at 33 m). The nifH gene abundance was lowest in the water mixing season (winter average, 5.17 × 10(7) copies/L) but increased in the three other seasons (9.03 × 10(9) copies/L). Cyanobacteria (dominated by filamentous thermophilic cyanobacteria and Cylindrospermopsis raciborskii) were the most dominant diazotrophic group at all depths and seasons, while both alphaproteobacteria and gammaproteobacteria were co-dominant in the bottom waters in autumn and winter. The distinct seasonal and spatial patterns in diazotrophic communities were significantly related to total nitrogen (TN) and ammonium nitrogen (NH4-N) in the reservoir (P cyanobacteria blooms.

  16. Nitrate Assimilation Genes of the Marine Diazotrophic, Filamentous Cyanobacterium Trichodesmium sp. Strain WH9601

    OpenAIRE

    Wang, Qingfeng; Li, Hong; Post, Anton F.

    2000-01-01

    A 4.0-kb DNA fragment of Trichodesmium sp. strain WH9601 contained gene sequences encoding the nitrate reduction enzymes, nirA and narB. A third gene positioned between nirA and narB encodes a putative membrane protein with similarity to the nitrate permeases of Bacillus subtilis (NasA) and Emericella nidulans (CrnA). The gene was shown to functionally complement a ΔnasA mutant of B. subtilis and was assigned the name napA (nitrate permease). NapA was involved in both nitrate and nitrite upta...

  17. Energetics of cyanophage N-1 multiplication in the diazotrophic cyanobacterium Nostoc muscorum.

    Science.gov (United States)

    Singh, S; Bhatnagar, A; Kashyap, A K

    1994-01-01

    Cyanophage N-1 multiplication was investigated during the latent period of the virus, when 14CO2 fixation was inhibited whereas respiratory O2 uptake increased approximately 67% at 4 h after infection. A simultaneous decrease (70%) in the glycogen content of infected cells indicated its catabolic involvement. A chloramphenicol-sensitive rise in glucose-6-phosphate dehydrogenase activity as a result of N-1 infection partly explained the increase in aerobic respiration. The total ATP pool declined to 53% of the control while Ca(2+)-dependent ATPase activity also declined (25%). In contrast, Mg(2+)-dependent ATPase activity increased (80%) in comparison with uninfected cells. Results suggest that oxidative phosphorylation was more crucial in the control of cyanophage N-1 development than photophosphorylation under photoautotrophic growth conditions.

  18. Investigation of the links between heterocyst and biohydrogen production by diazotrophic cyanobacterium A. variabilis ATCC 29413.

    Science.gov (United States)

    Salleh, Siti Fatihah; Kamaruddin, Azlina; Uzir, Mohamad Hekarl; Karim, Khairiah Abd; Mohamed, Abdul Rahman

    2016-03-01

    This work investigates the effect of heterocyst toward biohydrogen production by A. variabilis. The heterocyst frequency was artificially promoted by adding an amino acid analog, in this case DL-7-azatryptophan into the growth medium. The frequency of heterocyst differentiation was found to be proportional to the concentration of azatryptophan (0-25 µM) in the medium. Conversely, the growth and nitrogenase activity were gradually suppressed. In addition, there was also a distinct shortening of the cells filaments and detachment of heterocyst from the vegetative cells. Analysis on the hydrogen production performance revealed that both the frequency and distribution of heterocyst in the filaments affected the rate of hydrogen production. The highest hydrogen production rate and yield (41 µmol H2 mg chl a(-1) h(-1) and 97 mL H2 mg chl a(-1), respectively) were achieved by cells previously grown in 15 µM of azatryptophan with 14.5 % of heterocyst frequency. The existence of more isolated heterocyst has been shown to cause a relative loss in nitrogenase activity thus lowering the hydrogen production rate.

  19. Database of diazotrophs in global ocean: abundances, biomass and nitrogen fixation rates

    Directory of Open Access Journals (Sweden)

    Y.-W. Luo

    2012-02-01

    Full Text Available Marine N2 fixing microorganisms, termed diazotrophs, are a key functional group in marine pelagic ecosystems. The biological fixation of dinitrogen (N2 to bioavailable nitrogen provides an important new source of nitrogen for pelagic marine ecosystems and influences primary productivity and organic matter export to the deep ocean. As one of a series of efforts to collect biomass and rates specific to different phytoplankton functional groups, we have constructed a database on diazotrophic organisms in the global pelagic upper ocean by compiling about 12 000 direct field measurements of cyanobacterial diazotroph abundances (based on microscopic cell counts or qPCR assays targeting the nifH genes and N2 fixation rates. Biomass conversion factors are estimated based on cell sizes to convert abundance data to diazotrophic biomass. The database is limited spatially, lacking large regions of the ocean especially in the Indian Ocean. The data are approximately log-normal distributed, and large variances exist in most sub-databases with non-zero values differing 5 to 8 orders of magnitude. Lower mean N2 fixation rate was found in the North Atlantic Ocean than the Pacific Ocean. Reporting the geometric mean and the range of one geometric standard error below and above the geometric mean, the pelagic N2 fixation rate in the global ocean is estimated to be 62 (53–73 Tg N yr−1 and the pelagic diazotrophic biomass in the global ocean is estimated to be 4.7 (2.3–9.6 Tg C from cell counts and to 89 (40–200 Tg C from nifH-based abundances. Uncertainties related to biomass conversion factors can change the estimate of geometric mean pelagic diazotrophic biomass in the global ocean by about ±70%. This evolving database can be used to study spatial and temporal distributions and variations of marine N2 fixation, to validate geochemical estimates and to parameterize

  20. Effects of long-term elevated CO2, warming, and prolonged drought on Pleurozium-associated diazotrophic activity and abundance

    Science.gov (United States)

    Dyrnum, Kristine; Priemé, Anders; Michelsen, Anders

    2014-05-01

    Nitrogen (N2) fixation is the primary natural influx of N to terrestrial ecosystems, and changes in N2 fixation may have consequences for primary productivity and thus ecosystem function. We studied the activity and abundance of diazotrophs associated with the feather moss Pleurozium schreberi in a temperate heathland, after seven years of global change manipulations, including elevated atmospheric CO2 (510 ppm), increased temperature (0.5-1.5 ° C), and prolonged pre-summer droughts (4-6 weeks /year). Acetylene reduction assay was carried out monthly to monitor N2 fixation rates throughout one year, while nif H copy abundance, serving as a diazotroph abundance estimate, was measured by quantitative polymerase chain reaction (q-PCR). Prolonged summer droughts significantly increased both N2 fixation and nif H copy abundance, contrasting previous studies that demonstrate a direct negative correlation between N2 fixation and water availability. A shift in the relative abundance of N2-fixing bacteria from the green, upper parts of the moss stem to the lower, brown parts was observed. This shift could make diazotrophs less sensitive to desiccation, enabling N2 fixation to be upheld for longer during drought and thus causing higher abundance. Increased temperature likewise had a positive effect on the diazotroph abundance, although this did not translate into increased activity. Possibly, warming protects diazotrophs during extreme cold events, while actual N2 fixation is limited by water, disregarding a rise in potential N2 fixation caused by higher abundance. Increased CO2 caused no significant diazotroph response. Our study showed that long-term increase in temperature and recurrent drought events cause higher diazotroph abundance in Pleurozium schreberi and thus enhance the potential N2 fixations rate. Furthermore, our results indicate that diazotrophs may alter colonization patterns and thereby actively remain in the moss fraction less likely affected by

  1. Carotenoid Biosynthesis in Calothrix sp. 336/3: Composition of Carotenoids on Full Medium, During Diazotrophic Growth and After Long-Term H2 Photoproduction.

    Science.gov (United States)

    Kosourov, Sergey; Murukesan, Gayathri; Jokela, Jouni; Allahverdiyeva, Yagut

    2016-11-01

    The carotenoid composition of the filamentous heterocystous N2-fixing cyanobacterium Calothrix sp. 336/3 was investigated under three conditions: in full medium (non-diazotrophic growth); in the absence of combined nitrogen (diazotrophic growth); and after long-term H2 photoproduction (diazotrophic medium and absence of nitrogen in the atmosphere). Anabaena sp. PCC 7120 and its ΔhupL mutant with disrupted uptake hydrogenase were used as reference strains. Analysis of identified carotenoids and enzymes involved in carotenogenesis showed the presence of three distinct biosynthetic pathways in Calothrix sp. 336/3. The first one is directed towards biosynthesis of myxoxanthophylls, such as myxol 2'-methylpentoside and 2-hydroxymyxol 2'-methylpentoside. The second pathway results in production of hydroxylated carotenoids, such as zeaxanthin, caloxanthin and nostoxanthin, and the last pathway is responsible for biosynthesis of echinenone and hydroxylated forms of ketocarotenoids, such as 3'-hydroxyechinenone and adonixanthin. We found that carotenogenesis in filamentous heterocystous cyanobacteria varies depending on the nitrogen status of the cultures, with significant accumulation of echinenone during diazotrophic growth at the expense of β-carotene. Under the severe N deficiency and high CO2 supply, which leads to efficient H2 photoproduction, cyanobacteria degrade echinenone and β-carotene, and accumulate glycosylated and hydroxylated carotenoids, such as myxol (or ketomyxol) 2'-methylpentosides, 3'-hydroxyechinenone and zeaxanthin. We suggest that the stability of the photosynthetic apparatus in Calothrix sp. 336/3 cells under N deficiency and high carbon conditions, which also appeared as the partial recovery of the pigment composition by the end of the long-term (∼1 month) H2 photoproduction process, might be mediated by a high content of hydroxycarotenoids.

  2. Distribution and activity of diazotrophs in the Eastern Equatorial Atlantic

    OpenAIRE

    Foster, Rachel A.; Subramaniam, Ajit; Jonathan P Zehr

    2009-01-01

    The gene abundance and gene expression of six diazotroph populations from the Eastern Equatorial Atlantic in June 2007 were examined using nifH gene quantitative polymerase chain reaction (q PCR) methods. Of all the diazotrophs, Trichodesmium spp. was the most abundant with the highest number of gene copies in the Gulf of Guinea. Trichodesmium also had the highest nitrogenase gene transcript abundance overall with the maximum in samples collected at the equator and in waters influenced by the...

  3. Incorporation of diazotrophic fixed N2 by mesozooplankton — Case studies in the southern Baltic Sea

    Science.gov (United States)

    Wannicke, Nicola; Korth, Frederike; Liskow, Iris; Voss, Maren

    2013-05-01

    During two simultaneous cruises in the Central Baltic Sea in July 2007 we applied a 15N tracer addition approach to assess the impact of cyanobacterial N2 fixation on mesozooplankton production in the Central Baltic Sea. We determined rates of diazotrophic 15N2 fixation, as well as uptake of diazotrophic derived 15N by mesozooplankton species. Diazotrophic 15N2 fixation rates were low representing pre-bloom situations. A first order estimate using a two source mixing model of natural δ15N-PON abundance revealed that diazotrophic fixed N contributed to 27 ± 8% to mesozooplankton biomass. Additionally, the application of stable isotope tracer showed that fixed 15N was detectable in the mesozooplankton fraction within 1 h after the onset of the incubation. On a daily basis, 5% up to 100% of newly fixed 15N and 14% of cyanobacteria standing stock were incorporated by mesozooplankton species in our experimental set-ups. By applying size fractionating experiments and the usage of different control treatments, we calculated that the majority of 15N transfer (67%) was mediated by the release of nitrogenous compounds and their channelling through the microbial loop towards the mesozooplankton community. Moreover, direct grazing on filamentous cyanobacteria accounted for 33% of gross 15N incorporation. Grazing in the experiments seemed to be largely influenced by cyanobacterial species dominating the community and by the abundance of Cladoceran species like Evadne. Overall, N2 fixing cyanobacteria are ecological more important as instantaneous sources of nitrogen for higher trophic levels of the Baltic Sea food web than previously assumed.

  4. Draft Genome Sequence of Microcystis aeruginosa CACIAM 03, a Cyanobacterium Isolated from an Amazonian Freshwater Environment

    Science.gov (United States)

    Castro, Wendel Oliveira; Lima, Alex Ranieri Jerônimo; Moraes, Pablo Henrique Gonçalves; Siqueira, Andrei Santos; Aguiar, Délia Cristina Figueira; Baraúna, Anna Rafaella Ferreira; Martins, Luisa Carício; Fuzii, Hellen Thais; de Lima, Clayton Pereira Silva; Vianez-Júnior, João Lídio Silva Gonçalves; Nunes, Márcio Roberto Teixeira; Dall'Agnol, Leonardo Teixeira

    2016-01-01

    Given its toxigenic potential, Microcystis aeruginosa is an important bloom-forming cyanobacterium. Here, we present a draft genome and annotation of the strain CACIAM 03, which was isolated from an Amazonian freshwater environment. PMID:27856592

  5. Transcriptional regulators ChlR and CnfR are essential for diazotrophic growth in nonheterocystous cyanobacteria.

    Science.gov (United States)

    Tsujimoto, Ryoma; Kamiya, Narumi; Fujita, Yuichi

    2014-05-06

    Leptolyngbya boryana (Plectonema boryanum) is a diazotrophic cyanobacterium lacking heterocysts. How nitrogen fixation is regulated in filamentous nonheterocystous cyanobacteria remains unclear. Here we describe a large 50-kb nitrogen fixation (nif) gene cluster in L. boryana containing 50 genes. This gene cluster contains 14 nif genes (nifBSUHDKVZT and nifPENXW), two genes encoding transcriptional regulators showing high similarity to ChlR (chlorophyll regulator) and PatB, three genes encoding ferredoxin, three genes encoding cytochrome oxidase subunits, and 28 genes encoding nif-related proteins and proteins with putative or unknown functions. Eleven mutants lacking one gene or a subset of genes were isolated. Five of them did not grow under diazotrophic conditions, including two mutants lacking the transcriptional regulators. Although the chlR homolog-lacking mutant showed a normal level of nitrogenase activity, various intermediates of chlorophyll biosynthesis were accumulated under micro-oxic conditions. The phenotype suggested that ChlR activates the expression of the genes responsible for anaerobic chlorophyll biosynthesis to support energy supply for nitrogen fixation. In another mutant lacking the patB homolog, no transcripts of any nif genes were detected under nitrogen fixation conditions, which was consistent with no activity. Constitutive expression of patB in a shuttle vector resulted in low but significant nitrogenase activity even under nitrate-replete conditions, suggesting that the PatB homolog is the master regulator of nitrogen fixation. We propose to rename the patB homolog as cnfR, after cyanobacterial nitrogen fixation regulator.

  6. Seeds inoculation with diazotrophic bacteria and nitrogen application in side-dressing and leaf in maize

    OpenAIRE

    Claudinei Kappes; Orivaldo Arf; Marcelo Valentini Arf; João Paulo Ferreira; Edjair Augusto Dal Bem; José Roberto Portugal; Rafael Gonçalves Vilela

    2013-01-01

    Considering the importance of nitrogen management and its biological fixation with diazotrophic bacteria, this study was carried out aiming to evaluate the agronomic performance of maize, in response to seed inoculation with Azospirillum brasilense and nitrogen application in side-dressing and leaf. The experiment was conducted in Selvíria, Mato Grosso of Sul State, Brazil, during the growing season 2010/2011, on a clayey Rhodic Haplustox (20º 20’ S and 51º 24’ W, with altitude of 340 m). Six...

  7. Use of cyanobacterial diazotrophic technology in rice agriculture

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, D.N.; Kumar, A.; Mishra, A.K. [Banaras Hindu Univ., Varanasi (India)

    1991-12-31

    Diazotrophic cyanobacteria are photoautotrophic organisms that require sunlight as a sole energy source for the fixation of carbon and nitrogen. Therefore, they have great potential as biofertilizers, and their use will decrease fuel demand for fertilizer production. The agronomic potential of heterocystous cyanobacteria, either free-living or in symbiotic association with water fern Azolla, has long been recognized. This has led to the development of small scale biotechnology involving the use of paddy soils with appropriate cyanobacterial strains as biofertilizers in rice culture, as has been reported from China, Egypt, Philippines, and India. Besides increasing soil fertility and sustaining rice yield, these forms are also reported to benefit rice seedlings by producing growth-promoting substances, the nature of which is said to resemble gibberellins. Whereas the incorporation of nif genes into the rice plants by using tissue culture and modern genetic tools remain one of the ambitious research goals, the use of cyanobacterial diazotrophic technology in rice agriculture offers an immediate or even long-term alternative to synthetic nitrogen fertilizers, particularly in developing countries and the world as a whole. However, one of the weaknesses in this technology is the heavy application of several toxic agrochemicals, especially herbicides, which are reported in most cases as inhibitors of cyanobacterial diazotrophic growth, and in some cases as mutagenic. Naturally, a successful biotechnology requires the selection of suitable diazotrophic strains, as biofertilizers, that could tolerate the field-dose concentrations of herbicides and secrete ammonia.

  8. Nitrogen isotopic evidence for a shift from nitrate- to diazotroph-fueled export production in VAHINE mesocosm experiments

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    A. N. Knapp

    2015-12-01

    Full Text Available In a shallow, coastal lagoon off the southwest coast of New Caledonia, large-volume (~ 50 m3 mesocosm experiments were undertaken to track the fate of newly fixed nitrogen (N. The mesocosms were intentionally fertilized with 0.8 μM dissolved inorganic phosphorus (DIP to stimulate diazotrophy. N isotopic evidence indicates that the dominant source of N fueling export production shifted from subsurface nitrate (NO3− assimilated prior to the start of the 23 day experiments to N2 fixation by the end of the experiments. While the δ15N of the sinking particulate N (PNsink flux changed during the experiments, the δ15N of the suspended PN (PNsusp and dissolved organic N (DON pools did not. This is consistent with previous observations that the δ15N of surface ocean N pools is less responsive than that of PNsink to changes in the dominant source of new N to surface waters. In spite of the absence of detectable NO3− in the mesocosms, the δ15N of PNsink indicated that NO3− continued to fuel a significant fraction of export production (20 to 60 % throughout the 23 day experiments, with N2 fixation dominating export after about two weeks. The low rates of primary productivity and export production during the first 14 days were primarily supported by NO3−, and phytoplankton abundance data suggest that export was driven by large diatoms sinking out of surface waters. Concurrent molecular and taxonomic studies indicate that the diazotroph community was dominated by diatom-diazotroph assemblages (DDAs at this time. However, these DDAs represented a minor fraction (2 fixation; they were thus not important for driving export production, either directly or indirectly. The unicellular cyanobacterial diazotroph, a Cyanothece-like UCYN-C, proliferated during the last phase of the experiments when N2 fixation, primary production, and the flux of PNsink increased significantly, and δ15N budgets reflected a predominantly diazotrophic source of N fueling

  9. Bacterial N2-fixation in mangrove ecosystems: insights from a diazotroph-mangrove interaction

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    Gabriela eAlfaro-Espinoza

    2015-05-01

    Full Text Available Mangrove forests are highly productive ecosystems but represent low nutrient environments. Nitrogen availability is one of the main factors limiting mangrove growth. Diazotrophs have been identified as key organisms that provide nitrogen to these environments. N2-fixation by such organisms was found to be higher in the mangrove roots than in surrounding rhizosphere. Moreover, previous studies showed that mangroves grew better in the presence of N2-fixers indicating a potentially mutualistic relationship. However, the molecular signals and mechanisms that govern these interactions are still poorly understood. Here we present novel insights in the interaction of a diazotroph with a mangrove species to improve our understanding of the molecular and ecophysiological relationship between these two organisms under controlled conditions. Our results showed that M. mangrovicola is a versatile organism capable of competing with other organisms to survive for long periods in mangrove soils. N2-fixation by this bacterium was up-regulated in the presence of mangrove roots, indicating a possible beneficial interaction. The increase in N2-fixation was limited to cells of the exponential growth phase suggesting that N2-fixation differs over the bacterial growth cycle. Bacterial transformants harboring a transcriptional nifH::gusA fusion showed that M. mangrovicola successfully colonized mangrove roots and simultaneously conducted N2-fixation. The colonization process was stimulated by the lack of an external carbon source suggesting a possible mutualistic relationship. M. mangrovicola represents an interesting genetically accessible diazotroph, which colonize mangrove roots and exhibit higher N2-fixation in the presence of mangrove roots. Consequently, we propose this microorganism as a tool to study molecular interactions between N2-fixers and mangrove plants and to better understand how changes in the environment could impact these important and relatively

  10. Bacterial N2-fixation in mangrove ecosystems: insights from a diazotroph-mangrove interaction.

    Science.gov (United States)

    Alfaro-Espinoza, Gabriela; Ullrich, Matthias S

    2015-01-01

    Mangrove forests are highly productive ecosystems but represent low nutrient environments. Nitrogen availability is one of the main factors limiting mangrove growth. Diazotrophs have been identified as key organisms that provide nitrogen to these environments. N2-fixation by such organisms was found to be higher in the mangrove roots than in surrounding rhizosphere. Moreover, previous studies showed that mangroves grew better in the presence of N2-fixers indicating a potentially mutualistic relationship. However, the molecular signals and mechanisms that govern these interactions are still poorly understood. Here we present novel insights in the interaction of a diazotroph with a mangrove species to improve our understanding of the molecular and ecophysiological relationship between these two organisms under controlled conditions. Our results showed that Marinobacterium mangrovicola is a versatile organism capable of competing with other organisms to survive for long periods in mangrove soils. N2-fixation by this bacterium was up-regulated in the presence of mangrove roots, indicating a possible beneficial interaction. The increase in N2-fixation was limited to cells of the exponential growth phase suggesting that N2-fixation differs over the bacterial growth cycle. Bacterial transformants harboring a transcriptional nifH::gusA fusion showed that M. mangrovicola successfully colonized mangrove roots and simultaneously conducted N2-fixation. The colonization process was stimulated by the lack of an external carbon source suggesting a possible mutualistic relationship. M. mangrovicola represents an interesting genetically accessible diazotroph, which colonize mangrove roots and exhibit higher N2-fixation in the presence of mangrove roots. Consequently, we propose this microorganism as a tool to study molecular interactions between N2-fixers and mangrove plants and to better understand how changes in the environment could impact these important and relatively unknown

  11. Database of diazotrophs in global ocean: abundance, biomass and nitrogen fixation rates

    Directory of Open Access Journals (Sweden)

    Y.-W. Luo

    2012-08-01

    Full Text Available Marine N2 fixing microorganisms, termed diazotrophs, are a key functional group in marine pelagic ecosystems. The biological fixation of dinitrogen (N2 to bioavailable nitrogen provides an important new source of nitrogen for pelagic marine ecosystems and influences primary productivity and organic matter export to the deep ocean. As one of a series of efforts to collect biomass and rates specific to different phytoplankton functional groups, we have constructed a database on diazotrophic organisms in the global pelagic upper ocean by compiling about 12 000 direct field measurements of cyanobacterial diazotroph abundances (based on microscopic cell counts or qPCR assays targeting the nifH genes and N2 fixation rates. Biomass conversion factors are estimated based on cell sizes to convert abundance data to diazotrophic biomass. The database is limited spatially, lacking large regions of the ocean especially in the Indian Ocean. The data are approximately log-normal distributed, and large variances exist in most sub-databases with non-zero values differing 5 to 8 orders of magnitude. Reporting the geometric mean and the range of one geometric standard error below and above the geometric mean, the pelagic N2 fixation rate in the global ocean is estimated to be 62 (52–73 Tg N yr−1 and the pelagic diazotrophic biomass in the global ocean is estimated to be 2.1 (1.4–3.1 Tg C from cell counts and to 89 (43–150 Tg C from nifH-based abundances. Reporting the arithmetic mean and one standard error instead, these three global estimates are 140 ± 9.2 Tg N yr−1, 18 ± 1.8 Tg C and 590 ± 70 Tg C, respectively. Uncertainties related to biomass conversion factors can change the estimate of geometric mean pelagic diazotrophic biomass in the global ocean by about ±70%. It was recently established that the most commonly applied method used to measure N2

  12. Identification of a cis-acting element in nitrogen fixation genes recognized by CnfR in the nonheterocystous nitrogen-fixing cyanobacterium Leptolyngbya boryana.

    Science.gov (United States)

    Tsujimoto, Ryoma; Kamiya, Narumi; Fujita, Yuichi

    2016-08-01

    The filamentous cyanobacterium Leptolyngbya boryana has the ability to fix nitrogen without any heterocysts under microoxic conditions. Previously, we identified the cnfR gene for a master transcriptional activator for nitrogen fixation (nif) genes in a 50-kb gene cluster containing nif and nif-related genes in L. boryana. We showed that CnfR activates the transcription of nif genes in response to low oxygen conditions, which allows the oxygen-vulnerable enzyme nitrogenase to function. However, the regulatory mechanism that underlies regulation by CnfR remains unknown. In this study, we identified a conserved cis-acting element that is recognized by CnfR. We established a reporter system in the non-diazotrophic cyanobacterium Synechocystis sp. PCC 6803 using luciferase genes (luxAB). Reporter analysis was performed with a series of truncated and modified upstream regulatory regions of nifB and nifP. The cis-element can be divided into nine motifs I-IX, and it is located 76 bp upstream of the transcriptional start sites of nifB and nifP. Six motifs of them are essential for transcriptional activation by CnfR. This cis-acting element is conserved in the upstream regions of nif genes in all diazotrophic cyanobacteria, including Anabaena and Cyanothece, thereby suggesting that the transcriptional regulation by CnfR is widespread in nitrogen-fixing cyanobacteria.

  13. Arsenate resistance in the unicellular marine diazotroph Crocosphaera watsonii

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    Sonya eDyhrman

    2011-10-01

    Full Text Available The toxic arsenate ion can behave as a phosphate analog, and this can result in arsenate toxicity especially in areas with elevated arsenate to phosphate ratios like the surface waters of the ocean gyres. In these systems, cellular arsenate resistance strategies would allow phytoplankton to ameliorate the effects of arsenate transport into the cell. Despite the potential coupling between arsenate and phosphate cycling in oligotrophic marine waters, relatively little is known about arsenate resistance in the nitrogen-fixing marine cyanobacteria that are key components of the microbial community in low nutrient systems. The unicellular diazotroph, Crocosphaera watsonii WH8501, was able to grow at reduced rates with arsenate additions up to 30 nM, and estimated arsenate to phosphate ratios of 6:1. The genome of strain WH8501 contains homologs for arsA, arsH, arsB and arsC, allowing for the reduction of arsenate to arsenite and the pumping of arsenite out of the cell. The short-term addition of arsenate to the growth medium had no effect on nitrogen fixation. However, arsenate addition did result in the up-regulation of the arsB gene with increasing arsenate concentrations, indicating the induction of the arsenate detoxification response. The arsB gene was also up-regulated by phosphorus stress in concert with a gene encoding the high-affinity phosphate binding protein pstS. Both genes were down-regulated when phosphate was re-fed to phosphorus-stressed cells. A field survey of surface water from the low phosphate western North Atlantic detected expression of C. watsonii arsB, suggestive of the potential importance of arsenate resistance strategies in this and perhaps other systems.

  14. Intriguing diversity among diazotrophic picoplankton along a Mediterranean transect: a dominance of rhizobia

    Science.gov (United States)

    Le Moal, M.; Collin, H.; Biegala, I. C.

    2011-03-01

    The Mediterranean Sea is one of the most oligotrophic marine areas on earth where nitrogen fixation has formally believed to play an important role in carbon and nitrogen fluxes. Although this view is under debate, the diazotrophs responsible for this activity have still not been investigated in the open sea. In this study, we characterised the surface distribution and species richness of unicellular and filamentous diazotrophs across the Mediterranean Sea by combining microscopic counts with size fractionated in situ hybridization (TSA-FISH), and 16S rDNA and nifH genes phylogenies. These genetic analyses were possible owing to the development of a new PCR protocol adapted to scarce microorganisms that can detect as few as 1 cell ml-1 in cultures. Low concentrations of diazotrophic cyanobacteria were detected and this community was dominated at 99.9% by picoplankton hybridized to the Nitro821 probe, specific for unicellular diazotrophic cyanobacteria (UCYN). Among filamentous cyanobacteria only 0.02 filament ml-1 of Richelia were detected in the eastern basin, while small (0.7-1.5 μm) and large (2.5-3.2 μm) Nitro821-targeted cells were recovered at all stations with a mean concentration of 3.5 cell ml-1. The affiliation of the small Nitro821-targeted cells to UCYN-A was confirmed by 16S and nifH phylogenies in the western Mediterranean Sea. In the central and the eastern Mediterranean Sea no 16S rDNA and nifH sequence from UCYN was obtained as cells concentration were close to, or below PCR detection limit. Bradyrhizobium sequences dominated nifH clone libraries from picoplanktonic size fractions. A few sequences of γ-proteobacteria were also detected in the central Mediterranean Sea. While low phosphate and iron concentrations could explain the absence of Trichodesmium sp., the factors that prevent the development of UCYN-B and C remain unknown. We also propose that the dominating picoplankters probably developed specific strategies, such as associations with

  15. Influence of elevated CO2 concentrations on cell division and nitrogen fixation rates in the bloom-forming cyanobacterium Nodularia spumigena

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    U. Riebesell

    2009-04-01

    Full Text Available The surface ocean currently absorbs about one-fourth of the CO2 emitted to the atmosphere from human activities. As this CO2 dissolves in seawater, it reacts with seawater to form carbonic acid, increasing ocean acidity and shifting the partitioning of inorganic carbon species towards increased CO2 at the expense of CO32− concentrations. While the decrease in [CO32−] and/or increase in [H+] has been found to adversely affect many calcifying organisms, some photosynthetic organisms appear to benefit from increasing [CO2]. Among these is the cyanobacterium Trichodesmium, a predominant diazotroph (nitrogen-fixing in large parts of the oligotrophic oceans, which responded with increased carbon and nitrogen fixation at elevated pCO2. With the mechanism underlying this CO2 stimulation still unknown, the question arises whether this is a common response of diazotrophic cyanobacteria. In this study we therefore investigate the physiological response of Nodularia spumigena, a heterocystous bloom-forming diazotroph of the Baltic Sea, to CO2-induced changes in seawater carbonate chemistry. N. spumigena reacted to seawater acidification/carbonation with reduced cell division rates and nitrogen fixation rates, accompanied by significant changes in carbon and phosphorus quota and elemental composition of the formed biomass. Possible explanations for the contrasting physiological responses of Nodularia compared to Trichodesmium may be found in the different ecological strategies of non-heterocystous (Trichodesmium and heterocystous (Nodularia cyanobacteria.

  16. Influence of elevated CO2 concentrations on cell division and nitrogen fixation rates in the bloom-forming cyanobacterium Nodularia spumigena

    Directory of Open Access Journals (Sweden)

    U. Riebesell

    2009-09-01

    Full Text Available The surface ocean absorbs large quantities of the CO2 emitted to the atmosphere from human activities. As this CO2 dissolves in seawater, it reacts to form carbonic acid. While this phenomenon, called ocean acidification, has been found to adversely affect many calcifying organisms, some photosynthetic organisms appear to benefit from increasing [CO2]. Among these is the cyanobacterium Trichodesmium, a predominant diazotroph (nitrogen-fixing in large parts of the oligotrophic oceans, which responded with increased carbon and nitrogen fixation at elevated pCO2. With the mechanism underlying this CO2 stimulation still unknown, the question arises whether this is a common response of diazotrophic cyanobacteria. In this study we therefore investigate the physiological response of Nodularia spumigena, a heterocystous bloom-forming diazotroph of the Baltic Sea, to CO2-induced changes in seawater carbonate chemistry. N. spumigena reacted to seawater acidification/carbonation with reduced cell division rates and nitrogen fixation rates, accompanied by significant changes in carbon and phosphorus quota and elemental composition of the formed biomass. Possible explanations for the contrasting physiological responses of Nodularia compared to Trichodesmium may be found in the different ecological strategies of non-heterocystous (Trichodesmium and heterocystous (Nodularia cyanobacteria.

  17. GROWTH AND CARBON CONTENT OF THREE DIFFERENT-SIZED DIAZOTROPHIC CYANOBACTERIA OBSERVED IN THE SUBTROPICAL NORTH PACIFIC(1).

    Science.gov (United States)

    Goebel, Nicole L; Edwards, Christopher A; Carter, Brandon J; Achilles, Katherine M; Zehr, Jonathan P

    2008-10-01

    To develop tools for modeling diazotrophic growth in the open ocean, we determined the maximum growth rate and carbon content for three diazotrophic cyanobacteria commonly observed at Station ALOHA (A Long-term Oligotrophic Habitat Assessment) in the subtropical North Pacific: filamentous nonheterocyst-forming Trichodesmium and unicellular Groups A and B. Growth-irradiance responses of Trichodesmium erythraeum Ehrenb. strain IMS101 and Crocosphaera watsonii J. Waterbury strain WH8501 were measured in the laboratory. No significant differences were detected between their fitted parameters (±CI) for maximum growth rate (0.51 ± 0.09 vs. 0.49 ± 0.17 d(-1) ), half-light saturation (73 ± 29 vs. 66 ± 37 μmol quanta · m(-2)  · s(-1) ), and photoinhibition (0 and 0.00043 ± 0.00087 [μmol quanta · m(-2)  · s(-1) ](-1) ). Maximum growth rates and carbon contents of Trichodesmium and Crocosphaera cultures conformed to published allometric relationships, demonstrating that these relationships apply to oceanic diazotrophic microorganisms. This agreement promoted the use of allometric models to approximate unknown parameters of maximum growth rate (0.77 d(-1) ) and carbon content (480 fg C · μm(-3) ) for the uncultivated, unicellular Group A cyanobacteria. The size of Group A was characterized from samples from the North Pacific Ocean using fluorescence-activated cell sorting and real-time quantitative PCR techniques. Knowledge of growth and carbon content properties of these organisms facilitates the incorporation of different types of cyanobacteria in modeling efforts aimed at assessing the relative importance of filamentous and unicellular diazotrophs to carbon and nitrogen cycling in the open ocean.

  18. Density and diversity of diazotrophic bacteria isolated from Amazonian soils using N-free semi-solid media

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    Krisle da Silva

    2011-10-01

    Full Text Available Non-symbiotic diazotrophic bacteria are amongst the most important functional groups of soil-dwelling microorganisms. These bacteria contribute to plant growth predominantly through biological N2 fixation. Here, we evaluated the density and diversity of non-symbiotic diazotrophic bacteria in soils taken from diverse land use systems (LUS in Amazonia using nitrogen-free media. A total of 30 soil samples were collected from the following LUS: pristine forest, young secondary forest, old secondary forest, agroforestry, agriculture and pasture. Bacterial density was evaluated by the most probable number (MPN method utilizing N-free semi-solid media with varied compositions (JNFb, NFb, LGI and Fam. Individual isolates were characterized by colony and cellular morphology as well as total protein profiles and nitrogenase activity. Isolate genotypes were determined by partial 16S rDNA sequences. No typical diazotrophic growth in the JNFb medium was observed. Bacterial densities in the NFb medium were higher in the agriculture and agroforestry soil samples. In LGI and Fam media, bacterial densities were highest in the pasture soil samples. Overall, 22 isolates with high phenotypic diversity were obtained. Eleven isolates exhibited nitrogenase activity. Sequences of 16S rDNA genes of 14 out of 19 isolates had similarities below 100 % with known nitrogen-fixing species. Isolates were identified as belonging to the Burkholderia, Enterobacter, Serratia, Klebsiella, and Bacillus genera. A higher number of isolates from pasture soil samples were isolated, with the majority of these belonging to the Burkholderia and Bacillus genera. Among the isolates, unknown sequences were obtained, possibly indicating new species. Taken together, these data demonstrate that Fam, NFb, and LGI semi-solid media allowed the growth of diazotrophic bacteria belonging to different phylogenetic lines.

  19. Genome-wide identification of microRNA and siRNA responsive to endophytic beneficial diazotrophic bacteria in maize.

    Science.gov (United States)

    Thiebaut, Flávia; Rojas, Cristian A; Grativol, Clícia; Motta, Mariana Romeiro; Vieira, Tauan; Regulski, Michael; Martienssen, Robert A; Farinelli, Laurent; Hemerly, Adriana S; Ferreira, Paulo C G

    2014-09-06

    Small RNA (sRNA) has been described as a regulator of gene expression. In order to understand the role of maize sRNA (Zea mays-hybrid UENF 506-8) during association with endophytic nitrogen-fixing bacteria, we analyzed the sRNA regulated by its association with two diazotrophic bacteria, Herbaspirillum seropedicae and Azospirillum brasilense. Deep sequencing analysis was done with RNA extracted from plants inoculated with H. seropedicae, allowing the identification of miRNA and siRNA. A total of 25 conserved miRNA families and 15 novel miRNAs were identified. A dynamic regulation in response to inoculation was also observed. A hypothetical model involving copper-miRNA is proposed, emphasizing the fact that the up-regulation of miR397, miR398, miR408 and miR528, which is followed by inhibition of their targets, can facilitate association with diazotrophic bacteria. Similar expression patterns were observed in samples inoculated with A. brasilense. Moreover, novel miRNA and siRNA were classified in the Transposable Elements (TE) database, and an enrichment of siRNA aligned with TE was observed in the inoculated samples. In addition, an increase in 24-nt siRNA mapping to genes was observed, which was correlated with an increase in methylation of the coding regions and a subsequent reduction in transcription. Our results show that maize has RNA-based silencing mechanisms that can trigger specific responses when plants interact with beneficial endophytic diazotrophic bacteria. Our findings suggest important roles for sRNA regulation in maize, and probably in other plants, during association with diazotrophic bacteria, emphasizing the up-regulation of Cu-miRNA.

  20. Diazotrophic bacteria isolated from wild rice Oryza glumaepatula (Poaceae) in the Brazilian Amazon

    OpenAIRE

    Fernandes Júnior,Paulo Ivan; Duarte Pereira, Gilmara Maria; Perin, Liamara; da Silva, Luana Mesquita; Cardoso Baraúna, Alexandre; Muniz Alves, Francilene; Ribeiro Passos, Samuel; Édson Zilli, Jerri

    2013-01-01

    The association of wild grasses with diazotrophic bacteria in Brazilian biomes is poorly understood. The isolation and characterization of bacteria associated with wild grasses can contribute to understand the diazotrophic ecology as well as to identify bacteria with biotechnological applications. In this study, we isolated and characterized diazotrophic bacterial isolates from Oryza glumaepatula collected in Cerrado and Forest areas of the Amazon in Roraima State, Brazil. Healthy O. glumepat...

  1. Performance of pineapple slips inoculated with diazotrophic phosphate-solubilizing bacteria and rock phosphate

    OpenAIRE

    Lílian Estrela Borges Baldotto; Marihus Altoé Baldotto; Fábio Lopes Olivares; Adriane Nunes de Souza

    2014-01-01

    Besides fixing N2, some diazotrophic bacteria or diazotrophs, also synthesize organic acids and are able to solubilize rock phosphates, increasing the availability of P for plants. The application of these bacteria to pineapple leaf axils in combination with rock phosphate could increase N and P availability for the crop, due to the bacterial activity of biological nitrogen fixation and phosphate solubilization. The objectives of this study were: (i) to select and characterize diazotrophs abl...

  2. Transfer of diazotroph-derived nitrogen towards non-diazotrophic planktonic communities: a comparative study between Trichodesmium erythraeum, Crocosphaera watsonii and Cyanothece sp.

    Science.gov (United States)

    Berthelot, Hugo; Bonnet, Sophie; Grosso, Olivier; Cornet, Véronique; Barani, Aude

    2016-07-01

    Biological dinitrogen (N2) fixation is the major source of new nitrogen (N) for the open ocean, and thus promotes marine productivity, in particular in the vast N-depleted regions of the surface ocean. Yet, the fate of the diazotroph-derived N (DDN) in marine ecosystems is poorly understood, and its transfer to auto- and heterotrophic surrounding plankton communities is rarely measured due to technical limitations. Moreover, the different diazotrophs involved in N2 fixation (Trichodesmium spp. vs. UCYN) exhibit distinct patterns of N2 fixation and inhabit different ecological niches, thus having potentially different fates in the marine food webs that remain to be explored. Here we used nanometer scale secondary ion mass spectrometry (nanoSIMS) coupled with 15N2 isotopic labelling and flow cytometry cell sorting to examine the DDN transfer to specific groups of natural phytoplankton and bacteria during artificially induced diazotroph blooms in New Caledonia (southwestern Pacific). The fate of the DDN was compared according to the three diazotrophs: the filamentous and colony-forming Trichodesmium erythraeum (IMS101), and the unicellular strains Crocosphaera watsonii WH8501 and Cyanothece ATCC51142. After 48 h, 7-17 % of the N2 fixed during the experiment was transferred to the dissolved pool and 6-12 % was transferred to non-diazotrophic plankton. The transfer was twice as high in the T. erythraeum bloom than in the C. watsonii and Cyanothece blooms, which shows that filamentous diazotrophs blooms are more efficient at promoting non-diazotrophic production in N-depleted areas. The amount of DDN released in the dissolved pool did not appear to be a good indicator of the DDN transfer efficiency towards the non-diazotrophic plankton. In contrast, the 15N-enrichment of the extracellular ammonium (NH4+) pool was a good indicator of the DDN transfer efficiency: it was significantly higher in the T. erythraeum than in unicellular diazotroph blooms, leading to a DDN

  3. Molecular diversity of diazotrophs in oligotrophic tropical seagrass bed communities.

    Science.gov (United States)

    Bagwell, Christopher E; Rocque, Jeannine R; Smith, Garriett W; Polson, Shawn W; Friez, Michael J; Longshore, John W; Lovell, Charles R

    2002-02-01

    Denaturing gradient gel electrophoresis (DGGE) was employed to resolve PCR-amplified nifH sequences from vegetated and unvegetated sediments from two oligotrophic seagrass bed sites on San Salvador Island, Bahamas, in order to assess diazotroph species composition. All DGGE profiles from these sites showed the same prominent bands. These bands were sequenced, yielding 67 different nifH sequences, which were used in phylogenetic reconstructions. Most sequences were from anaerobes, but some were affiliated with the alpha- and (gamma-+beta-) Proteobacteria. Several NifH sequences were nearly identical to those from Azospirillum brasilense and Vibrio diazotrophicus. These seagrass bed sediments support a diverse diazotroph assemblage that is, at least superficially, similar to that associated with an intertidal grass (Spartina alterniflora).

  4. Oscillating behavior of carbohydrate granule formation and dinitrogen fixation in the cyanobacterium Cyanothece sp. strain ATCC 51142

    Science.gov (United States)

    Schneegurt, M. A.; Sherman, D. M.; Nayar, S.; Sherman, L. A.; Mitchell, C. A. (Principal Investigator)

    1994-01-01

    It has been shown that some aerobic, unicellular, diazotrophic cyanobacteria temporally separate photosynthetic O2 evolution and oxygen-sensitive N2 fixation. Cyanothece sp. ATCC strain 51142 is an aerobic, unicellular, diazotrophic cyanobacterium that fixes N2 during discrete periods of its cell cycle. When the bacteria are maintained under diurnal light-dark cycles, N2 fixation occurs in the dark. Similar cycling is observed in continuous light, implicating a circadian rhythm. Under N2-fixing conditions, large inclusion granules form between the thylakoid membranes. Maximum granulation, as observed by electron microscopy, occurs before the onset of N2 fixation, and the granules decrease in number during the period of N2 fixation. The granules can be purified from cell homogenates by differential centrifugation. Biochemical analyses of the granules indicate that these structures are primarily carbohydrate, with some protein. Further analyses of the carbohydrate have shown that it is a glucose polymer with some characteristics of glycogen. It is proposed that N2 fixation is driven by energy and reducing power stored in these inclusion granules. Cyanothece sp. strain ATCC 51142 represents an excellent experimental organism for the study of the protective mechanisms of nitrogenase, metabolic events in cyanobacteria under normal and stress conditions, the partitioning of resources between growth and storage, and biological rhythms.

  5. High-yield production of extracellular type-I cellulose by the cyanobacterium Synechococcus sp. PCC 7002

    OpenAIRE

    Zhao, Chi; Li,Zhongkui; Li, Tao; Zhang, Yingjiao; Bryant, Donald A.; Zhao, Jindong

    2015-01-01

    Cellulose synthase, encoded by the cesA gene, is responsible for the synthesis of cellulose in nature. We show that the cell wall of the cyanobacterium Synechococcus sp. PCC 7002 naturally contains cellulose. Cellulose occurs as a possibly laminated layer between the inner and outer membrane, as well as being an important component of the extracellular glycocalyx in this cyanobacterium. Overexpression of six genes, cmc–ccp–cesAB–cesC–cesD–bgl, from Gluconacetobacter xylinus in Synechococcus s...

  6. Contribution and pathways of diazotroph-derived nitrogen to zooplankton during the VAHINE mesocosm experiment in the oligotrophic New Caledonia lagoon

    Science.gov (United States)

    Hunt, Brian P. V.; Bonnet, Sophie; Berthelot, Hugo; Conroy, Brandon J.; Foster, Rachel A.; Pagano, Marc

    2016-05-01

    In oligotrophic tropical and subtropical oceans, where strong stratification can limit the replenishment of surface nitrate, dinitrogen (N2) fixation by diazotrophs can represent a significant source of nitrogen (N) for primary production. The VAHINE (VAriability of vertical and tropHIc transfer of fixed N2 in the south-wEst Pacific) experiment was designed to examine the fate of diazotroph-derived nitrogen (DDN) in such ecosystems. In austral summer 2013, three large ( ˜ 50 m3) in situ mesocosms were deployed for 23 days in the New Caledonia lagoon, an ecosystem that typifies the low-nutrient, low-chlorophyll environment, to stimulate diazotroph production. The zooplankton component of the study aimed to measure the incorporation of DDN into zooplankton biomass, and assess the role of direct diazotroph grazing by zooplankton as a DDN uptake pathway. Inside the mesocosms, the diatom-diazotroph association (DDA) het-1 predominated during days 5-15 while the unicellular diazotrophic cyanobacteria UCYN-C predominated during days 15-23. A Trichodesmium bloom was observed in the lagoon (outside the mesocosms) towards the end of the experiment. The zooplankton community was dominated by copepods (63 % of total abundance) for the duration of the experiment. Using two-source N isotope mixing models we estimated a mean ˜ 28 % contribution of DDN to zooplankton nitrogen biomass at the start of the experiment, indicating that the natural summer peak of N2 fixation in the lagoon was already contributing significantly to the zooplankton. Stimulation of N2 fixation in the mesocosms corresponded with a generally low-level enhancement of DDN contribution to zooplankton nitrogen biomass, but with a peak of ˜ 73 % in mesocosm 1 following the UCYN-C bloom. qPCR analysis targeting four of the common diazotroph groups present in the mesocosms (Trichodesmium, het-1, het-2, UCYN-C) demonstrated that all four were ingested by copepod grazers, and that their abundance in copepod

  7. Solubilization of zinc compounds by the diazotrophic, plant growth promoting bacterium Gluconacetobacter diazotrophicus.

    Science.gov (United States)

    Saravanan, V S; Madhaiyan, M; Thangaraju, M

    2007-01-01

    Gluconacetobacter diazotrophicus an endophytic diazotroph also encountered as rhizosphere bacterium is reported to possess different plant growth promoting characteristics. In this study, we assessed the zinc solubilizing potential of G. diazotrophicus under in vitro conditions with different Zn compounds using glucose or sucrose as carbon sources. G. diazotrophicus showed variations in their solubilization potential with the strains used and the Zn compounds tested. G. diazotrophicus PAl5 efficiently solubilized the Zn compounds tested and ZnO was effectively solubilized than ZnCO(3) or Zn(3)(PO(4))(2). The soluble Zn concentration was determined in the culture supernatant through Atomic Absorption Spectrophotometer. Gas chromatography coupled Mass Spectrometry analysis revealed 5-ketogluconic acid, a derivative of gluconic acid as the major organic acid produced by G. diazotrophicus PAl5 cultured with glucose as carbon source. This organic anion may be an important agent that helped in the solubilization of insoluble Zn compounds.

  8. Increased Biomass of Nursery-Grown Douglas-Fir Seedlings upon Inoculation with Diazotrophic Endophytic Consortia

    Directory of Open Access Journals (Sweden)

    Zareen Khan

    2015-10-01

    Full Text Available Douglas-fir (Pseudotsuga menziesii seedlings are periodically challenged by biotic and abiotic stresses. The ability of endophytes to colonize the interior of plants could confer benefits to host plants that may play an important role in plant adaptation to environmental changes. In this greenhouse study, nursery-grown Douglas-fir seedlings were inoculated with diazotrophic endophytes previously isolated from poplar and willow trees and grown for fifteen months in nutrient-poor conditions. Inoculated seedlings had significant increases in biomass (48%, root length (13% and shoot height (16% compared to the control seedlings. Characterization of these endophytes for symbiotic traits in addition to nitrogen fixation revealed that they can also solubilize phosphate and produce siderophores. Colonization was observed through fluorescent microscopy in seedlings inoculated with gfp- and mkate-tagged strains. Inoculation with beneficial endophytes could prove to be valuable for increasing the production of planting stocks in forest nurseries.

  9. Isolation, characterization and localization of extracellular polymeric substances from the cyanobacterium Arthrospira platensis strain MMG-9

    NARCIS (Netherlands)

    Ahmed, M.; Moerdijk-Poortvliet, T.C.W.; Wijnholds, A.; Stal, L.J.; Hasnain, S.

    2014-01-01

    Arthrospira platensis is a cyanobacterium known for its nutritional value and secondary metabolites. Extracellular polymeric substances (EPS) are an important trait of most cyanobacteria, including A. platensis. Here, we extracted and analysed different fractions of EPS from a locally isolated strai

  10. Isolation, characterization and localization of extracellular polymeric substances from the cyanobacterium

    NARCIS (Netherlands)

    Ahmed, M.; Wijnholds, A.; Stal, L.J.; Hasnain, S.

    2014-01-01

    Arthrospira platensis is a cyanobacterium known for its nutritional value and secondary metabolites. Extracellular polymeric substances (EPS) are an important trait of most cyanobacteria, including A. platensis. Here, we extracted and analysed different fractions of EPS from a locally isolated strai

  11. Diazotrophic bacterioplankton in a coral reef lagoon: phylogeny, diel nitrogenase expression and response to phosphate enrichment.

    Science.gov (United States)

    Hewson, Ian; Moisander, Pia H; Morrison, Amanda E; Zehr, Jonathan P

    2007-05-01

    We investigated diazotrophic bacterioplankton assemblage composition in the Heron Reef lagoon (Great Barrier Reef, Australia) using culture-independent techniques targeting the nifH fragment of the nitrogenase gene. Seawater was collected at 3 h intervals over a period of 72 h (i.e. over diel as well as tidal cycles). An incubation experiment was also conducted to assess the impact of phosphate (PO(4)3*) availability on nifH expression patterns. DNA-based nifH libraries contained primarily sequences that were most similar to nifH from sediment, microbial mat and surface-associated microorganisms, with a few sequences that clustered with typical open ocean phylotypes. In contrast to genomic DNA sequences, libraries prepared from gene transcripts (mRNA amplified by reverse transcription-polymerase chain reaction) were entirely cyanobacterial and contained phylotypes similar to those observed in open ocean plankton. The abundance of Trichodesmium and two uncultured cyanobacterial phylotypes from previous studies (group A and group B) were studied by quantitative-polymerase chain reaction in the lagoon samples. These were detected as transcripts, but were not detected in genomic DNA. The gene transcript abundance of these phylotypes demonstrated variability over several diel cycles. The PO(4)3* enrichment experiment had a clearer pattern of gene expression over diel cycles than the lagoon sampling, however PO(4)3* additions did not result in enhanced transcript abundance relative to control incubations. The results suggest that a number of diazotrophs in bacterioplankton of the reef lagoon may originate from sediment, coral or beachrock surfaces, sloughing into plankton with the flooding tide. The presence of typical open ocean phylotype transcripts in lagoon bacterioplankton may indicate that they are an important component of the N cycle of the coral reef.

  12. Photoacclimation of cultured strains of the cyanobacterium

    NARCIS (Netherlands)

    Bañares-España, E.; Kromkamp, J.C.; López-Rodas, V.; Costas, E.; Flores-Moya, A.

    2013-01-01

    The cyanobacterium Microcystis aeruginosa forms blooms that can consist of colonies. We have investigated how M.aeruginosa acclimatizes to changing light conditions such as can occur during blooms. Three different strains were exposed to two irradiance levels: lower (LL) and higher (HL) than the

  13. Chlorophyll f-driven photosynthesis in a cavernous cyanobacterium.

    Science.gov (United States)

    Behrendt, Lars; Brejnrod, Asker; Schliep, Martin; Sørensen, Søren J; Larkum, Anthony W D; Kühl, Michael

    2015-09-01

    Chlorophyll (Chl) f is the most recently discovered chlorophyll and has only been found in cyanobacteria from wet environments. Although its structure and biophysical properties are resolved, the importance of Chl f as an accessory pigment in photosynthesis remains unresolved. We found Chl f in a cyanobacterium enriched from a cavernous environment and report the first example of Chl f-supported oxygenic photosynthesis in cyanobacteria from such habitats. Pigment extraction, hyperspectral microscopy and transmission electron microscopy demonstrated the presence of Chl a and f in unicellular cyanobacteria found in enrichment cultures. Amplicon sequencing indicated that all oxygenic phototrophs were related to KC1, a Chl f-containing cyanobacterium previously isolated from an aquatic environment. Microsensor measurements on aggregates demonstrated oxygenic photosynthesis at 742 nm and less efficient photosynthesis under 768- and 777-nm light probably because of diminished overlap with the absorption spectrum of Chl f and other far-red absorbing pigments. Our findings suggest the importance of Chl f-containing cyanobacteria in terrestrial habitats.

  14. Nitrogen isotopic evidence for a shift from nitrate- to diazotroph-fueled export production in the VAHINE mesocosm experiments

    Science.gov (United States)

    Knapp, Angela N.; Fawcett, Sarah E.; Martínez-Garcia, Alfredo; Leblond, Nathalie; Moutin, Thierry; Bonnet, Sophie

    2016-08-01

    In a coastal lagoon with a shallow, 25 m water column off the southwest coast of New Caledonia, large-volume ( ˜ 50 m3) mesocosm experiments were undertaken to track the fate of newly fixed nitrogen (N). The mesocosms were intentionally fertilized with 0.8 µM dissolved inorganic phosphorus to stimulate diazotrophy. N isotopic evidence indicates that the dominant source of N fueling export production shifted from subsurface nitrate (NO3-) assimilated prior to the start of the 23-day experiments to N2 fixation by the end of the experiments. While the δ15N of the sinking particulate N (PNsink) flux changed during the experiments, the δ15N of the suspended PN (PNsusp) and dissolved organic N (DON) pools did not. This is consistent with previous observations that the δ15N of surface ocean N pools is less responsive than that of PNsink to changes in the dominant source of new N to surface waters. In spite of the absence of detectable NO3- in the mesocosms, the δ15N of PNsink indicated that NO3- continued to fuel a significant fraction of export production (20 to 60 %) throughout the 23-day experiments, with N2 fixation dominating export after about 2 weeks. The low rates of organic N export during the first 14 days were largely supported by NO3-, and phytoplankton abundance data suggest that sinking material primarily comprised large diatoms. Concurrent molecular and taxonomic studies indicate that the diazotroph community was dominated by diatom-diazotroph assemblages (DDAs) at this time. However, these DDAs represented a minor fraction (< 5 %) of the total diatom community and contributed very little new N via N2 fixation; they were thus not important for driving export production, either directly or indirectly. The unicellular cyanobacterial diazotroph, a Cyanothece-like UCYN-C, proliferated during the last phase of the experiments when N2 fixation, primary production, and the flux of PNsink increased significantly, and δ15N budgets reflected a predominantly

  15. Intriguing diversity among diazotrophic picoplankton along a Mediterranean transect: from the origin of plastids to the dominance of rhizobia

    Science.gov (United States)

    Le Moal, M.; Collin, H.; Biegala, I. C.

    2010-12-01

    The Mediterranean Sea is one of the most oligotrophic marine areas on earth where nitrogen fixation has been formally believed to play an important role in carbon and nitrogen fluxes. Although this view is under debate, the diazotrophs responsible for this activity have still not been investigated in the open sea. In this study we characterised the surface distribution and species richness of unicellular and filamentous diazotrophs across the Mediterranean Sea by combining microscopic counts with size fractionated in situ hybridization (TSA-FISH), and 16S rDNA and nifH phylogenies. These genetic analyses were possible owning to the development of a new PCR protocol adapted for scarce microorganisms (0.2 cell ml-1). Low concentrations of diazotrophic cyanobacteria were detected and this community was dominated at 99.9% by picoplankton hybridized with Nitro821 probe, specific for unicellular diazotrophic cyanobacteria (UCYN). Among filamentous cyanobacteria only 0.02 filament ml-1 of Richelia were detected in the eastern basin, while small (0.7-1.5 μm) and large (2.5-3.2 μm) Nitro821-targeted cells were recovered at all stations and averaged 3.5 cell ml-1. The affiliation of the small Nitro821-targeted cells to UCYN-A was confirmed by 16S and nifH phylogenies in the western Mediterranean Sea. Surprisingly, the larger hybridized cells were not belonging to UCYN-B and C but to plastids of picoeukaryote. NifH gene was not recovered among picoeukaryotes, when rhizobia sequences, including the ones of Bradyrhizobia, were dominating nifH clone libraries from picoplanktonic size fractions. Few sequences of γ-proteobacteria were also detected in central Mediterranean Sea. While low phosphate and iron concentrations could explain the absence of Trichodesmium sp., the factors that prevent the development of UCYN-B and C remain unknown. We also propose that the dominating picoplankters probably developed specific strategies, such as associations with protists or particles

  16. Anthropogenic impact on diazotrophic diversity in the mangrove rhizosphere revealed by nifH pyrosequencing

    OpenAIRE

    2015-01-01

    Diazotrophs in the mangrove rhizosphere play a major role in providing new nitrogen to the mangrove ecosystem and their composition and activity are strongly influenced by anthropogenic activity and ecological conditions. In this study, the diversity of the diazotroph communities in the rhizosphere sediment of five tropical mangrove sites with different levels of pollution along the north and south coastline of Singapore were studied by pyrosequencing of the nifH gene. Bioinformatics analysis...

  17. Specificity of salt marsh diazotrophs for vegetation zones and plant hosts

    Directory of Open Access Journals (Sweden)

    Debra Aline Davis

    2012-03-01

    Full Text Available Salt marshes located on the east coast of temperate North America are highly productive, typically nitrogen-limited, and support diverse assemblages of nitrogen fixing (diazotrophic bacteria. The distributions of these diazotrophs are strongly influenced by plant host and abiotic environmental parameters. Crab Haul Creek Basin, North Inlet, SC, USA is a tidally dominated marsh that displays discrete plant zones distributed along an elevation gradient from the tidal creek bank to the terrestrial forest. These zones are defined by gradients of abiotic environmental variables, particularly salinity and sulfide. DGGE fingerprinting and phylogenetic analyses of recovered sequences demonstrated that the distributions of some diazotrophs indicate plant host specificity and that diazotroph assemblages across the marsh gradient are heavily influenced by edaphic conditions. Broadly distributed diazotrophs capable of maintaining populations in all environmental conditions across the gradient are also present in these assemblages. Parsimony test results confirm that diazotroph assemblages in different plant zones are significantly (p<0.01 different across the marsh landscape. Results also indicated that diazotroph assemblages associated with different plant hosts growing in the same area of the marsh were structurally similar confirming the influence of edaphic parameters on these assemblages. Principal Component Analysis of DGGE gel banding patterns confirmed these results. This article reviews and analyzes data from North Inlet Estuary, addressing diazotroph assemblage structure and the influence of plant host and environmental conditions. New data demonstrate the heterogeneity of salt marsh rhizosphere microenvironments, and corroborate previous findings from different plant hosts growing at several locations within this estuary. These data support the hypothesis that the biogeography of microorganisms is non-random and is partially driven by

  18. Diazotrophic bacteria and nitrogen fertilization on the growth of micropropagated pineapple plantlets during acclimatization

    OpenAIRE

    2016-01-01

    ABSTRACT: This study examines the effect of inoculation with diazotrophic bacteria and nitrogen fertilization on the growth of micropropagated pineapple cv. 'Vitória' plantlets during the acclimatization period. The experiment was carried out in a greenhouse in Campos dos Goytacazes, in randomized blocks, using a 2x5x5 factorial scheme, with the factors being two types of inocula (absence or presence of a mixture of diazotrophic bacteria that contained Burkholderia sp. UENF 114111, Burkholder...

  19. Characterization of five putative aspartate aminotransferase genes in the N2-fixing heterocystous cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Xu, Xinyi; Gu, Liping; He, Ping; Zhou, Ruanbao

    2015-06-01

    Aspartate and glutamate are two key amino acids used in biosynthesis of many amino acids that play vital role in cellular metabolism. Aspartate aminotransferases (AspATs) are required for channelling nitrogen (N(2)) between Glu and Asp in all life forms. Biochemical and genetic characterization of AspATs have been lacking in N(2)-fixing cyanobacteria. In this report, five putative AspAT genes (alr1039, all2340, alr2765, all4327 and alr4853) were identified in the N(2)-fixing heterocystous cyanobacterium Anabaena sp. PCC 7120. Five recombinant C-terminal hexahistidine-tagged AspATs (AspAT-H(6)) were overexpressed in Escherichia coli and purified to homogeneity. Biochemical analysis demonstrated that these five putative AspATs have authentic AspAT activity in vitro using aspartate as an amino donor. However, the enzymic activities of the five AspATs differed in vitro. Alr4853-H(6) showed the highest AspAT activity, while the enzymic activity for the other four AspATs ranged from 6.5 to 53.7 % activity compared to Alr4853 (100 %). Genetic characterization of the five AspAT genes was also performed by inactivating each individual gene. All of the five AspAT knockout mutants exhibited reduced diazotrophic growth, and alr4853 was further identified to be a Fox gene (requiring fixed N(2) for growth in the presence of oxygen). Four out of five P(aspAT)-gfp transcriptional fusions were constitutively expressed in both diazotrophic and nitrate-dependent growth conditions. Quantitative reverse transcriptase PCR showed that alr4853 expression was increased by 2.3-fold after 24 h of N(2) deprivation. Taken together, these findings add to our understanding of the role of AspATs in N(2)-fixing within heterocystous cyanobacteria.

  20. Diazotroph diversity in the sea ice, melt ponds and surface waters of the Eurasian Basin of the Central Arctic Ocean

    OpenAIRE

    Fernández-Méndez, Mar; Turk-Kubo, Kendra A.; Rapp, Josephine Z.; Buttigieg, Pier Luigi; Krumpen, Thomas; Jonathan P Zehr; Boetius, Antje

    2016-01-01

    The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which ...

  1. The shifts of diazotrophic communities in spring and summer associated with coral Galaxea astreata, Pavona decussata and Porites lutea

    OpenAIRE

    Yanying Zhang; Qingsong Yang; Juan Ling; Joy Van Nostrand; Zhou Shi; Jizhong Zhou; Junde Dong

    2016-01-01

    The coral holobiont often resides in oligotrophic waters; both coral cells and their symbiotic dinoflagellates possess ammonium assimilation enzymes and potentially benefit from the nitrogen fixation of coral-associated diazotrophs. However, the seasonal dynamics of coral-associated diazotrophs are not well characterized. Here, the seasonal variations of diazotrophic communities associated with three corals, Galaxea astreata, Pavona decussata, and Porites lutea, were studied using nifH gene a...

  2. The shifts of diazotrophic communities in spring and summer associated with coral Galaxea astreata, Pavona decussata and Porites lutea

    OpenAIRE

    Yanying Zhang; Qingsong Yang; Juan Ling; Joy Van Nostrand; Zhou Shi; Jizhong Zhou; Junde Dong

    2016-01-01

    The coral holobiont often resides in oligotrophic waters; both coral cells and their symbiotic dinoflagellates possess ammonium assimilation enzymes and potentially benefit from the nitrogen fixation of coral-associated diazotrophs. However, the seasonal dynamics of coral-associated diazotrophs are not well characterized. Here, the seasonal variations of diazotrophic communities associated with three corals, Galaxea astreata, Pavona decussata and Porites lutea, were studied using nifH gene am...

  3. Investigating Microbial Activity in Diazotrophic Methane Seep Sediment via Transcript Analysis and Single-Cell FISH-NanoSIMS

    Science.gov (United States)

    Dekas, A. E.; Connon, S. A.; Chadwick, G.; Orphan, V. J.

    2012-12-01

    Methane seep microbial ecosystems are phylogenetically diverse and physiologically complex, and require culture-independent techniques to accurately investigate metabolic activity. In the present study we combine an RNA analysis of four key microbial genes with FISH-NanoSIMS analysis of single cells to determine the diversity of nitrogen fixing microorganisms (diazotrophs) present at a deep-sea methane-seeping site, as well as investigate the methane-dependency of a variety of community members. Recently, methane-dependent nitrogen fixation was observed in Mound 12 Costa Rica sediments, and was spatially correlated with the abundance of aggregates of anaerobic methanotrophic archaea (ANME) and sulfate reducing bacterial symbionts (SRB). Combined with the detection of 15N uptake from 15N2 in these aggregates, this suggested that the ANME-SRB aggregates are the primary diazotrophs in seep sediment. However, the diversity of dinitrogenase reductase (nifH) sequences recovered from several deep-sea locales, including Mound 12, suggests a greater diversity of diazotrophs in marine sediment. To investigate the activity of these potential diazotrophs in Mound 12 sediment, we investigated a suite of RNA transcripts in 15N2 incubations in both the presence and absence of methane: nifH, bacterial 16S rRNA, methyl coenzyme M reductase A (mcrA), and adenosine-5'-phosposulfate reductase alpha subunit (aprA). No nifH transcripts were recovered in incubations without methane, consistent with previous measurements lacking 15N2 uptake in the same sediments. The activity of the bacterial community in general, assessed by variable transcription, was also greatly affected by the presence or absence of methane. Single-cell fluorescence in situ hybridization coupled to nanoscale secondary ion mass spectrometry (FISH-NanoSIMS) was employed to confirm diazotrophic activity (15N2 uptake) and protein synthesis (15NH4+ uptake) of particular species implicated as ecologically important by the

  4. Diazotroph community succession during the VAHINE mesocosms experiment (New Caledonia Lagoon

    Directory of Open Access Journals (Sweden)

    K. A. Turk-Kubo

    2015-06-01

    Full Text Available The VAHINE mesocosm experiment, conducted in the low-nutrient low-chlorophyll waters of the Noumea Lagoon (coastal New Caledonia was designed to trace the incorporation of nitrogen (N fixed by diazotrophs into the food web, using large volume (50 m3 mesocosms. This experiment provided a unique opportunity to study the succession of different N2-fixing microorganisms (diazotrophs and calculate in situ net growth and loss rates in response to fertilization with dissolved inorganic phosphate (DIP over a 23 day period, using quantitative polymerase chain reaction (qPCR assays. Inside the mesocosms, the diazotroph community assemblage was dominated by the heterocyst-forming Richelia associated with Rhizosolenia (Het-1 in the first half of the experiment, and unicellularcyanobacterial Group C (UCYN-C became the dominant diazotroph in the second half of the experiment. Decreasing DIP concentrations following the fertilization event and increasing temperatures were significantly correlated with increasing abundances of UCYN-C. Maximum net growth rates for UCYN-C were calculated to be between 1.23 ± 0.07 and 2.16 ± 0.07 d−1 which are among the highest growth rates reported for diazotrophs. Outside the mesocosms in the Noumea Lagoon, UCYN-C abundances remained low, despite increasing temperatures, suggesting that the microbial community response to the DIP fertilization created conditions favorable for UCYN-C growth inside the mesocosms. Maximum net growth and loss rates for nine diazotroph phylotypes throughout the 23 day experiment were variable between mesocosms, and repeated fluctuations between periods of net growth and loss were commonly observed. The field population of diazotrophs in the Noumea Lagoon, was dominated by Het-1 over the course of the study period. However, eight additional diazotroph phylotypes were present in the lagoon at lower abundances, indicating a diverse field population of diazotrophs. Two ecotypes of the Braarudosphaera

  5. Isolation of endophytic diazotroph Pantoea agglomerans and nondiazotroph Enterobacter asburiae from sweetpotato stem in Japan.

    Science.gov (United States)

    Asis, C A; Adachi, K

    2004-01-01

    To isolate and identify diazotrophic endophytes in the stem of Japanese sweetpotato cv. Koganesengan. Surface-sterilized and thinly sliced (1-2 mm) sweetpotato stem samples were incubated in test tubes with semi-solid modified Rennie (MR) medium. The test tubes were assayed for acetylene reduction activity (ARA) 5 days after incubation at 30 degrees C. Twelve isolates were obtained from MR plates inoculated with a loop of semi-solid MR medium from ARA+ tubes. However, ARA test showed that only nine isolates were diazotrophic and three were nondiazotrophic strains. Using the API 20E diagnostic kit, four diazotrophic isolates were identified as strains of Pantoea spp. and five isolates as Klebsiella spp. The nondiazotrophic bacteria were strains of Enterobacter spp. A diazotrophic isolate Pantoea sp. MY1 and nondiazotrophic isolate Enterobacter sp. MY2 were identified to the species level by full sequence analysis of 16S rRNA gene. The results showed that MY1 had 99.2% similarity to Pantoea agglomerans ATCC 27155 and MY2 had 99.5% similarity to Enterobacter asburiae ATCC 35953. The stem of sweetpotato cv. Koganesengan was colonized by diazotrophic endophyte P. agglomerans and nondiazotrophic endophyte E. asburiae. This study is an essential step toward understanding the ecology and interaction between endophytic bacteria and sweetpotato.

  6. Diazotrophic diversity in the rhizosphere of two exotic weed plants, Prosopis juliflora and Parthenium hysterophorus.

    Science.gov (United States)

    Cibichakravarthy, B; Preetha, R; Sundaram, S P; Kumar, K; Balachandar, D

    2012-02-01

    This study is aimed at assessing culturable diazotrophic bacterial diversity in the rhizosphere of Prosopis juliflora and Parthenium hysterophorus, which grow profusely in nutritionally-poor soils and environmentally-stress conditions so as to identify some novel strains for bioinoculant technology. Diazotrophic isolates from Prosopis and Parthenium rhizosphere were characterized for nitrogenase activity by Acetylene Reduction Assay (ARA) and 16S rRNA gene sequencing. Further, the culture-independent quantitative PCR (qPCR) was performed to compare the abundance of diazotrophs in rhizosphere with bulk soils. The proportion of diazotrophs in total heterotrophs was higher in rhizosphere than bulk soils and 32 putative diazotrophs from rhizosphere of two plants were identified by nifH gene amplification. The ARA activity of the isolates ranged from 40 to 95 nmol ethylene h(-1) mg protein(-1). The 16S rRNA gene analysis identified the isolates to be members of alpha, beta and gamma Proteobacteria and firmicutes. The qPCR assay also confirmed that abundance of nif gene in rhizosphere of these two plants was 10-fold higher than bulk soil.

  7. Near-UV cyanobacteriochrome signaling system elicits negative phototaxis in the cyanobacterium Synechocystis sp. PCC 6803

    OpenAIRE

    Song, Ji-Young; Cho, Hye Sun; Cho, Jung-Il; Jeon, Jong-Seong; Lagarias, J. Clark; Park, Youn-Il

    2011-01-01

    Positive phototaxis systems have been well studied in bacteria; however, the photoreceptor(s) and their downstream signaling components that are responsible for negative phototaxis are poorly understood. Negative phototaxis sensory systems are important for cyanobacteria, oxygenic photosynthetic organisms that must contend with reactive oxygen species generated by an abundance of pigment photosensitizers. The unicellular cyanobacterium Synechocystis sp. PCC6803 exhibits type IV pilus-dependen...

  8. Sheep manure vermicompost supplemented with a native diazotrophic bacteria and mycorrhizas for maize cultivation.

    Science.gov (United States)

    Gutiérrez-Miceli, F A; Moguel-Zamudio, B; Abud-Archila, M; Gutiérrez-Oliva, V F; Dendooven, L

    2008-10-01

    An orthogonal experimental design L9 (3(4)) with 10 repetitions was used to investigate the effect of Glomus claroideum (0, 1 or 2g(-1) plant), G. fasciculatum (0, 1 or 2g plant(-1)), native diazotrophic bacteria (0, 10(3) and 10(5) UFC ml(-1)) and sheep manure vermicompost (0%, 5% and 10% v/v) on maize plant growth, N and P in leaves and mycorrhization percent. Vermicompost explained most of the variation found for leaf number, wet weight, stem height, and diameter. Both mycorrhizas increased the plant wet weight but G. fasciculatum the most. Mycorrhization increased the P content, but not the N content. Mycorrhizal colonization increased when diazotrophic bacteria and vermicompost were added. It was found that weight of maize plants cultivated in peat moss amended with vermicompost increased when supplemented with G. fasciculatum and diazotrophic bacteria.

  9. A Comprehensively Curated Genome-Scale Two-Cell Model for the Heterocystous Cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Malatinszky, David; Steuer, Ralf; Jones, Patrik R

    2017-01-01

    Anabaena sp. PCC 7120 is a nitrogen-fixing filamentous cyanobacterium. Under nitrogen-limiting conditions, a fraction of the vegetative cells in each filament terminally differentiate to nongrowing heterocysts. Heterocysts are metabolically and structurally specialized to enable O2-sensitive nitrogen fixation. The functionality of the filament, as an association of vegetative cells and heterocysts, is postulated to depend on metabolic exchange of electrons, carbon, and fixed nitrogen. In this study, we compile and evaluate a comprehensive curated stoichiometric model of this two-cell system, with the objective function based on the growth of the filament under diazotrophic conditions. The predicted growth rate under nitrogen-replete and -deplete conditions, as well as the effect of external carbon and nitrogen sources, was thereafter verified. Furthermore, the model was utilized to comprehensively evaluate the optimality of putative metabolic exchange reactions between heterocysts and vegetative cells. The model suggested that optimal growth requires at least four exchange metabolites. Several combinations of exchange metabolites resulted in predicted growth rates that are higher than growth rates achieved by only considering exchange of metabolites previously suggested in the literature. The curated model of the metabolic network of Anabaena sp. PCC 7120 enhances our ability to understand the metabolic organization of multicellular cyanobacteria and provides a platform for further study and engineering of their metabolism.

  10. Assimilation of diazotrophic nitrogen into pelagic food webs.

    Directory of Open Access Journals (Sweden)

    Ryan J Woodland

    Full Text Available The fate of diazotrophic nitrogen (N(D fixed by planktonic cyanobacteria in pelagic food webs remains unresolved, particularly for toxic cyanophytes that are selectively avoided by most herbivorous zooplankton. Current theory suggests that N(D fixed during cyanobacterial blooms can enter planktonic food webs contemporaneously with peak bloom biomass via direct grazing of zooplankton on cyanobacteria or via the uptake of bioavailable N(D (exuded from viable cyanobacterial cells by palatable phytoplankton or microbial consortia. Alternatively, N(D can enter planktonic food webs post-bloom following the remineralization of bloom detritus. Although the relative contribution of these processes to planktonic nutrient cycles is unknown, we hypothesized that assimilation of bioavailable N(D (e.g., nitrate, ammonium by palatable phytoplankton and subsequent grazing by zooplankton (either during or after the cyanobacterial bloom would be the primary pathway by which N(D was incorporated into the planktonic food web. Instead, in situ stable isotope measurements and grazing experiments clearly documented that the assimilation of N(D by zooplankton outpaced assimilation by palatable phytoplankton during a bloom of toxic Nodularia spumigena Mertens. We identified two distinct temporal phases in the trophic transfer of N(D from N. spumigena to the plankton community. The first phase was a highly dynamic transfer of N(D to zooplankton with rates that covaried with bloom biomass while bypassing other phytoplankton taxa; a trophic transfer that we infer was routed through bloom-associated bacteria. The second phase was a slowly accelerating assimilation of the dissolved-N(D pool by phytoplankton that was decoupled from contemporaneous variability in N. spumigena concentrations. These findings provide empirical evidence that N(D can be assimilated and transferred rapidly throughout natural plankton communities and yield insights into the specific processes

  11. Occurrence of diazotrophic bacteria in Araucaria angustifolia Ocorrência de bactérias diazotróficas em Araucaria angustifolia

    Directory of Open Access Journals (Sweden)

    Rafaela de Fátima Neroni

    2007-06-01

    Full Text Available Araucaria angustifolia is an environmentally threatened tree and the whole biota of the Araucaria Forest should be investigated with the aim of its preservation. Diazotrophic bacteria are extremely important for the maintenance of ecosystems, but they have never been studied in Araucaria Forests. In this study, diazotrophic bacteria were isolated from Araucaria roots and soil, when grown in semi-specific, semi-solid media. The diazotrophic character of some recovered isolates could be confirmed using the acetylene reduction assay. According to their 16S rRNA sequences, most of these isolates belong to the genus Burkholderia.Araucaria angustifolia é uma espécie arbórea ameaçada de extinção e toda a comunidade viva das Florestas de Araucária deve ser estudada com a finalidade de sua preservação. Bactérias diazotróficas apresentam grande importância para a manutenção de ecossistemas, mas sua ocorrência nunca foi pesquisada em araucária. Neste estudo foi demonstrada a associação de bactérias fixadoras de nitrogênio com A. angustifolia. Amostras de solo e raízes de araucária apresentaram a ocorrência de bactérias diazotróficas, quando inoculadas em meios semi-sólidos semi-específícos. O caráter diazotrófico de alguns isolados recuperados foi confirmado através da análise de redução do acetileno. De acordo com a análise das seqüências do 16S rRNA, estes isolados são na sua maioria pertencentes ao gênero Burkholderia.

  12. Seasonal variations in the diversity and abundance of diazotrophic communities across soils

    NARCIS (Netherlands)

    Pereira e Silva, Michele C.; Semenov, Alexander V.; van Elsas, Jan Dirk; Salles, Joana Falcao

    2011-01-01

    The nitrogen (N)-fixing community is a key functional community in soil, as it replenishes the pool of biologically available N that is lost to the atmosphere via anaerobic ammonium oxidation and denitrification. We characterized the structure and dynamic changes in diazotrophic communities, based o

  13. Performance of pineapple slips inoculated with diazotrophic phosphate-solubilizing bacteria and rock phosphate

    Directory of Open Access Journals (Sweden)

    Lílian Estrela Borges Baldotto

    2014-06-01

    Full Text Available Besides fixing N2, some diazotrophic bacteria or diazotrophs, also synthesize organic acids and are able to solubilize rock phosphates, increasing the availability of P for plants. The application of these bacteria to pineapple leaf axils in combination with rock phosphate could increase N and P availability for the crop, due to the bacterial activity of biological nitrogen fixation and phosphate solubilization. The objectives of this study were: (i to select and characterize diazotrophs able to solubilize phosphates in vitro and (ii evaluate the initial performance of the pineapple cultivars Imperial and Pérola in response to inoculation with selected bacteria in combination with rock phosphate. The experiments were conducted at Universidade Estadual do Norte Fluminense Darcy Ribeiro, in 2009. In the treatments with bacteria the leaf contents of N, P and K were higher than those of the controls, followed by an increase in plant growth. These results indicate that the combined application of diazotrophic phosphate-solubilizing bacteria Burkholderia together with Araxá rock phosphate can be used to improve the initial performance of pineapple slips.

  14. Diazotroph community structure and abundance in wheat-fallow and wheat-pea crop rotations

    Science.gov (United States)

    Biological input of nitrogen (N) from the atmosphere either through free-living diazotrophs or legume-associated rhizobia can help alleviate fertilizer use in agricultural systems. In this study, we investigated the effect of N fertilizer and winter pea (Pisum sativum L.) crop on the diversity and a...

  15. Phylogenetic changes in soil microbial and diazotrophic diversity with application of butachlor.

    Science.gov (United States)

    Yen, Jui-Hung; Wang, Yei-Shung; Hsu, Wey-Shin; Chen, Wen-Ching

    2013-01-01

    We investigated changes in population and taxonomic distribution of cultivable bacteria and diazotrophs with butachlor application in rice paddy soils. Population changes were measured by the traditional plate-count method, and taxonomic distribution was studied by 16S rDNA sequencing, then maximum parsimony phylogenic analysis with bootstrapping (1,000 replications). The bacterial population was higher after 39 than 7 days of rice cultivation, which indicated the augmentation of soil microbes by rice root exudates. The application of butachlor increased the diazotrophic population in both upper (0-3 cm) and lower (3-15 cm) layers of soils. Especially at day 39, the population of diazotrophs was 1.8 and 1.6 times that of the control in upper and lower layer soils, respectively. We found several bacterial strains only with butachlor application; examples are strains closest to Bacillus arsenicus, B. marisflavi, B. luciferensis, B. pumilus, and Pseudomonas alvei. Among diazotrophs, three strains closely related to Streptomyces sp. or Rhrizobium sp. were found only with butachlor application. The population of cultivable bacteria and the species composition were both changed with butachlor application, which explains in part the contribution of butachlor to augmenting soil nitrogen-fixing ability.

  16. Diazotrophic microbial community of coastal microbial mats of the southern North Sea.

    NARCIS (Netherlands)

    Bauersachs, T.; Compaoré, J.; Severin, I.; Hopmans, E.C.; Schouten, S.; Stal, L.J.; Sinninghe Damsté, J.S.

    2011-01-01

    The diazotrophic community in microbial mats growing along the shore of the North Sea barrier island Schiermonnikoog (The Netherlands) was studied using microscopy, lipid biomarkers, stable carbon (δ13CTOC) and nitrogen (δ15N) isotopes as well as by constructing and analyzing 16S rRNA gene

  17. Diazotrophic microbial community of coastal microbial mats of the southern North Sea

    NARCIS (Netherlands)

    Bauersachs, T.; Compaoré, J.; Severin, I.; Hopmans, E.C.; Schouten, S.; Stal, L.J.; Sinninghe Damsté, J.S.

    2011-01-01

    The diazotrophic community in microbial mats growing along the shore of the North Sea barrier island Schiermonnikoog (The Netherlands) was studied using microscopy, lipid biomarkers, stable carbon (delta(13)C(TOC)) and nitrogen (delta(15)N) isotopes as well as by constructing and analyzing 16S rRNA

  18. Diazotrophic microbial community of coastal microbial mats of the southern North Sea

    NARCIS (Netherlands)

    Bauersachs, T.; Compaore, J.; Severin, I.; Hopmans, E.C.; Schouten, S.; Stal, L.J.; Sinninghe Damsté, J.S.

    2011-01-01

    The diazotrophic community in microbial mats growing along the shore of the North Sea barrier island Schiermonnikoog (The Netherlands) was studied using microscopy, lipid biomarkers, stable carbon (δ13CTOC) and nitrogen (δ15N) isotopes as well as by constructing and analyzing 16S rRNA gene

  19. The Assimilation of Diazotroph-Derived Nitrogen by Scleractinian Corals Depends on Their Metabolic Status.

    Science.gov (United States)

    Bednarz, Vanessa N; Grover, Renaud; Maguer, Jean-François; Fine, Maoz; Ferrier-Pagès, Christine

    2017-01-10

    Tropical corals are associated with a diverse community of dinitrogen (N2)-fixing prokaryotes (diazotrophs) providing the coral an additional source of bioavailable nitrogen (N) in oligotrophic waters. The overall activity of these diazotrophs changes depending on the current environmental conditions, but to what extent it affects the assimilation of diazotroph-derived N (DDN) by corals is still unknown. Here, in a series of (15)N2 tracer experiments, we directly quantified DDN assimilation by scleractinian corals from the Red Sea exposed to different environmental conditions. We show that DDN assimilation strongly varied with the corals' metabolic status or with phosphate availability in the water. The very autotrophic shallow-water (~5 m) corals showed low or no DDN assimilation, which significantly increased under elevated phosphate availability (3 µM). Corals that depended more on heterotrophy (i.e., bleached and deep-water [~45 m] corals) assimilated significantly more DDN, which contributed up to 15% of the corals' N demand (compared to 1% in shallow corals). Furthermore, we demonstrate that a substantial part of the DDN assimilated by deep corals was likely obtained from heterotrophic feeding on fixed N compounds and/or diazotrophic cells in the mucus. Conversely, in shallow corals, the net release of mucus, rich in organic carbon compounds, likely enhanced diazotroph abundance and activity and thereby the release of fixed N to the pelagic and benthic reef community. Overall, our results suggest that DDN assimilation by corals varies according to the environmental conditions and is likely linked to the capacity of the coral to acquire nutrients from seawater.

  20. The Assimilation of Diazotroph-Derived Nitrogen by Scleractinian Corals Depends on Their Metabolic Status

    Science.gov (United States)

    Grover, Renaud; Maguer, Jean-François; Fine, Maoz; Ferrier-Pagès, Christine

    2017-01-01

    ABSTRACT Tropical corals are associated with a diverse community of dinitrogen (N2)-fixing prokaryotes (diazotrophs) providing the coral an additional source of bioavailable nitrogen (N) in oligotrophic waters. The overall activity of these diazotrophs changes depending on the current environmental conditions, but to what extent it affects the assimilation of diazotroph-derived N (DDN) by corals is still unknown. Here, in a series of 15N2 tracer experiments, we directly quantified DDN assimilation by scleractinian corals from the Red Sea exposed to different environmental conditions. We show that DDN assimilation strongly varied with the corals’ metabolic status or with phosphate availability in the water. The very autotrophic shallow-water (~5 m) corals showed low or no DDN assimilation, which significantly increased under elevated phosphate availability (3 µM). Corals that depended more on heterotrophy (i.e., bleached and deep-water [~45 m] corals) assimilated significantly more DDN, which contributed up to 15% of the corals’ N demand (compared to 1% in shallow corals). Furthermore, we demonstrate that a substantial part of the DDN assimilated by deep corals was likely obtained from heterotrophic feeding on fixed N compounds and/or diazotrophic cells in the mucus. Conversely, in shallow corals, the net release of mucus, rich in organic carbon compounds, likely enhanced diazotroph abundance and activity and thereby the release of fixed N to the pelagic and benthic reef community. Overall, our results suggest that DDN assimilation by corals varies according to the environmental conditions and is likely linked to the capacity of the coral to acquire nutrients from seawater. PMID:28074021

  1. Alterations in seedling vigour and antioxidant enzyme activities in Catharanthus roseus under seed priming with native diazotrophs

    Institute of Scientific and Technical Information of China (English)

    KARTHIKEYAN B.; JALEEL C.A.; GOPI R.; DEIVEEKASUNDARAM M.

    2007-01-01

    An experiment was conducted on Catharanthus roseus to study the effect of seed treatments with native diazotrophs on its seedling growth and antioxidant enzyme activities. The treatments had significant influence on various seedling parameters.There is no significant influence on dry matter production with the diazotrophs, Azospirillum and Azotobacter. However, the vital seedling parameters such as germination percentage and vigour index were improved. Azotobacter treatment influenced maximum of 50% germination, whereas Azospirillum and Azotobacter were on par with C. roseus with respect to their vigour index. There was significant difference in the population of total diazotrophs. Azospirillum and Azotobacter between rhizosphere and non-rhizosphere soils of C. roseus had the same trend and were observed at various locations of the study. The activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT) were increased to a significant extent due to the treatment with diazotrophs.

  2. In situ transcriptomic analysis of the globally important keystone N2-fixing taxon Crocosphaera watsonii.

    Science.gov (United States)

    Hewson, Ian; Poretsky, Rachel S; Beinart, Roxanne A; White, Angelicque E; Shi, Tuo; Bench, Shellie R; Moisander, Pia H; Paerl, Ryan W; Tripp, H James; Montoya, Joseph P; Moran, Mary Ann; Zehr, Jonathan P

    2009-05-01

    The diazotrophic cyanobacterium Crocosphaera watsonii supplies fixed nitrogen (N) to N-depleted surface waters of the tropical oceans, but the factors that determine its distribution and contribution to global N(2) fixation are not well constrained for natural populations. Despite the heterogeneity of the marine environment, the genome of C. watsonii is highly conserved in nucleotide sequence in contrast to sympatric planktonic cyanobacteria. We applied a whole assemblage shotgun transcript sequencing approach to samples collected from a bloom of C. watsonii observed in the South Pacific to understand the genomic mechanisms that may lead to high population densities. We obtained 999 C. watsonii transcript reads from two metatranscriptomes prepared from mixed assemblage RNA collected in the day and at night. The C. watsonii population had unexpectedly high transcription of hypothetical protein genes (31% of protein-encoding genes) and transposases (12%). Furthermore, genes were expressed that are necessary for living in the oligotrophic ocean, including the nitrogenase cluster and the iron-stress-induced protein A (isiA) that functions to protect photosystem I from high-light-induced damage. C. watsonii transcripts retrieved from metatranscriptomes at other locations in the southwest Pacific Ocean, station ALOHA and the equatorial Atlantic Ocean were similar in composition to those recovered in the enriched population. Quantitative PCR and quantitative reverse transcriptase PCR were used to confirm the high expression of these genes within the bloom, but transcription patterns varied at shallower and deeper horizons. These data represent the first transcript study of a rare individual microorganism in situ and provide insight into the mechanisms of genome diversification and the ecophysiology of natural populations of keystone organisms that are important in global nitrogen cycling.

  3. Insights into the physiology and ecology of the brackish-water-adapted Cyanobacterium Nodularia spumigena CCY9414 based on a genome-transcriptome analysis.

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    Björn Voss

    Full Text Available Nodularia spumigena is a filamentous diazotrophic cyanobacterium that dominates the annual late summer cyanobacterial blooms in the Baltic Sea. But N. spumigena also is common in brackish water bodies worldwide, suggesting special adaptation allowing it to thrive at moderate salinities. A draft genome analysis of N. spumigena sp. CCY9414 yielded a single scaffold of 5,462,271 nucleotides in length on which genes for 5,294 proteins were annotated. A subsequent strand-specific transcriptome analysis identified more than 6,000 putative transcriptional start sites (TSS. Orphan TSSs located in intergenic regions led us to predict 764 non-coding RNAs, among them 70 copies of a possible retrotransposon and several potential RNA regulators, some of which are also present in other N2-fixing cyanobacteria. Approximately 4% of the total coding capacity is devoted to the production of secondary metabolites, among them the potent hepatotoxin nodularin, the linear spumigin and the cyclic nodulapeptin. The transcriptional complexity associated with genes involved in nitrogen fixation and heterocyst differentiation is considerably smaller compared to other Nostocales. In contrast, sophisticated systems exist for the uptake and assimilation of iron and phosphorus compounds, for the synthesis of compatible solutes, and for the formation of gas vesicles, required for the active control of buoyancy. Hence, the annotation and interpretation of this sequence provides a vast array of clues into the genomic underpinnings of the physiology of this cyanobacterium and indicates in particular a competitive edge of N. spumigena in nutrient-limited brackish water ecosystems.

  4. Temporal changes in the diazotrophic bacterial communities associated with Caribbean sponges Ircinia stroblina and Mycale laxissima

    OpenAIRE

    Fan eZhang; Jan eVicente; Russell T. Hill

    2014-01-01

    Sponges that harbor microalgal or cyanobacterial symbionts may benefit from photosynthetically derived carbohydrates, which are rich in carbon but devoid of nitrogen, and may therefore encounter nitrogen limitation. Diazotrophic communities associated with two Caribbean sponges, Ircinia strobilina and Mycale laxissima were studied in a time series during which three individuals of each sponge were collected in four time points (5:00 AM, 12:00 noon, 5:00 PM, 10:00 PM). nifH genes were succes...

  5. "Cold" Fixation: Reconciliation of Nitrogen Fixation Rates and Diazotroph Assemblages in the Arctic Ocean

    Science.gov (United States)

    Fong, A. A.; Waite, A.; Rost, B.; Richter, K. U.

    2016-02-01

    Measurements of biological nitrogen fixation are typically conducted in oligotrophic subtropical and tropical marine environments where concentrations of fixed inorganic nitrogen are low. To date, only a handful of nitrogen fixation studies have been conducted in high latitude marine environments, but further investigation is needed to resolve the distribution of cold ocean diazotrophic assemblages. Nitrogen fixation rates and nifH gene distributions were measured at seven stations from 5°E to 20°E, north of 81°N in the Arctic Ocean at the onset of summer 2015. Discrete water samples in ice-covered regions were collected from the sea surface to 200 m for 15N2-tracer additions and targeted nifH gene and transcript analyses. Previous work suggests that heterotrophic bacteria dominate diazotrophic communities in the Arctic Ocean. Therefore, additional nifH gene surveys of sinking particles were conducted to test for enrichment on organic matter-rich microenvironments. Together, these measurements aim to reconcile diazotrophic activity with microbial community composition, further elucidating how nitrogen fixers could impact current concepts in polar carbon and nutrient cycling.

  6. Diazotrophic bacteria and nitrogen fertilization on the growth of micropropagated pineapple plantlets during acclimatization

    Directory of Open Access Journals (Sweden)

    Aurilena de Aviz Silva

    Full Text Available ABSTRACT: This study examines the effect of inoculation with diazotrophic bacteria and nitrogen fertilization on the growth of micropropagated pineapple cv. 'Vitória' plantlets during the acclimatization period. The experiment was carried out in a greenhouse in Campos dos Goytacazes, in randomized blocks, using a 2x5x5 factorial scheme, with the factors being two types of inocula (absence or presence of a mixture of diazotrophic bacteria that contained Burkholderia sp. UENF 114111, Burkholderia silvatlantica UENF 11711, and Herbaspirillum seropedicae HRC 54, five levels of urea (0, 2, 5, 7, and 10g L-1, and five evaluation periods (30, 60, 90, 120, and 150 days following the planting of plantlets in trays, and with four replications of each treatment. An increase in the dried weight of shoots and roots of micropropagated pineapple cv. 'Vitória' plants depended on inoculation with diazotrophic bacteria, and plantlets acclimatization could be reduced by up to 57 days, depending on the concentration of urea fertilizer.

  7. Molecular characterization of Alr1105 a novel arsenate reductase of the diazotrophic cyanobacterium Anabaena sp. PCC7120 and decoding its role in abiotic stress management in Escherichia coli.

    Science.gov (United States)

    Pandey, Sarita; Shrivastava, Alok K; Rai, Rashmi; Rai, Lal Chand

    2013-11-01

    This paper constitutes the first report on the Alr1105 of Anabaena sp. PCC7120 which functions as arsenate reductase and phosphatase and offers tolerance against oxidative and other abiotic stresses in the alr1105 transformed Escherichia coli. The bonafide of 40.8 kDa recombinant GST+Alr1105 fusion protein was confirmed by immunoblotting. The purified Alr1105 protein (mw 14.8 kDa) possessed strong arsenate reductase (Km 16.0 ± 1.2 mM and Vmax 5.6 ± 0.31 μmol min⁻¹ mg protein⁻¹) and phosphatase activity (Km 27.38 ± 3.1 mM and Vmax 0.077 ± 0.005 μmol min⁻¹ mg protein⁻¹) at an optimum temperature 37 °C and 6.5 pH. Native Alr1105 was found as a monomeric protein in contrast to its homologous Synechocystis ArsC protein. Expression of Alr1105 enhanced the arsenic tolerance in the arsenate reductase mutant E. coli WC3110 (∆arsC) and rendered better growth than the wild type W3110 up to 40 mM As (V). Notwithstanding above, the recombinant E. coli strain when exposed to CdCl₂, ZnSO₄, NiCl₂, CoCl₂, CuCl₂, heat, UV-B and carbofuron showed increase in growth over the wild type and mutant E. coli transformed with the empty vector. Furthermore, an enhanced growth of the recombinant E. coli in the presence of oxidative stress producing chemicals (MV, PMS and H₂O₂), suggested its protective role against these stresses. Appreciable expression of alr1105 gene as measured by qRT-PCR at different time points under selected stresses reconfirmed its role in stress tolerance. Thus the Alr1105 of Anabaena sp. PCC7120 functions as an arsenate reductase and possess novel properties different from the arsenate reductases known so far.

  8. Assessment of the effect of azo dye RP2B on the growth of a nitrogen fixing cyanobacterium--Anabaena sp.

    Science.gov (United States)

    Hu, T L; Wu, S C

    2001-03-01

    Certain nitrogen fixing cyanobacteria are diazotrophic, which profoundly impacts the aquatic ecosystem chemically and biologically. Although certain types are banned due to their carcinogenicity, azo dyes are commonly used in the dyeing or textile industry. This work investigates the effect of azo dye on the growth of cyanobacteria. Anabaena sp. isolated from the Da Jia Brook is an odor producing, nitrogen fixing cyanobacterium. The growth rates of Anabaena sp. in the media with or without nitrogen source were 3.56 x 10(-2) mg/ml day and 2.44 x 10(-2) mg/ml day, respectively. Anabaena sp. could not use azo dye RP2B as the nitrogen source. Experimental results indicated that the growth of Anabaena sp. was inhibited in the medium containing RP2B. The degree of inhibition increased from 50% to 81% with an increasing concentration of RP2B (0-50 mg/l). The IC-50 (inhibitory concentration) of RP2B on the growth of Anabaena sp. was 5 mg/l (as based on dry weight) or 7 mg/l (as measured by chlorophyll a).

  9. Exploring the size limit of protein diffusion through the periplasm in cyanobacterium Anabaena sp. PCC 7120 using the 13 kDa iLOV fluorescent protein.

    Science.gov (United States)

    Zhang, Li-Chen; Risoul, Véronique; Latifi, Amel; Christie, John M; Zhang, Cheng-Cai

    2013-09-01

    In the filamentous heterocyst-forming cyanobacterium Anabaena PCC 7120, vegetative cells and heterocysts are interdependent on each other and engaged in exchanges of metabolites for survival when grown under diazotrophic conditions. In this organism, the periplasm appears to be continuous along each filament, with a shared outer membrane; however, barriers exist preventing free diffusion of the fluorescent protein GFP (27 kDa) targeted into the periplasmic space. Here we expressed a smaller fluorescent protein iLOV (≈ 13 kDa) fused to the All3333 (a putative homologue of NrtA) signal sequence corresponding to those recognized by the TAT protein translocation system, which exports iLOV to the periplasm of either heterocysts or vegetative cells. Fluorescence microscopy and immunoblot analysis indicated that the iLOV protein is translocated into the periplasm of the producing cell and properly processed, but does not diffuse to neighboring cells via the periplasm. Thus, periplasmic barriers appear to block diffusion of molecules with a size of 13 kDa, the minimum size tested thus far. Assuming that the physical barrier is the peptidoglycan sacculus, its pores might allow diffusion of molecules within the size range between the PatS pentapeptide and iLOV, thus between 0.53 kDa and 13 kDa.

  10. Alr5068, a Low-Molecular-Weight protein tyrosine phosphatase, is involved in formation of the heterocysts polysaccharide layer in the cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Tan, Hui; Wan, Shuang; Liu, Pi-Qiong; Wang, Li; Zhang, Cheng-Cai; Chen, Wen-Li

    2013-10-01

    The filamentous cyanobacterium Anabaena sp. PCC 7120 forms nitrogen-fixing heterocysts after deprivation of combined nitrogen. Under such conditions, vegetative cells provide heterocysts with photosynthate and receive fixed nitrogen from the latter. Heterocyst envelope contains a glycolipid layer and a polysaccharide layer to restrict the diffusion of oxygen into heterocysts. Low-Molecular-Weight protein tyrosine phosphatases (LMW-PTPs) are involved in the biosynthesis of exopolysaccharides in bacteria. Alr5068, a protein from Anabaena sp. PCC 7120, shows significant sequence similarity with LMW-PTPs. In this study we characterized the enzymatic properties of Alr5068 and showed that it can dephosphorylate several autophosphorylated tyrosine kinases (Alr2856, Alr3059 and All4432) of Anabaena sp. PCC 7120 in vitro. Several conserved residues among LMW-PTPs are shown to be essential for the phosphatase activity of Alr5068. Overexpression of alr5068 results in a strain unable to survive under diazotrophic conditions, with the formation of morphologically mature heterocysts detached from the filaments. Overexpression of an alr5068 allele that lost phosphatase activity led to the formation of heterocyst with an impaired polysaccharide layer. The alr5068 gene was upregulated after nitrogen step-down and its mutation affected the expression of hepA and hepC, two genes necessary for the formation of the heterocyst envelope polysaccharide (HEP) layer. Our results suggest that Alr5068 is associated with the production of HEP in Anabaena sp. PCC 7120.

  11. High-yield production of extracellular type-I cellulose by the cyanobacterium Synechococcus sp. PCC 7002.

    Science.gov (United States)

    Zhao, Chi; Li, Zhongkui; Li, Tao; Zhang, Yingjiao; Bryant, Donald A; Zhao, Jindong

    2015-01-01

    Cellulose synthase, encoded by the cesA gene, is responsible for the synthesis of cellulose in nature. We show that the cell wall of the cyanobacterium Synechococcus sp. PCC 7002 naturally contains cellulose. Cellulose occurs as a possibly laminated layer between the inner and outer membrane, as well as being an important component of the extracellular glycocalyx in this cyanobacterium. Overexpression of six genes, cmc-ccp-cesAB-cesC-cesD-bgl, from Gluconacetobacter xylinus in Synechococcus sp. PCC 7002 resulted in very high-yield production of extracellular type-I cellulose. High-level cellulose production only occurred when the native cesA gene was inactivated and when cells were grown at low salinity. This system provides a method for the production of lignin-free cellulose from sunlight and CO2 for biofuel production and other biotechnological applications.

  12. Comparative study of endophytic and endophytic diazotrophic bacterial communities across rice landraces grown in the highlands of northern Thailand.

    Science.gov (United States)

    Rangjaroen, Chakrapong; Rerkasem, Benjavan; Teaumroong, Neung; Sungthong, Rungroch; Lumyong, Saisamorn

    2014-01-01

    Communities of bacterial endophytes within the rice landraces cultivated in the highlands of northern Thailand were studied using fingerprinting data of 16S rRNA and nifH genes profiling by polymerase chain reaction-denaturing gradient gel electrophoresis. The bacterial communities' richness, diversity index, evenness, and stability were varied depending on the plant tissues, stages of growth, and rice cultivars. These indices for the endophytic diazotrophic bacteria within the landrace rice Bue Wah Bo were significantly the lowest. The endophytic bacteria revealed greater diversity by cluster analysis with seven clusters compared to the endophytic diazotrophic bacteria (three clusters). Principal component analysis suggested that the endophytic bacteria showed that the community structures across the rice landraces had a higher stability than those of the endophytic diazotrophic bacteria. Uncultured bacteria were found dominantly in both bacterial communities, while higher generic varieties were observed in the endophytic diazotrophic bacterial community. These differences in bacterial communities might be influenced either by genetic variation in the rice landraces or the rice cultivation system, where the nitrogen input affects the endophytic diazotrophic bacterial community.

  13. Influence of nitrogen fertilization on diazotrophic communities in the rhizosphere of the Jerusalem artichoke (Helianthus tuberosus L.).

    Science.gov (United States)

    Meng, Xianfa; Wang, Lin; Long, Xiaohua; Liu, Zhaopu; Zhang, Zhenhua; Zed, Rengel

    2012-06-01

    Diazotrophs in the soil may be influenced by plant factors as well as nitrogen (N) fertilization. In this study, we investigated potential diazotrophic communities in the rhizosphere of the Jerusalem artichoke (Helianthus tuberosus L.) supplied with differing amounts of N. The community structure of N(2)-fixing bacteria was profiled using the length heterogeneity polymerase chain reaction (LH-PCR) and terminal restriction fragment length polymorphism (T-RFLP) based on a variation in the nifH gene. Higher numbers of diazotrophs were detected by T-RFLP compared to LH-PCR. The lowest number of N(2)-fixing bacteria was observed in the rhizosphere soil with high N fertilization. T-RFLP was a better method than LH-PCR for profiling microbial diversity of diazotrophs using multidimensional scaling (MDS) and analysis of similarity (ANOSIM) of fingerprints as well as diversity measures. The supply of N fertilizer appeared to negatively influence the abundance of diazotrophs in the rhizophere of the Jerusalem artichoke.

  14. Photosystem I from the unusual cyanobacterium Gloeobacter violaceus

    NARCIS (Netherlands)

    Mangels, D.; Kruip, J.; Berry, S.; Rögner, M.; Boekema, E.J.; Koenig, F.

    2002-01-01

    Photosystem I (PS I) from the primitive cyanobacterium Gloeobacter violaceus has been purified and characterised. Despite the fact that the isolated complexes have the same subunit composition as complexes from other cyanobacteria, the amplitude of flash-induced absorption difference spectra

  15. Photosystem I from the unusual cyanobacterium Gloeobacter violaceus

    NARCIS (Netherlands)

    Mangels, D.; Kruip, J.; Berry, S.; Rögner, M.; Boekema, E.J.; Koenig, F.

    2002-01-01

    Photosystem I (PS I) from the primitive cyanobacterium Gloeobacter violaceus has been purified and characterised. Despite the fact that the isolated complexes have the same subunit composition as complexes from other cyanobacteria, the amplitude of flash-induced absorption difference spectra indicat

  16. Complete Genome Sequence of the Cyanobacterium Anabaena sp. 33047

    Science.gov (United States)

    2016-01-01

    This study presents the complete nucleotide sequence of Anabaena sp. ATCC 33047 (Anabaena CA), a filamentous, nitrogen-fixing marine cyanobacterium, which under salt stress conditions accumulates sucrose internally. The elucidation of the genome will contribute to the understanding of cyanobacterial diversity. PMID:27516507

  17. Structure of plastocyanin from the cyanobacterium Anabaena variabilis

    DEFF Research Database (Denmark)

    Schmidt, Lars; Christensen, Hans Erik Mølager; Harris, Pernille

    2006-01-01

    Plastocyanin from the cyanobacterium Anabaena variabilis was heterologously produced in E. coli and purified. Plate-like crystals were obtained by crystallisation in 1.15 M trisodium citrate and 7.67 mM sodium borate buffer pH 8.5. The crystals belong to the orthorhombic space group P212121...

  18. Lactate dehydrogenase in the cyanobacterium Microcystis PCC7806

    NARCIS (Netherlands)

    Moezelaar, R.; Teixeira, de M.J.; Stal, L.J.

    1995-01-01

    The cyanobacterium Microcystis PCC7806 was found to possess an NAD-dependent lactate dehydrogenase (EC 1.1.1.27) which catalyzes the reduction of pyruvate to l-lactate. The enzyme required fructose 1,6-bisphosphate for activity and displayed positive cooperativity towards pyruvate. Lactate was not

  19. Binding characteristics of copper and cadmium by cyanobacterium Spirulina platensis

    Energy Technology Data Exchange (ETDEWEB)

    Fang Linchuan [State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070 (China); Zhou Chen; Cai Peng [Key Laboratory of Subtropical Agricultural Resources and Environment, Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China); Chen Wenli [State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070 (China); Rong Xingmin; Dai Ke; Liang Wei [Key Laboratory of Subtropical Agricultural Resources and Environment, Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China); Gu Jidong [Department of Ecology and Biodiversity, University of Hong Kong, Pokfulam Road, Hong Kong (Hong Kong); Huang Qiaoyun, E-mail: qyhuang@mail.hzau.edu.cn [State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070 (China); Key Laboratory of Subtropical Agricultural Resources and Environment, Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China)

    2011-06-15

    Highlights: {yields} The carboxyl groups play a vital role in the binding of Cu(II) and Cd(II) to S. platensis cells. {yields} Ion exchange and complexation are the dominating mechanism for Cu(II) and Cd(II) adsorption. {yields} XAFS analysis provided evidence for the inner-sphere complexation of Cu by carboxyl ligands and showed that Cu is complexed by two 5-membered chelate rings on S. platensis surface. - Abstract: Cyanobacteria are promising biosorbent for heavy metals in bioremediation. Although sequestration of metals by cyanobacteria is known, the actual mechanisms and ligands involved are not very well understood. The binding characteristics of Cu(II) and Cd(II) by the cyanobacterium Spirulina platensis were investigated using a combination of chemical modifications, batch adsorption experiments, Fourier transform infrared (FTIR) spectroscopy and X-ray absorption fine structure (XAFS) spectroscopy. A significant increase in Cu(II) and Cd(II) binding was observed in the range of pH 3.5-5.0. Dramatical decrease in adsorption of Cu(II) and Cd(II) was observed after methanol esterification of the nonliving cells demonstrating that carboxyl functional groups play an important role in the binding of metals by S. platensis. The desorption rate of Cu(II) and Cd(II) from S. platensis surface was 72.7-80.7% and 53.7-58.0% by EDTA and NH{sub 4}NO{sub 3}, respectively, indicating that ion exchange and complexation are the dominating mechanisms for Cu(II) and Cd(II) adsorption. XAFS analysis provided further evidence on the inner-sphere complexation of Cu by carboxyl ligands and showed that Cu is complexed by two 5-membered chelate rings on S. platensis surface.

  20. Antagonistic interactions between filamentous heterotrophs and the cyanobacterium Nostoc muscorum.

    Science.gov (United States)

    Svercel, Miroslav; Saladin, Bianca; van Moorsel, Sofia J; Wolf, Sarah; Bagheri, Homayoun C

    2011-09-13

    Little is known about interactions between filamentous heterotrophs and filamentous cyanobacteria. Here, interactions between the filamentous heterotrophic bacteria Fibrella aestuarina (strain BUZ 2) and Fibrisoma limi (BUZ 3) with an axenic strain of the autotrophic filamentous cyanobacterium Nostoc muscorum (SAG 25.82) were studied in mixed cultures under nutrient rich (carbon source present in medium) and poor (carbon source absent in medium) conditions. F. aestuarina BUZ 2 significantly reduced the cyanobacterial population whereas F. limi BUZ 3 did not. Physical contact between heterotrophs and autotroph was observed and the cyanobacterial cells showed some level of damage and lysis. Therefore, either contact lysis or entrapment with production of extracellular compounds in close vicinity of host cells could be considered as potential modes of action.The supernatants from pure heterotrophic cultures did not have an effect on Nostoc cultures. However, supernatant from mixed cultures of BUZ 2 and Nostoc had a negative effect on cyanobacterial growth, indicating that the lytic compounds were only produced in the presence of Nostoc.The growth and survival of tested heterotrophs was enhanced by the presence of Nostoc or its metabolites, suggesting that the heterotrophs could utilize the autotrophs and its products as a nutrient source. However, the autotroph could withstand and out-compete the heterotrophs under nutrient poor conditions. Our results suggest that the nutrients in cultivation media, which boost or reduce the number of heterotrophs, were the important factor influencing the outcome of the interplay between filamentous heterotrophs and autotrophs. For better understanding of these interactions, additional research is needed. In particular, it is necessary to elucidate the mode of action for lysis by heterotrophs, and the possible defense mechanisms of the autotrophs.

  1. Antagonistic interactions between filamentous heterotrophs and the cyanobacterium Nostoc muscorum

    Directory of Open Access Journals (Sweden)

    Wolf Sarah

    2011-09-01

    Full Text Available Abstract Background Little is known about interactions between filamentous heterotrophs and filamentous cyanobacteria. Here, interactions between the filamentous heterotrophic bacteria Fibrella aestuarina (strain BUZ 2 and Fibrisoma limi (BUZ 3 with an axenic strain of the autotrophic filamentous cyanobacterium Nostoc muscorum (SAG 25.82 were studied in mixed cultures under nutrient rich (carbon source present in medium and poor (carbon source absent in medium conditions. Findings F. aestuarina BUZ 2 significantly reduced the cyanobacterial population whereas F. limi BUZ 3 did not. Physical contact between heterotrophs and autotroph was observed and the cyanobacterial cells showed some level of damage and lysis. Therefore, either contact lysis or entrapment with production of extracellular compounds in close vicinity of host cells could be considered as potential modes of action. The supernatants from pure heterotrophic cultures did not have an effect on Nostoc cultures. However, supernatant from mixed cultures of BUZ 2 and Nostoc had a negative effect on cyanobacterial growth, indicating that the lytic compounds were only produced in the presence of Nostoc. The growth and survival of tested heterotrophs was enhanced by the presence of Nostoc or its metabolites, suggesting that the heterotrophs could utilize the autotrophs and its products as a nutrient source. However, the autotroph could withstand and out-compete the heterotrophs under nutrient poor conditions. Conclusions Our results suggest that the nutrients in cultivation media, which boost or reduce the number of heterotrophs, were the important factor influencing the outcome of the interplay between filamentous heterotrophs and autotrophs. For better understanding of these interactions, additional research is needed. In particular, it is necessary to elucidate the mode of action for lysis by heterotrophs, and the possible defense mechanisms of the autotrophs.

  2. Evidence for the endophytic colonization of Phaseolus vulgaris(common bean roots by the diazotroph Herbaspirillum seropedicae

    Directory of Open Access Journals (Sweden)

    M.A. Schmidt

    2011-03-01

    Full Text Available Herbaspirillum seropedicae is an endophytic diazotrophic bacterium, which associates with important agricultural plants. In the present study, we have investigated the attachment to and internal colonization of Phaseolus vulgaris roots by the H. seropedicae wild-type strain SMR1 and by a strain of H. seropedicae expressing a red fluorescent protein (DsRed to track the bacterium in the plant tissues. Two-day-old P. vulgaris roots were incubated at 30°C for 15 min with 6 x 10(8 CFU/mL H. seropedicae SMR1 or RAM4. Three days after inoculation, 4 x 10(4 cells of endophytic H. seropedicae SMR1 were recovered per gram of fresh root, and 9 days after inoculation the number of endophytes increased to 4 x 10(6 CFU/g. The identity of the recovered bacteria was confirmed by amplification and sequencing of the 16SrRNA gene. Furthermore, confocal microscopy of P. vulgaris roots inoculated with H. seropedicae RAM4 showed that the bacterial cells were attached to the root surface 15 min after inoculation; fluorescent bacteria were visible in the internal tissues after 24 h and were found in the central cylinder after 72 h, showing that H. seropedicae RAM4 is capable of colonizing the roots of the dicotyledon P. vulgaris. Determination of dry weight of common bean inoculated with H. seropedicae SMR1 suggested that this bacterium has a negative effect on the growth of P. vulgaris.

  3. Distribution of diazotrophic microorganisms and nifH gene expression in the Mekong River plume during intermonsoon

    DEFF Research Database (Denmark)

    Bombar, Deniz; Moisander, Pia H.; Dippner, Joachim W.

    2011-01-01

    N 2 fixation by marine pelagic prokaryotes plays a critical role in supplying new N to the ocean, and there is growing evidence that oceanic N 2 fixation is generally enhanced in tropical river plumes, where N 2 fixers (diazotrophs) benefit from riverine phosphorus and/or iron. Here we used nif......H gene quantitative polymerase chain reaction (QPCR) and reverse transcription (RT) QPCR to investigate the horizontal distribution and activity of 9 diazotroph phylotypes in the Mekong River plume, South China Sea (SCS), in April 2007 (intermonsoon, lowest annual discharge). The nifH gene diversity...... was investigated by cloning and sequencing. Hydrodynamic modeling of the surface water advection revealed that the same water masses were sampled during the entire study, and helped to elucidate the physical forcing on diazotroph abundances and distributions. According to our estimates of nifH abundances...

  4. Indirect Interspecies Regulation: Transcriptional and Physiological Responses of a Cyanobacterium to Heterotrophic Partnership

    Science.gov (United States)

    McClure, Ryan S.; Thiel, Vera; Sadler, Natalie C.; Kim, Young-Mo; Chrisler, William B.; Hill, Eric A.; Romine, Margaret F.; Jansson, Janet K.; Fredrickson, Jim K.; Beliaev, Alexander S.

    2017-01-01

    ABSTRACT The mechanisms by which microbes interact in communities remain poorly understood. Here, we interrogated specific interactions between photoautotrophic and heterotrophic members of a model consortium to infer mechanisms that mediate metabolic coupling and acclimation to partnership. This binary consortium was composed of a cyanobacterium, Thermosynechococcus elongatus BP-1, which supported growth of an obligate aerobic heterotroph, Meiothermus ruber strain A, by providing organic carbon, O2, and reduced nitrogen. Species-resolved transcriptomic analyses were used in combination with growth and photosynthesis kinetics to infer interactions and the environmental context under which they occur. We found that the efficiency of biomass production and resistance to stress induced by high levels of dissolved O2 increased, beyond axenic performance, as a result of heterotrophic partnership. Coordinated transcriptional responses transcending both species were observed and used to infer specific interactions resulting from the synthesis and exchange of resources. The cyanobacterium responded to heterotrophic partnership by altering expression of core genes involved with photosynthesis, carbon uptake/fixation, vitamin synthesis, and scavenging of reactive oxygen species (ROS). IMPORTANCE This study elucidates how a cyanobacterial primary producer acclimates to heterotrophic partnership by modulating the expression levels of key metabolic genes. Heterotrophic bacteria can indirectly regulate the physiology of the photoautotrophic primary producers, resulting in physiological changes identified here, such as increased intracellular ROS. Some of the interactions inferred from this model system represent putative principles of metabolic coupling in phototrophic-heterotrophic partnerships. PMID:28289730

  5. Encystment of Azotobacter nigricans grown diazotrophically on kerosene as sole carbon source.

    Science.gov (United States)

    García-Esquivel, Gabriela; Calva-Calva, Graciano; Ferrera-Cerrato, Ronald; Fernández-Linares, Luis Carlos; Vázquez, Refugio Rodríguez; Esparza-García, Fernando José

    2009-03-01

    Encystment of Azotobacter nigricans was induced by its diazotrophic cultivation on kerosene. Its growth and nitrogenase activity were affected by kerosene in comparison to cultures grown on sucrose. Electron microscopy of vegetative cells showed that when nitrogenase activity was higher and the poly-beta-hydroxybutyrate granules were not present to a significant extent, peripheral bodies were abundant. After 8 days of culture on kerosene, the presence of cysts with intracellular bunches of poly-beta-hydroxybutyrate granules was observed. Germination of cysts bears germinating multicelled yet unbroken capsule cysts with up to three cells inside. This is the first report of encystment induction of Azotobacter species grown on kerosene.

  6. Diversity and high nitrogenase activity of endophytic diazotrophs isolated from Oryza rufipogon Griff.

    Institute of Scientific and Technical Information of China (English)

    TAN ZhiYuan; PENG GuiXiang; XU PeiZhi; AI ShaoYing; TANG ShuanHu; ZHANG GuoXia; ZENG FengYun

    2009-01-01

    Diversity and nitrogenase activity of endophytic diazotrophs colonized in the wild rice Oryza rufipogon Griff grown in Boluo,Huilai County in Guangdong Province and Lingshui County in Hainan Province were studied.Thirty-seven isolates obtained from Oryza rufipogon were identified as putative endophytic nitrogen-fixing bacteria by ARA (acetylene reduction assay) test and further confirmed by PCR amplification of nifH gene fragments.All obtained strains have ARA activity and the same sized nifH gene fragments.Above the similarity level of 80%,the obtained isolates were assigned as Group Ⅰ to Ⅷ by the clustering of IS-PCR fingerprints.The SDS-PAGE whole-cell protein patterns were similar to those of IS-PCR fingerprints.Components and contents of fatty acid methyl esters (FAMEs) were used to differentiate the representative strains (Ls13,Ls8,BL1,BL12,HL6,Ls4) from Group Ⅰ to Group Ⅵ.The six representative strains showed significant difference in contents and components of cellular fatty acid methyl ester.16S rDNA sequencing analysis showed that strains of Group Ⅰ to Ⅶ were located in Enterobacteraceae (γ-proteobacteria).Strains of Group Ⅰ and Group Ⅱ were closely related to Klebsiella sp.;Strain Ls8 of Group Ⅱ was a little far away from the genus of Pantoea (homology level 96% with Pantoea agglomerans),which may represent a new species or genus in Enterobacteraceae;Strains of Groups Ⅳ and Ⅴ belonged to different Enterobacter sp.;Strain Ls4 and Ls 9 representing Group Ⅵ were close to Citrobacter amalonaticus with 98% sequence similarity;Strain Ls15 of Group Ⅶ showed 98% sequence identity with Pantoea sp.;Strains of Group Ⅷ were assigned to the genus Ideonella (β-proteobacteria).Based on the above results,endophytic diazotrophs isolated from O.rufipogon showed great diversity and some diazotrophs showed high nitrogenase activity with 42.52 μmol/mL·h C2H4.Inoculation to rice testa indicated that the isolated endophytic diazotrophs

  7. Draft Genome Sequence of Raoultella terrigena R1Gly, a Diazotrophic Endophyte.

    Science.gov (United States)

    Schicklberger, M; Shapiro, N; Loqué, D; Woyke, T; Chakraborty, R

    2015-06-11

    Raoultella terrigena R1Gly is a diazotrophic endophyte isolated from surface-sterilized roots of Nicotiana tabacum. The whole-genome sequence was obtained to investigate the endophytic characteristics of this organism at the genetic level, as well as to compare this strain with its close relatives. To our knowledge, this is the first genome obtained from the Raoultella terrigena species and only the third genome from the Raoultella genus, after Raoultella ornitholytic and Raoultella planticola. This genome will provide a foundation for further comparative genomic, metagenomic, and functional studies of this genus.

  8. Isolation and characterization of plant growth promoting endophytic diazotrophic bacteria from Korean rice cultivars.

    Science.gov (United States)

    Ji, Sang Hye; Gururani, Mayank Anand; Chun, Se-Chul

    2014-01-20

    We have isolated 576 endophytic bacteria from the leaves, stems, and roots of 10 rice cultivars and identified 12 of them as diazotrophic bacteria using a specific primer set of nif gene. Through 16S rDNA sequence analysis, nifH genes were confirmed in the two species of Penibacillus, three species of Microbacterium, three Bacillus species, and four species of Klebsiella. Rice seeds treated with these plant growth-promoting bacteria (PGPB) showed improved plant growth, increased height and dry weight and antagonistic effects against fungal pathogens. In addition, auxin and siderophore producing ability, and phosphate solubilizing activity were studied for the possible mechanisms of plant growth promotion. Among 12 isolates tested, 10 strains have shown higher auxin producing activity, 6 isolates were confirmed as strains with high siderophore producing activity while 4 isolates turned out to have high phosphate-solubilizing activity. These results strongly suggest that the endophytic diazotrophic bacteria characterized in this study could be successfully used to promote plant growth and inducing fungal resistance in plants.

  9. Natural association of Gluconacetobacter diazotrophicus and diazotrophic Acetobacter peroxydans with wetland rice.

    Science.gov (United States)

    Muthukumarasamy, Ramachandran; Cleenwerck, Ilse; Revathi, Gopalakrishnan; Vadivelu, Muthaiyan; Janssens, D; Hoste, B; Gum, Kang Ui; Park, Ki-Do; Son, Cho Young; Sa, Tongmin; Caballero-Mellado, Jesus

    2005-04-01

    The family Acetobacteraceae currently includes three known nitrogen-fixing species, Gluconacetobacter diazotrophicus, G. johannae and G. azotocaptans. In the present study, acetic acid-producing nitrogen-fixing bacteria were isolated from four different wetland rice varieties cultivated in the state of Tamilnadu, India. Most of these isolates were identified as G. diazotrophicus on the basis of their phenotypic characteristics and PCR assays using specific primers for that species. Based on 16S rDNA partial sequence analysis and DNA: DNA reassociation experiments the remaining isolates were identified as Acetobacter peroxydans, another species of the Acetobacteraceae family, thus far never reported as diazotrophic. The presence of nifH genes in A. peroxydans was confirmed by PCR amplification with nifH specific primers. Scope for the findings: This is the first report of the occurrence and association of N2-fixing Gluconacetobacter diazotrophicus and Acetobacter peroxydans with wetland rice varieties. This is the first report of diazotrophic nature of A. peroxydans.

  10. PHYTOLECTINS AND DIAZOTROPHS ARE THE POLYFUNCTIONAL COMPONENTS OF THE COMPLEX BIOLOGICAL COMPOSITIONS

    Directory of Open Access Journals (Sweden)

    Kyrychenko E. V.

    2014-02-01

    Full Text Available The role of lectins and diazotrophic microorganisms as polyfunctional components for creation of new lectin-bacterial biological composition with a view to practical application of agro biotechnology were discussed on the base of literature data and personal author’s experimental results. Phytolectins characterized by varied biological activity such as bioeffector, adap togen, growth-regulatory, fungicide and com munication to the components of a system «plant–soil–microorganisms» in molecular, cellular, organism and systemic levels of organization and functioning of agrophytocenosis. Rhizobacteria have many positive effects on plants and soil, the most determinative among the effects are the ability to fix molecular nitrogen of atmosphere, synthesis of hormonal and antibiotical substances, mobilization of sparingly soluble soil phosphates and decomposition of hazardous chemical compounds. It was justified creation of a new class of lectin-bacterial compositions on a base of phytolectins and diazotrophic microorganisms for increasing of productive potential of symbioses and associations, adaptable plasticity and plants protection and soil ecology improvement as well.

  11. Possible association of diazotrophs with marine zooplankton in the Pacific Ocean.

    Science.gov (United States)

    Azimuddin, Kazi Md; Hirai, Junya; Suzuki, Shotaro; Haider, Md Nurul; Tachibana, Aiko; Watanabe, Keigo; Kitamura, Minoru; Hashihama, Fuminori; Takahashi, Kazutaka; Hamasaki, Koji

    2016-12-01

    Dinitrogen fixation, the biological reduction in N2 gas to ammonia contributes to the supply of new nitrogen in the surface ocean. To understand the diversity and abundance of potentially diazotrophic (N2 fixing) microorganisms associated with marine zooplankton, especially copepods, the nifH gene was studied using zooplankton samples collected in the Pacific Ocean. In total, 257 nifH sequences were recovered from 23 nifH-positive DNA extracts out of 90 copepod samples. The nifH genes derived from cyanobacteria related to Trichodesmium, α- and γ-subdivisions of proteobacteria, and anaerobic euryarchaeota related to Methanosaeta concilii were detected. Our results indicated that Pleuromamma, Pontella, and Euchaeta were the major copepod genera hosting dinitrogen fixers, though we found no species-specific association between copepods and dinitrogen fixers. Also, the digital PCR provided novel data on the number of copies of the nifH gene in individual copepods, which we report the range from 30 to 1666 copies per copepod. This study is the first systematic study of zooplankton-associated diazotrophs, covering a large area of the open ocean, which provide a clue to further study of a possible new hotspot of N2 fixation. © 2016 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  12. Diazotrophic potential among bacterial communities associated with wild and cultivated Agave species.

    Science.gov (United States)

    Desgarennes, Damaris; Garrido, Etzel; Torres-Gomez, Miryam J; Peña-Cabriales, Juan J; Partida-Martinez, Laila P

    2014-12-01

    Agaves are major biotic resources in arid and semi-arid ecosystems. Despite their ecological, economical and cultural relevance, many aspects of the microbial communities associated with agaves are still unknown. Here, we investigated the bacterial communities associated with two Agave species by 16S rRNA- Denaturing gradient gel electrophoresis fingerprinting and sequencing. We also evaluated the effects of biotic and abiotic factors in the structure of the bacterial communities. In parallel, we isolated and characterized diazotrophic bacteria associated with agaves, as Agave soils are characterized by their low nitrogen content. Our results demonstrate that in Agave, the structure of prokaryotic assemblages was mostly influenced by the community group, where the soil, episphere, and endosphere were clearly distinct. Proteobacteria (γ and α), Actinobacteria, and Acidobacteria were the dominant phyla. Bacterial communities in the episphere of agaves were mainly influenced by the host species, whereas in the endosphere were affected by the season. Fifteen bacterial taxa were common and abundant in the endosphere of both Agave species during the dry season. Notably, some of the confirmed diazotrophic strains belonged to this group, suggesting a possible beneficial role in planta.

  13. Toxicity of herbicides used in the sugarcane crop to diazotrophic bacterium Herbaspirillum seropedicae

    Directory of Open Access Journals (Sweden)

    Sergio de Oliveira Procópio

    2014-10-01

    Full Text Available The objective of this work was to identify herbicides used in the sugarcane crop that affects neither the growth, the development, of nor the process of biological nitrogen fixation (BNF by the diazotrophic bacterium Herbaspirillum seropedicae. Eighteen herbicides (paraquat, ametryne, tebuthiuron, amicarbazone, diuron, metribuzin, [hexazinone + diuron], [hexazinone + clomazone], clomazone, isoxaflutole, sulfentrazone, oxyfluorfen, imazapic, imazapyr, [trifloxysulfuron sodium + ametryne], glyphosate, MSMA e 2,4-D were tested in their respective commercial doses regarding their impact on the growth of the bacteria in liquid medium DIGs. For this, we determined the duration of lag phase, generation time and maximum cell density of H. seropedicae, calculated from optical density data obtained at regular intervals during the incubation of cultures for 33 h at 32oC. We also evaluated the impact of herbicides on nitrogenase activity of H. seropedicae grown in semi-solid N-free JNFb medium. The effects of herbicides on the growth variables and the ARA were compared with the untreated control by Dunnett test. A completely randomized design was used. The herbicides paraquat, imazapyr, ametryne, glyphosate and oxyfluorfen inhibited the growth of H. seropedicae in vitro. Ametryne, oxyfluorfen and glyphosate caused a small reduction in the duration of the lag phase of diazotrophic bacteria H. seropedicae. Oxyfluorfen, ametryne and imazapyr resulted in increased the generation time by H. seropedicae. Glyphosate promoted drastic reduction in biological nitrogen fixation in vitro by H. seropedicae. The other tested herbicides did not affect the growth or the same BNF by H. seropedicae.

  14. Ecology and Physiology of the Pathogenic Cyanobacterium Roseofilum reptotaenium

    Directory of Open Access Journals (Sweden)

    Laurie L. Richardson

    2014-12-01

    Full Text Available Roseofilum reptotaenium is a gliding, filamentous, phycoerythrin-rich cyanobacterium that has been found only in the horizontally migrating, pathogenic microbial mat, black band disease (BBD on Caribbean corals. R. reptotaenium dominates the BBD mat in terms of biomass and motility, and the filaments form the mat fabric. This cyanobacterium produces the cyanotoxin microcystin, predominately MC-LR, and can tolerate high levels of sulfide produced by sulfate reducing bacteria (SRB that are also associated with BBD. Laboratory cultures of R. reptotaenium infect coral fragments, suggesting that the cyanobacterium is the primary pathogen of BBD, but since this species cannot grow axenically and Koch’s Postulates cannot be fulfilled, it cannot be proposed as a primary pathogen. However, R. reptotaenium does play several major pathogenic roles in this polymicrobial disease. Here, we provide an overview of the ecology of this coral pathogen and present new information on R. reptotaenium ecophysiology, including roles in the infection process, chemotactic and other motility responses, and the effect of pH on growth and motility. Additionally, we show, using metabolomics, that exposure of the BBD microbial community to the cyanotoxin MC-LR affects community metabolite profiles, in particular those associated with nucleic acid biosynthesis.

  15. Genotype × genotype interactions between the toxic cyanobacterium Microcystis and its grazer, the waterflea Daphnia

    Science.gov (United States)

    Lemaire, Veerle; Brusciotti, Silvia; van Gremberghe, Ineke; Vyverman, Wim; Vanoverbeke, Joost; De Meester, Luc

    2012-01-01

    Toxic algal blooms are an important problem worldwide. The literature on toxic cyanobacteria blooms in inland waters reports widely divergent results on whether zooplankton can control cyanobacteria blooms or cyanobacteria suppress zooplankton by their toxins. Here we test whether this may be due to genotype × genotype interactions, in which interactions between the large-bodied and efficient grazer Daphnia and the widespread cyanobacterium Microcystis are not only dependent on Microcystis strain or Daphnia genotype but are specific to genotype × genotype combinations. We show that genotype × genotype interactions are important in explaining mortality in short-time exposures of Daphnia to Microcystis. These genotype × genotype interactions may result in local coadaptation and a geographic mosaic of coevolution. Genotype × genotype interactions can explain why the literature on zooplankton–cyanobacteria interactions is seemingly inconsistent, and provide hope that zooplankton can contribute to the suppression of cyanobacteria blooms in restoration projects. PMID:25568039

  16. Complete Genome Sequence of Kosakonia sacchari Strain BO-1, an Endophytic Diazotroph Isolated from a Sweet Potato

    Science.gov (United States)

    Shinjo, Rina; Uesaka, Kazuma; Ihara, Kunio; Loshakova, Kseniia; Mizuno, Yuri; Yano, Katsuya

    2016-01-01

    The complete genome sequence of the endophytic diazotroph Kosakonia sacchari, isolated from a sweet potato, was analyzed. The 4,902,106-bp genome with 53.7% G+C content comprises 4,638 open reading frames, including nif genes, 84 tRNAs, and seven complete rRNAs in a circular chromosome. PMID:27609910

  17. Effect of salinity on nitrogenase activity and composition of the active diazotrophic community in intertidal microbial mats

    NARCIS (Netherlands)

    Severin, I.; Confurius-Guns, V.; Stal, L.J.

    2012-01-01

    Microbial mats are often found in intertidal areas experiencing a large range of salinities. This study investigated the effect of changing salinities on nitrogenase activity and on the composition of the active diazotrophic community (nifH transcript libraries) of three types of microbial mats situ

  18. Isolation and Screening of Bacteria for Their Diazotrophic Potential and Their Influence on Growth Promotion of Maize Seedlings in Greenhouses.

    Science.gov (United States)

    Kifle, Medhin H; Laing, Mark D

    2015-01-01

    Poor soil fertility is one of the major constraints for crop production. Nitrogen is the most limiting nutrient for increasing crop productivity. Therefore, there is a need to identify diazotrophic inoculants as an alternative or supplement to N-fertilizers for sustainable agriculture. In the current study, a number of free-living diazotrophic bacteria were isolated from soils collected from maize rhizosphere and from leaves and roots of maize within the KwaZulu-Natal Province, Republic of South Africa. Ninety-two isolates were selected for further screening because they were able to grow on N-free media containing different carbon sources. Isolates that were very slow to grow on N-free media were discarded. The isolates were screened in vitro for diazotrophic potential tests for ammonia production and acetylene reduction. Ethylene (C2H4) production was quantified and ranged from 4 to 73 nmoles of C2H4h(-1) culture(-1). The top 20 isolates were re-screened on maize seedlings, and eight isolates significantly (P = 0.001) enhanced some growth parameters of maize above the un-inoculated control. Isolates that showed significant effect on at least two growth parameters were identified at species or genera level. In conclusion, selected diazotrophic isolates may be potentially beneficial but they should be tested more in greenhouse and field conditions with maize to confirm their potential for application as biofertilizers.

  19. Isolation and screening of bacteria for their diazotrophic potential and their influence on growth promotion of maize seedlings in greenhouses

    Directory of Open Access Journals (Sweden)

    Medhin Hadish Kifle

    2016-01-01

    Full Text Available Poor soil fertility is one of the major constraints for crop production. Nitrogen is the most limiting nutrient for increasing crop productivity. Therefore, there is a need to identify diazotrophic inoculants as an alternative or supplement to N-fertilizers for sustainable agriculture. In the current study, a number of free-living diazotrophic bacteria were isolated from soils collected from maize rhizosphere and from leaves and roots of maize within the KwaZulu-Natal Province, Republic of South Africa. Ninety two isolates were selected for further screening because they were able to grow on N-free media containing different carbon sources. Isolates that were very slow to grow on N-free media were discarded. The isolates were screened in vitro for diazotrophic potential tests for ammonia production and acetylene reduction. Ethylene (C2H4 production was quantified and ranged from 4 to 73 nmoles of C2H4 h-1 culture-1. The top twenty isolates were re-screened on maize seedlings, and eight isolates significantly (P=0.001 enhanced some growth parameters of maize above the un-inoculated control. Isolates that showed significant effect on at least two growth parameters were identified at species or genera level. In conclusion, selected diazotrophic isolates may be potentially beneficial but they should be tested more in greenhouse and field conditions with maize to confirm their potential for application as biofertilizers.

  20. Effect of salinity on nitrogenase activity and composition of the active diazotrophic community in intertidal microbial mats

    NARCIS (Netherlands)

    Severin, I.; Confurius-Guns, V.; Stal, L.J.

    2012-01-01

    Microbial mats are often found in intertidal areas experiencing a large range of salinities. This study investigated the effect of changing salinities on nitrogenase activity and on the composition of the active diazotrophic community ( transcript libraries) of three types of microbial mats situated

  1. Effect of salinity on nitrogenase activity and composition of the active diazotrophic community in intertidal microbial mats

    NARCIS (Netherlands)

    Severin, I.; Confurius-Guns, V.; Stal, L.J.

    2012-01-01

    Microbial mats are often found in intertidal areas experiencing a large range of salinities. This study investigated the effect of changing salinities on nitrogenase activity and on the composition of the active diazotrophic community (nifH transcript libraries) of three types of microbial mats

  2. Use of endophytic diazotrophic bacteria as a vector to express the cry3A gene from Bacillus thuringiensis.

    NARCIS (Netherlands)

    Falcao Salles, Joana; Gitahy, P.M.; Skot, L.; Baldani, J.L.

    2000-01-01

    The goal of this study was to evaluate the potential of endophytic diazotrophic bacteria as a vector to express a cry gene from Bacillus thuringiensis, envisaging the control of pests that attack sugarcane plants. The endophytic nitrogen-fixing bacteria Gluconacetobacter diazotrophicus strain BR1128

  3. Biosynthesis of 130-kilodalton mosquito larvicide in the cyanobacterium Agmenellum quadruplicatum PR-6.

    OpenAIRE

    Angsuthanasombat, C; Panyim, S

    1989-01-01

    The 130-kilodalton mosquito larvicidal gene, cloned from Bacillus thuringiensis var. israelensis, was introduced into the cyanobacterium Agmenellum quadruplicatum PR-6 by plasmid transformation. Transformed cells synthesized 130-kilodalton delta-endotoxin protein and showed mosquito larvicidal activity. Results demonstrate a potential use of a cyanobacterium for biological control of mosquitoes.

  4. Biosynthesis of 130-kilodalton mosquito larvicide in the cyanobacterium Agmenellum quadruplicatum PR-6.

    Science.gov (United States)

    Angsuthanasombat, C; Panyim, S

    1989-09-01

    The 130-kilodalton mosquito larvicidal gene, cloned from Bacillus thuringiensis var. israelensis, was introduced into the cyanobacterium Agmenellum quadruplicatum PR-6 by plasmid transformation. Transformed cells synthesized 130-kilodalton delta-endotoxin protein and showed mosquito larvicidal activity. Results demonstrate a potential use of a cyanobacterium for biological control of mosquitoes.

  5. In silico differential display of defense-related expressed sequence tags from sugarcane tissues infected with diazotrophic endophytes

    Directory of Open Access Journals (Sweden)

    Lambais Marcio R.

    2001-01-01

    Full Text Available The expression patterns of 277 sugarcane expressed sequence tags (EST-contigs encoding putative defense-related (DR proteins were evaluated using the Sugarcane EST database. The DR proteins evaluated included chitinases, beta-1,3-glucanases, phenylalanine ammonia-lyases, chalcone synthases, chalcone isomerases, isoflavone reductases, hydroxyproline-rich glycoproteins, proline-rich glycoproteins, peroxidases, catalases, superoxide dismutases, WRKY-like transcription factors and proteins involved in cell death control. Putative sugarcane WRKY proteins were compared and their phylogenetic relationships determined. A hierarchical clustering approach was used to identify DR ESTs with similar expression profiles in representative cDNA libraries. To identify DR ESTs differentially expressed in sugarcane tissues infected with Gluconacetobacter diazotrophicus or Herbaspirillum rubrisubalbicans, 179 putative DR EST-contigs expressed in non-infected tissues (leaves and roots and/or infected tissues were selected and arrayed by similarity of their expression profiles. Changes in the expression levels of 124 putative DR EST-contigs, expressed in non-infected tissues, were evaluated in infected tissues. Approximately 42% of these EST-contigs showed no expression in infected tissues, whereas 15% and 3% showed more than 2-fold suppression in tissues infected with G. diazotrophicus or H. rubrisubalbicans, respectively. Approximately 14 and 8% of the DR EST-contigs evaluated showed more than 2-fold induction in tissues infected with G. diazotrophicus or H. rubrisubalbicans, respectively. The differential expression of clusters of DR genes may be important in the establishment of a compatible interaction between sugarcane and diazotrophic endophytes. It is suggested that the hierarchical clustering approach can be used on a genome-wide scale to identify genes likely involved in controlling plant-microorganism interactions.

  6. The marine diatom and diazotroph under future climate: Role of Iron

    Science.gov (United States)

    Li, Xuefeng; Fonseca-batista, Debany; Brouwers, Julie; Roevros, Nathalie; Dehairs, Frank; Chou, Lei

    2016-04-01

    Diatoms constitute a major group of phytoplankton, accounting for one quarter of the world's net primary productivity. Diazotrophs provide the largest input of new nitrogen (N) to the ocean and control the marine N budgets. It has been shown that iron (Fe) can be the limiting factor for diatom growth, in particular, in the HNLC (High Nutrient Low Chlorophyll) regions. This trace element can also govern the development of marine diazotrophs due to the high Fe demand necessary for biological N2 fixation. Iron plays thus an essential role in governing the marine primary productivity and the efficiency of biological carbon pump. Ocean systems are undergoing continuous modifications at varying rates and magnitudes as a result of changing climate. The objectives of our research is to evaluate 1) how climate change (dust deposition, ocean warming and acidification) can affect Fe biogeochemistry and the growth of diatoms and diazotrophs, and 2) the role of Fe in the control of biological N2 fixation under future climate scenarios. Laboratory culture experiments using Chaetoceros socialis were examined at two temperatures (13°C and 18°C) and two CO2 conditions (400 μatm and 800 μatm). The present study demonstrates clearly the influence of ocean acidification on the release of Fe upon dust deposition. It also shows that dust particles could provide a readily utilizable source of Fe and other macronutrients (dissolved phosphate and silicate) for phytoplankton growth. Elevated pCO2 concentrations may have adverse impact on the diatom growth; seawater warming may cause poleward shifts in the biogeographic distribution of diatoms. The impact of Fe on the natural N2 fixation was tested via field incubation experiments using natureal phytoplankton assemblage in the Bay of Biscay and along the Iberian Margin. N2 fixation rates in oligotrophic waters were greatly stimulated through the addition of dissolved Fe compared to the control, demonstrating the limitation of N2 fixation

  7. Utilization of a terrestrial cyanobacterium, Nostoc sp. HK-01, for space habitation

    Science.gov (United States)

    Kimura, Shunta; Tomita-Yokotani, Kaori; Arai, Mayumi; Yamashita, Masamichi; Katoh, Hiroshi; Ajioka, Reiko; Inoue, Kotomi

    2016-07-01

    A terrestrial cyanobacterium, Nostoc sp. HK-01 (hereafter HK-01), has several useful abilities for space habitation; photosynthesis, nitrogen fixation, and space environmental tolerances to vacuum, UV, gamma-ray, heavy particle beam, low and high temperature. Space environmental tolerances are important for transportation to Mars. HK-01 can grow on Martian regolith simulant (MRS) in vitro. Furthermore, HK-01 is useful as food. HK-01 may be utilized as oxygen supply, soil formation and food material for bio-chemical circulation in closed bio-ecosystems, including space habitation such as Mars. HK-01 was adopted as a biological material for the "TANPOPO" mission (JAXA et al.,), because of their high environmental tolerances. The "TANPOPO" mission is performing the space exposure experiments on the Japan Experimental Module (JEM) of the International Space Station (ISS). The results of these experiments will show the ability of HK-01 to survive in space.

  8. Designing and creating a modularized synthetic pathway in cyanobacterium Synechocystis enables production of acetone from carbon dioxide.

    Science.gov (United States)

    Zhou, Jie; Zhang, Haifeng; Zhang, Yanping; Li, Yin; Ma, Yanhe

    2012-07-01

    Ketones are a class of important organic compounds. As the simplest ketone, acetone is widely used as solvents or precursors for industrial chemicals. Presently, million tonnes of acetone is produced worldwide annually, from petrochemical processes. Here we report a biotechnological process that can produce acetone from CO(2), by designing and creating a modularized synthetic pathway in engineered cyanobacterium Synechocystis sp. PCC 6803. The engineered Synechocystis cells are able to produce acetone (36.0 mgl(-1) culture medium) using CO(2) as the sole carbon source, thus opens the gateway for biosynthesis of ketones from CO(2).

  9. Combined Effects of CO2 and Light on the N2-Fixing Cyanobacterium Trichodesmium IMS101: Physiological Responses1[OA

    Science.gov (United States)

    Kranz, Sven A.; Levitan, Orly; Richter, Klaus-Uwe; Prášil, Ondřej; Berman-Frank, Ilana; Rost, Björn

    2010-01-01

    Recent studies on the diazotrophic cyanobacterium Trichodesmium erythraeum (IMS101) showed that increasing CO2 partial pressure (pCO2) enhances N2 fixation and growth. Significant uncertainties remain as to the degree of the sensitivity to pCO2, its modification by other environmental factors, and underlying processes causing these responses. To address these questions, we examined the responses of Trichodesmium IMS101 grown under a matrix of low and high levels of pCO2 (150 and 900 μatm) and irradiance (50 and 200 μmol photons m−2 s−1). Growth rates as well as cellular carbon and nitrogen contents increased with increasing pCO2 and light levels in the cultures. The pCO2-dependent stimulation in organic carbon and nitrogen production was highest under low light. High pCO2 stimulated rates of N2 fixation and prolonged the duration, while high light affected maximum rates only. Gross photosynthesis increased with light but did not change with pCO2. HCO3− was identified as the predominant carbon source taken up in all treatments. Inorganic carbon uptake increased with light, but only gross CO2 uptake was enhanced under high pCO2. A comparison between carbon fluxes in vivo and those derived from 13C fractionation indicates high internal carbon cycling, especially in the low-pCO2 treatment under high light. Light-dependent oxygen uptake was only detected under low pCO2 combined with high light or when low-light-acclimated cells were exposed to high light, indicating that the Mehler reaction functions also as a photoprotective mechanism in Trichodesmium. Our data confirm the pronounced pCO2 effect on N2 fixation and growth in Trichodesmium and further show a strong modulation of these effects by light intensity. We attribute these responses to changes in the allocation of photosynthetic energy between carbon acquisition and the assimilation of carbon and nitrogen under elevated pCO2. These findings are supported by a complementary study looking at photosynthetic

  10. Effect of diazotrophic bacteria as phosphate solubilizing and indolic compound producers on maize plants

    Directory of Open Access Journals (Sweden)

    Mónica Del Pilar López Ortega

    2013-12-01

    Full Text Available Phosphorus is limiting for growth of maize plants, and because of that use of fertilizers like Rock Phosphate has been proposed. However, direct use of Rock Phosphate is not recommended because of its low availability, so it is necessary to improve it. In this study, a group of diazotrophic bacteria were evaluated as phosphate-solubilizing bacteria, for their production of indolic compounds and for their effects on growth of maize plants. Strains of the genera Azosporillum, Azotobacter, Rhizobium and Klebsiella, were quantitatively evaluated for solubilization of Ca3(PO42 and rock phosphate as a single source of phosphorous in SRS culture media. Additionally, the phosphatase enzyme activity was quantified at pH 5.0, 7.0 and 8.0 using p-nitrophenyl phosphate, and production of indolic compound was determined by colorimetric quantification. The effect of inoculation of bacteria on maize was determined in a completely randomized greenhouse experiment where root and shoot dry weights and phosphorus content were assessed. Results showed that strain C50 produced 107.2 mg .L-1 of available-P after 12 days of fermentation, and AC10 strain had the highest phosphatase activity at pH 8 with 12.7 mg of p-nitrophenol mL .h-1. All strains synthetized indolic compounds, and strain AV5 strain produced the most at 63.03 µg .mL-1. These diazotrophic bacteria increased plant biomass up to 39 % and accumulation of phosphorus by 10%. Hence, use of diazotrphic phosphate-solubilizing bacteria may represent an alternative technology for fertilization systems in maize plants.

  11. Nitrogen fixation (nif) genes of the cyanobacterium Anabaena species strain PCC 7120. The nifB-fdxN-nifS-nifU operon.

    Science.gov (United States)

    Mulligan, M E; Haselkorn, R

    1989-11-15

    A second nitrogen fixation (nif) operon in the cyanobacterium (blue-green alga) Anabaena (Nostoc) sp. strain PCC 7120 has been identified and sequenced. It is located just upstream of the nifHDK operon and consists of four genes in the order nifB, fdxN, nifS, and nifU. The three nif genes were identified on the basis of their similarity with the corresponding genes from other diazotrophs. The fourth gene, fdxN, codes for a bacterial type ferredoxin (Mulligan, M. E., Buikema, W. J., and Haselkorn, R. (1988) J. Bacteriol. 167, 4406-4410). The four genes are probably transcribed as a single operon, but are expressed at a lower level than the nifHDK operon, and only after a developmentally induced DNA rearrangement occurs that excises a 55-kilobase pair element from within the fdxN gene (Golden, J. W., Mulligan, M. E., and Haselkorn, R. (1987) Nature 327, 526-529; Golden, J. W., Carrasco, C. D., Mulligan, M. E., Schneider, G. J., and Haselkorn, R. (1988) J. Bacteriol. 170, 5034-5041). The promoter for the nifB operon was located by primer extension. Comparison of the nifB 5'-flanking sequence with the nifH 5'-flanking sequence did not reveal any consensus base pairs that would define a nif promoter for Anabaena. The operon contains two instances of 7-base pair directly repeated sequences: seven copies of the repeated sequence are found between the nifB and fdxN genes and six copies are found between the nifS and nifU genes. The function of these repeats is unknown.

  12. Shuttle cloning vectors for the cyanobacterium Anacystis nidulans.

    OpenAIRE

    Gendel, S; Straus, N; Pulleyblank, D; Williams, J

    1983-01-01

    Hybrid plasmids capable of acting as shuttle cloning vectors in Escherichia coli and the cyanobacterium Anacystis nidulans R2 were constructed by in vitro ligation. DNA from the small endogenous plasmid of A. nidulans was combined with two E. coli vectors, pBR325 and pDPL13, to create vectors containing either two selectable antibiotic resistance markers or a single marker linked to a flexible multisite polylinker. Nonessential DNA was deleted from the polylinker containing plasmid pPLAN B2 t...

  13. Diurnal Regulation of Cellular Processes in the Cyanobacterium Synechocystis sp. Strain PCC 6803: Insights from Transcriptomic, Fluxomic, and Physiological Analyses.

    Science.gov (United States)

    Saha, Rajib; Liu, Deng; Hoynes-O'Connor, Allison; Liberton, Michelle; Yu, Jingjie; Bhattacharyya-Pakrasi, Maitrayee; Balassy, Andrea; Zhang, Fuzhong; Moon, Tae Seok; Maranas, Costas D; Pakrasi, Himadri B

    2016-05-03

    Synechocystis sp. strain PCC 6803 is the most widely studied model cyanobacterium, with a well-developed omics level knowledgebase. Like the lifestyles of other cyanobacteria, that of Synechocystis PCC 6803 is tuned to diurnal changes in light intensity. In this study, we analyzed the expression patterns of all of the genes of this cyanobacterium over two consecutive diurnal periods. Using stringent criteria, we determined that the transcript levels of nearly 40% of the genes in Synechocystis PCC 6803 show robust diurnal oscillating behavior, with a majority of the transcripts being upregulated during the early light period. Such transcripts corresponded to a wide array of cellular processes, such as light harvesting, photosynthetic light and dark reactions, and central carbon metabolism. In contrast, transcripts of membrane transporters for transition metals involved in the photosynthetic electron transport chain (e.g., iron, manganese, and copper) were significantly upregulated during the late dark period. Thus, the pattern of global gene expression led to the development of two distinct transcriptional networks of coregulated oscillatory genes. These networks help describe how Synechocystis PCC 6803 regulates its metabolism toward the end of the dark period in anticipation of efficient photosynthesis during the early light period. Furthermore, in silico flux prediction of important cellular processes and experimental measurements of cellular ATP, NADP(H), and glycogen levels showed how this diurnal behavior influences its metabolic characteristics. In particular, NADPH/NADP(+) showed a strong correlation with the majority of the genes whose expression peaks in the light. We conclude that this ratio is a key endogenous determinant of the diurnal behavior of this cyanobacterium. Cyanobacteria are photosynthetic microbes that use energy from sunlight and CO2 as feedstock. Certain cyanobacterial strains are amenable to facile genetic manipulation, thus enabling

  14. NrrA directly regulates expression of the fraF gene and antisense RNAs for fraE in the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Ehira, Shigeki; Ohmori, Masayuki

    2014-05-01

    The heterocystous cyanobacterium Anabaena sp. strain PCC 7120 grows as linear multicellular filaments that can contain hundreds of cells. Heterocysts, which are specialized cells for nitrogen fixation, are regularly intercalated among photosynthetic vegetative cells, and these cells are metabolically dependent on each other. Thus, multicellularity is essential for diazotrophic growth of heterocystous cyanobacteria. In Anabaena sp. strain PCC 7120, the fraF gene, which is required to limit filament length, is induced by nitrogen deprivation. The fraF transcripts extend to the fraE gene, which lies on the opposite DNA strand and could possess dual functionality, mRNAs for fraF and antisense RNAs for fraE. In the present study, we found that NrrA, a nitrogen-regulated response regulator, directly regulated expression of fraF. Induction of fraF by nitrogen deprivation was abolished by the nrrA disruption. NrrA specifically bound to the promoter region of fraF, and recognized an inverted repeat sequence. Thus, it is concluded that NrrA controls expression of mRNAs for fraF and antisense RNAs for fraE in response to nitrogen deprivation.

  15. Diurnal Regulation of Cellular Processes in the Cyanobacterium Synechocystis sp. Strain PCC 6803: Insights from Transcriptomic, Fluxomic, and Physiological Analyses

    Directory of Open Access Journals (Sweden)

    Rajib Saha

    2016-05-01

    Full Text Available Synechocystis sp. strain PCC 6803 is the most widely studied model cyanobacterium, with a well-developed omics level knowledgebase. Like the lifestyles of other cyanobacteria, that of Synechocystis PCC 6803 is tuned to diurnal changes in light intensity. In this study, we analyzed the expression patterns of all of the genes of this cyanobacterium over two consecutive diurnal periods. Using stringent criteria, we determined that the transcript levels of nearly 40% of the genes in Synechocystis PCC 6803 show robust diurnal oscillating behavior, with a majority of the transcripts being upregulated during the early light period. Such transcripts corresponded to a wide array of cellular processes, such as light harvesting, photosynthetic light and dark reactions, and central carbon metabolism. In contrast, transcripts of membrane transporters for transition metals involved in the photosynthetic electron transport chain (e.g., iron, manganese, and copper were significantly upregulated during the late dark period. Thus, the pattern of global gene expression led to the development of two distinct transcriptional networks of coregulated oscillatory genes. These networks help describe how Synechocystis PCC 6803 regulates its metabolism toward the end of the dark period in anticipation of efficient photosynthesis during the early light period. Furthermore, in silico flux prediction of important cellular processes and experimental measurements of cellular ATP, NADP(H, and glycogen levels showed how this diurnal behavior influences its metabolic characteristics. In particular, NADPH/NADP+ showed a strong correlation with the majority of the genes whose expression peaks in the light. We conclude that this ratio is a key endogenous determinant of the diurnal behavior of this cyanobacterium.

  16. Expression of nifH genes by diazotrophic bacteria in the rhizosphere of short form Spartina alterniflora.

    Science.gov (United States)

    Brown, Michelle M; Friez, Michael J; Lovell, Charles R

    2003-04-01

    Abstract A diverse assemblage of diazotrophic bacteria exists in the rhizosphere of the smooth cordgrass, Spartina alterniflora, but the taxa actively involved in nitrogen fixation have not been determined. In order to identify the diazotrophs that were actively expressing nifH, the gene encoding the nitrogenase iron protein, mRNA was extracted from Spartina rhizosphere samples and nifH-specific seminested reverse transcriptase-PCR performed. Expressed nifH sequences were recovered from organisms affiliated with the (gamma-+beta-) Proteobacteria and the anaerobes. Most of the expressed nifH sequences were highly similar (>/=95% similarity) to sequences previously recovered from Spartina rhizosphere DNA using conventional nifH-specific PCR. These sequences were also similar, although not identical to the nifH sequences of Pseudomonas stutzeri, Vibrio diazotrophicus, Desulfovibrio africanus, and Desulfovibrio gigas.

  17. Biofilm comprising phototrophic, diazotrophic, and hydrocarbon-utilizing bacteria: a promising consortium in the bioremediation of aquatic hydrocarbon pollutants.

    Science.gov (United States)

    Al-Bader, Dhia; Kansour, Mayada K; Rayan, Rehab; Radwan, Samir S

    2013-05-01

    Biofilms harboring simultaneously anoxygenic and oxygenic phototrophic bacteria, diazotrophic bacteria, and hydrocarbon-utilizing bacteria were established on glass slides suspended in pristine and oily seawater. Via denaturing gradient gel electrophoresis analysis on PCR-amplified rRNA gene sequence fragments from the extracted DNA from biofilms, followed by band amplification, biofilm composition was determined. The biofilms contained anoxygenic phototrophs belonging to alphaproteobacteria; pico- and filamentous cyanobacteria (oxygenic phototrophs); two species of the diazotroph Azospirillum; and two hydrocarbon-utilizing gammaproteobacterial genera, Cycloclasticus and Oleibacter. The coexistence of all these microbial taxa with different physiologies in the biofilm makes the whole community nutritionally self-sufficient and adequately aerated, a condition quite suitable for the microbial biodegradation of aquatic pollutant hydrocarbons.

  18. Effect of salinity on nitrogenase activity and composition of the active diazotrophic community in intertidal microbial mats

    OpenAIRE

    Severin, I.; Confurius-Guns, V.; Stal, L.J.

    2012-01-01

    Microbial mats are often found in intertidal areas experiencing a large range of salinities. This study investigated the effect of changing salinities on nitrogenase activity and on the composition of the active diazotrophic community (nifH transcript libraries) of three types of microbial mats situated along a littoral gradient. All three mat types exhibited highest nitrogenase activity at salinities close to ambient seawater or lower. The response to lower or higher salinity was strongest i...

  19. Effect of salinity on nitrogenase activity and composition of the active diazotrophic community in intertidal microbial mats

    OpenAIRE

    2012-01-01

    Microbial mats are often found in intertidal areas experiencing a large range of salinities. This study investigated the effect of changing salinities on nitrogenase activity and on the composition of the active diazotrophic community (nifH transcript libraries) of three types of microbial mats situated along a littoral gradient. All three mat types exhibited highest nitrogenase activity at salinities close to ambient seawater or lower. The response to lower or higher salinity was strongest i...

  20. Endophytic colonization of rice (Oryza sativa L.) by the diazotrophic bacterium Burkholderia kururiensis and its ability to enhance plant growth

    OpenAIRE

    Mattos, Katherine A; Vania L.M. Pádua; Alexandre Romeiro; Hallack,Leticia F.; Bianca C. Neves; Tecia M.U. Ulisses; Claudia F. Barros; Adriane R Todeschini; Previato, José O.; Lucia Mendonça-Previato

    2008-01-01

    Burkholderia kururiensis is a diazotrophic bacterium originally isolated from a polluted aquifer environment and presents a high level of similarity with the rice endophyte "B. brasilensis" species. This work assessed the ability of B. kururiensis to endophytically colonize rice plantlets by monitoring different tissues of root-inoculated plants for the presence of bacterial growth in different media, electron microscopy and by 16S rDNA analysis. Observations of roots, stems and leaves of ino...

  1. Screening and selection of most potent diazotrophic cyanobacterial isolate exhibiting natural tolerance to rice field herbicides for exploitation as biofertilizer.

    Science.gov (United States)

    Singh, Surendra; Datta, Pallavi

    2006-01-01

    Periodic applications of heavy dosages of herbicides in modern rice-agriculture are a necessary evil for obtaining high crop productivity. Such herbicides are not only detrimental to weeds but biofertilizer strains of diazotrophic cyanobacteria also. It is therefore, essential to screen and select such biofertilizer strains of diazotrophic cyanobacteria exhibiting natural tolerance to common rice-field herbicides that can be further improved by mutational techniques to make biofertilizer technology a viable one. Therefore, efforts have been made to screen five dominant diazotrophic cyanobacterial forms e.g. filamentous heterocystous Nostoc punctiforme , Nostoc calcicola , Anabaena variabilis and unicellular Gloeocapsa sp. and Aphanocapsa sp. along with standard laboratory strain Nostoc muscorum ISU against increasing concentrations (0-100 mg l(-1) of four commercial grade common rice-field herbicides i.e. Arozin, Butachlor, Alachlor and 2,4-D under diazotrophic growth conditions. The lethal and IGC(50) concentrations for all four herbicides tested were found highest for A. variabilis as compared to other test cyanobacteria. The lowest reduction in chlorophyll a content, photosynthetic oxygen evolution, and N(2)-fixation was found in A. variabilis as compared to other rice field isolates and standard laboratory strain N. muscorum ISU. On the basis of prolong survival potential and lowest reductions in vital metabolic activities tested at IGC(50) concentration of four herbicides, it is concluded that A. variabilis is the most potent and promising cyanobacterial isolate as compared with other forms. This could be further improved by mutational techniques for exploitation as most potential and viable biofertilizer strain.

  2. Characterization of plant-growth promoting diazotrophic bacteria isolated from field grown Chinese cabbage under different fertilization conditions.

    Science.gov (United States)

    Yim, Woo-Jong; Poonguzhali, Selvaraj; Madhaiyan, Munusamy; Palaniappan, Pitchai; Siddikee, M A; Sa, Tongmin

    2009-04-01

    Diazotrophic bacteria isolated from the rhizosphere of Chinese cabbage were assessed for other plant growth promoting characteristics viz., production of IAA, ethylene, ACC deaminase, phosphate solubilization, and gnotobiotic root elongation. Their effect on inoculation to Chinese cabbage was also observed under growth chamber conditions. A total of 19 strains that showed higher nitrogenase activity identified by 16S rRNA gene sequence analysis were found to be the members of the genera Pseudomonas and Agrobacterium belonging to alpha- and gamma-Proteobacteria groups. These strains were also efficient in producing IAA and ACC deaminase though they produced low levels of ethylene and no phosphate solubilization. In addition, inoculation of selected diazotrophic bacterial strains significantly increased seedling length, dry weight, and total nitrogen when compared to uninoculated control. The colonization of crop plants by diazotrophic bacteria can be affected by many biotic and abiotic factors, and further studies are oriented towards investigating the factors that could influence the establishment of a selected bacterial community.

  3. Associative diazotrophic bacteria in grass roots and soils from heavy metal contaminated sites

    Directory of Open Access Journals (Sweden)

    Fátima M.S. Moreira

    2008-12-01

    Full Text Available This work aimed to evaluate density of associative diazotrophic bacteria populations in soil and grass root samples from heavy metal contaminated sites, and to characterize isolates from these populations, both, phenotypically (Zinc, Cadmium and NaCl tolerance in vitro, and protein profiles and genotypically (16S rDNA sequencing, as compared to type strains of known diazotrophic species. Densities were evaluated by using NFb, Fam and JNFb media, commonly used for enrichment cultures of diazotrophic bacteria. Bacterial densities found in soil and grass root samples from contaminated sites were similar to those reported for agricultural soils. Azospirillum spp. isolates from contaminated sites and type strains from non-contaminated sites varied substantially in their in vitro tolerance to Zn+2 and Cd+2, being Cd+2 more toxic than Zn+2. Among the most tolerant isolates (UFLA 1S, 1R, S181, S34 and S22, some (1R, S34 and S22 were more tolerant to heavy metals than rhizobia from tropical and temperate soils. The majority of the isolates tolerant to heavy metals were also tolerant to salt stress as indicated by their ability to grow in solid medium supplemented with 30 g L-1 NaCl. Five isolates exhibited high dissimilarity in protein profiles, and the 16S rDNA sequence analysis of two of them revealed new sequences for Azospirillum.Objetivou-se avaliar a densidade de populações de bactérias diazotróficas associativas em amostras de solos e de raízes de gramíneas oriundas de sítios contaminados com metais pesados, e caracterizar isolados destas populações através da análise fenotípica (tolerância aos metais pesados zinco e cádmio e à NaCl in vitro, perfis protéicos, e genotípica (seqüenciamento de 16S rDNA, comparados às estirpes tipo das mesmas espécies. As densidades foram avaliadas nos meios NFb, Fam e LGI, comumente utilizados para culturas de enriquecimento de populações de bactérias diazotróficas associativas. As densidades

  4. Effect of Selected Plant Extracts and D- and L-Lysine on the Cyanobacterium Microcystis aeruginosa

    National Research Council Canada - National Science Library

    Lurling, M; Van Oosterhout, F

    2014-01-01

    We tested extracts from Fructus mume, Salvia miltiorrhiza and Moringa oleifera as well as L-lysine and D-Lysine as curative measures to rapidly suppress the cyanobacterium Microcystis aeruginosa NIVA-CYA 43...

  5. Cyanobacterium sp. host cell and vector for production of chemical compounds in Cyanobacterial cultures

    Energy Technology Data Exchange (ETDEWEB)

    Piven, Irina; Friedrich, Alexandra; Duhring, Ulf; Uliczka, Frank; Baier, Kerstin; Inaba, Masami; Shi, Tuo; Wang, Kui; Enke, Heike; Kramer, Dan

    2016-04-19

    A cyanobacterial host cell, Cyanobacterium sp., that harbors at least one recombinant gene for the production of a chemical compounds is provided, as well as vectors derived from an endogenous plasmid isolated from the cell.

  6. Mössbauer study of cobalt and iron in the cyanobacterium (blue green alga)

    Science.gov (United States)

    Ambe, Shizuko

    1990-07-01

    Mössbauer emission and absorption studies have been performed on cobalt and iron in the cyanobacterium (blue-green alga). The Mössbauer spectrum of the cyanobacterium cultivated with57Co is decomposed into two doublets. The parameters of the major doublet are in good agreement with those of cyanocobalamin (vitamin B12) labeled with57Co. The other minor doublet has parameters close to those of Fe(II) coordinated with six nitrogen atoms. These suggest that cobalt is used for the biosynthesis of vitamin B12 or its analogs in the cyanobacterium. The spectra of the cyanobacterium grown with57Fe show that iron is in the high-spin trivalent state and possibly in the form of ferritin, iron storage protein.

  7. Novel surface associated polyphosphate bodies sequester uranium in the filamentous, marine cyanobacterium, Anabaena torulosa.

    Science.gov (United States)

    Acharya, Celin; Apte, Shree Kumar

    2013-12-01

    A filamentous, heterocystous, nitrogen-fixing marine cyanobacterium, Anabaena torulosa, has been shown to harbour surface associated, acid soluble polyphosphate bodies. Uranium immobilization by such polyphosphate bodies, reported in cyanobacteria for the first time, demonstrates a novel uranium sequestration phenomenon.

  8. Cyanobacterium sp. host cell and vector for production of chemical compounds in cyanobacterial cultures

    Science.gov (United States)

    Piven, Irina; Friedrich, Alexandra; Duhring, Ulf; Uliczka, Frank; Baier, Kerstin; Inaba, Masami; Shi, Tuo; Wang, Kui; Enke, Heike; Kramer, Dan

    2014-09-30

    A cyanobacterial host cell, Cyanobacterium sp., that harbors at least one recombinant gene for the production of a chemical compounds is provided, as well as vectors derived from an endogenous plasmid isolated from the cell.

  9. Alkane production by the marine cyanobacterium Synechococcus sp. NKBG15041c possessing the α-olefin biosynthesis pathway.

    Science.gov (United States)

    Yoshino, Tomoko; Liang, Yue; Arai, Daichi; Maeda, Yoshiaki; Honda, Toru; Muto, Masaki; Kakunaka, Natsumi; Tanaka, Tsuyoshi

    2015-02-01

    The production of alkanes in a marine cyanobacterium possessing the α-olefin biosynthesis pathway was achieved by introducing an exogenous alkane biosynthesis pathway. Cyanobacterial hydrocarbons are synthesized via two separate pathways: the acyl-acyl carrier protein (ACP) reductase/aldehyde-deformylating oxygenase (AAR/ADO) pathway for the alkane biosynthesis and the α-olefin synthase (OLS) pathway for the α-olefin biosynthesis. Coexistence of these pathways has not yet been reported. In this study, the marine cyanobacterium Synechococcus sp. NKBG15041c was shown to produce α-olefins similar to those of Synechococcus sp. PCC7002 via the α-olefin biosynthesis pathway. The production of heptadecane in Synechococcus sp. NKBG15041c was achieved by expressing the AAR/ADO pathway genes from Synechococcus elongatus PCC 7942. The production yields of heptadecane in Synechococcus sp. NKBG15041c varied with the expression level of the aar and ado genes. The maximal yield of heptadecane was 4.2 ± 1.2 μg/g of dried cell weight in the transformant carrying a homologous promoter. Our results also suggested that the effective activation of ADO may be more important for the enhancement of alkane production by cyanobacteria.

  10. INOCULATION OF DIAZOTROPHIC BACTERIA AND NITROGEN FERTILIZATION IN TOPDRESSING IN IRRIGATED CORN

    Directory of Open Access Journals (Sweden)

    VANESSA ZIRONDI LONGHINI

    2016-01-01

    Full Text Available Corn is a nitrogen-intensive crop, and the use of management practices such as inoculation of the seed with diazotrophic bacteria, which can maximize crop productivity and reduce the need of nitrogen fertilizers, may result in lower production costs. The present study aimed to evaluate the effect of inoculation of corn seed with Azospirillum brasilense and controlled addition of nitrogen to topdressing on the nutrition, production components, and productivity of crop grain. The experimental design was a randomized block design, with four replications in a 2 × 5 factorial scheme. The treatments consisted of inoculation or not of corn seed with A. brasilense (at 100 mL per 25 kg of seed and five nitrogen (N levels in topdressing (0, 30, 60, 90, and 120 kg N ha-1 from urea [45% N] were applied when the corn was in the phenological growth stage V6. Foliar macronutrients, foliar chlorophyll index (FCI, production components, and yield of corn grain were valuated. Inoculation of corn seeds with A. brasilense increased plant height and grain yield. Fertilization in topdressing, with N levels up to 120 kg ha-1, linearly increased the foliar nutrients and productivity of corn cultivated in the spring/summer in the low-altitude Cerrado region of Brazil.

  11. Genome of Herbaspirillum seropedicae strain SmR1, a specialized diazotrophic endophyte of tropical grasses.

    Directory of Open Access Journals (Sweden)

    Fábio O Pedrosa

    2011-05-01

    Full Text Available The molecular mechanisms of plant recognition, colonization, and nutrient exchange between diazotrophic endophytes and plants are scarcely known. Herbaspirillum seropedicae is an endophytic bacterium capable of colonizing intercellular spaces of grasses such as rice and sugar cane. The genome of H. seropedicae strain SmR1 was sequenced and annotated by The Paraná State Genome Programme--GENOPAR. The genome is composed of a circular chromosome of 5,513,887 bp and contains a total of 4,804 genes. The genome sequence revealed that H. seropedicae is a highly versatile microorganism with capacity to metabolize a wide range of carbon and nitrogen sources and with possession of four distinct terminal oxidases. The genome contains a multitude of protein secretion systems, including type I, type II, type III, type V, and type VI secretion systems, and type IV pili, suggesting a high potential to interact with host plants. H. seropedicae is able to synthesize indole acetic acid as reflected by the four IAA biosynthetic pathways present. A gene coding for ACC deaminase, which may be involved in modulating the associated plant ethylene-signaling pathway, is also present. Genes for hemagglutinins/hemolysins/adhesins were found and may play a role in plant cell surface adhesion. These features may endow H. seropedicae with the ability to establish an endophytic life-style in a large number of plant species.

  12. Association with an ammonium-excreting bacterium allows diazotrophic culture of oil-rich eukaryotic microalgae.

    Science.gov (United States)

    Ortiz-Marquez, Juan Cesar Federico; Do Nascimento, Mauro; Dublan, Maria de Los Angeles; Curatti, Leonardo

    2012-04-01

    Concerns regarding the depletion of the world's reserves of oil and global climate change have promoted an intensification of research and development toward the production of biofuels and other alternative sources of energy during the last years. There is currently much interest in developing the technology for third-generation biofuels from microalgal biomass mainly because of its potential for high yields and reduced land use changes in comparison with biofuels derived from plant feedstocks. Regardless of the nature of the feedstock, the use of fertilizers, especially nitrogen, entails a potential economic and environmental drawback for the sustainability of biofuel production. In this work, we have studied the possibility of nitrogen biofertilization by diazotrophic bacteria applied to cultured microalgae as a promising feedstock for next-generation biofuels. We have obtained an Azotobacter vinelandii mutant strain that accumulates several times more ammonium in culture medium than wild-type cells. The ammonium excreted by the mutant cells is bioavailable to promote the growth of nondiazotrophic microalgae. Moreover, this synthetic symbiosis was able to produce an oil-rich microalgal biomass using both carbon and nitrogen from the air. This work provides a proof of concept that artificial symbiosis may be considered an alternative strategy for the low-N-intensive cultivation of microalgae for the sustainable production of next-generation biofuels and other bioproducts.

  13. Association with an Ammonium-Excreting Bacterium Allows Diazotrophic Culture of Oil-Rich Eukaryotic Microalgae

    Science.gov (United States)

    Ortiz-Marquez, Juan Cesar Federico; Do Nascimento, Mauro; Dublan, Maria de los Angeles

    2012-01-01

    Concerns regarding the depletion of the world's reserves of oil and global climate change have promoted an intensification of research and development toward the production of biofuels and other alternative sources of energy during the last years. There is currently much interest in developing the technology for third-generation biofuels from microalgal biomass mainly because of its potential for high yields and reduced land use changes in comparison with biofuels derived from plant feedstocks. Regardless of the nature of the feedstock, the use of fertilizers, especially nitrogen, entails a potential economic and environmental drawback for the sustainability of biofuel production. In this work, we have studied the possibility of nitrogen biofertilization by diazotrophic bacteria applied to cultured microalgae as a promising feedstock for next-generation biofuels. We have obtained an Azotobacter vinelandii mutant strain that accumulates several times more ammonium in culture medium than wild-type cells. The ammonium excreted by the mutant cells is bioavailable to promote the growth of nondiazotrophic microalgae. Moreover, this synthetic symbiosis was able to produce an oil-rich microalgal biomass using both carbon and nitrogen from the air. This work provides a proof of concept that artificial symbiosis may be considered an alternative strategy for the low-N-intensive cultivation of microalgae for the sustainable production of next-generation biofuels and other bioproducts. PMID:22267660

  14. Heterologous expression of an algal hydrogenase in a heterocystous cyanobacterium

    Energy Technology Data Exchange (ETDEWEB)

    Thorsten Heidorn; Peter Lindblad [Dept. of Physiological Botany, Uppsala University, Villavogen 6, SE-752 36 Uppsala, (Sweden)

    2006-07-01

    For the expression of an active algal [FeFe] hydrogenase in the heterocystous cyanobacterium Nostoc punctiforme A TCC 29133 the Chlamydomonas reinhardtii hydrogenase gene hydA1 and the accessory genes hydEF and hydG are to be introduced into the cyanobacteria cells. The genes were amplified by PCR from EST clones, cloned into the cloning vector pBluescript SK+ and sequenced. An expression vector for multi-cistronic cloning, based on pSCR202, was constructed and for a functional test GFP was inserted as a reporter gene. The GFP construct was transformed into Nostoc punctiforme A TCC 29133 by electroporation and expression of GFP was visualized by fluorescence microscopy. (authors)

  15. Genetic manipulation of a cyanobacterium for heavy metal detoxivication

    Energy Technology Data Exchange (ETDEWEB)

    McCormick, P.; Cannon, G.; Heinhorst, S.

    1995-12-31

    Increasing heavy metal contamination of soil and water has produced a need for economical and effective methods to reduce toxic buildup of these materials. Biological systems use metallothionein proteins to sequester such metals as Cu, Cd, and Zn. Studies are underway to genetically engineer a cyanobacteria strain with increased ability for metallothionein production and increased sequestration capacity. Cyanobacteria require only sunlight and CO{sub 2}. Vector constructs are being developed in a naturally competent, unicellular cyanobacterium Anacystis nidulans R2. Closed copies of a yeast copper metallothionein gene have been inserted into a cyanobacterial shuttle vector as well as a vector designed for genomic integration. Transformation studies have produced recombinant cyanobacteria from both of these systems, and work is currently underway to assess the organism`s ability to withstand increasing Cu, Cd, and Zn concentrations.

  16. The effect of oxygen concentration and temperature on nitrogenase activity in the heterocystous cyanobacterium

    NARCIS (Netherlands)

    Stal, L.

    2017-01-01

    Heterocysts are differentiated cells formed by some filamentous, diazotrophic (dinitrogen-fixing)cyanobacteria. The heterocyst is the site of dinitrogen fixation providing the oxygen-sensitivenitrogenase with a low-oxygen environment. The diffusion of air into the heterocyst is a compromisebetween t

  17. Sustained H(2) production driven by photosynthetic water splitting in a unicellular cyanobacterium.

    Science.gov (United States)

    Melnicki, Matthew R; Pinchuk, Grigoriy E; Hill, Eric A; Kucek, Leo A; Fredrickson, Jim K; Konopka, Allan; Beliaev, Alexander S

    2012-01-01

    The relationship between dinitrogenase-driven H(2) production and oxygenic photosynthesis was investigated in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142, using a novel custom-built photobioreactor equipped with advanced process control. Continuously illuminated nitrogen-deprived cells evolved H(2) at rates up to 400 µmol ⋅ mg Chl(-1) ⋅ h(-1) in parallel with uninterrupted photosynthetic O(2) production. Notably, sustained coproduction of H(2) and O(2) occurred over 100 h in the presence of CO(2), with both gases displaying inverse oscillations which eventually dampened toward stable rates of 125 and 90 µmol ⋅ mg Chl(-1) ⋅ h(-1), respectively. Oscillations were not observed when CO(2) was omitted, and instead H(2) and O(2) evolution rates were positively correlated. The sustainability of the process was further supported by stable chlorophyll content, maintenance of baseline protein and carbohydrate levels, and an enhanced capacity for linear electron transport as measured by chlorophyll fluorescence throughout the experiment. In situ light saturation analyses of H(2) production displayed a strong dose dependence and lack of O(2) inhibition. Inactivation of photosystem II had substantial long-term effects but did not affect short-term H(2) production, indicating that the process is also supported by photosystem I activity and oxidation of endogenous glycogen. However, mass balance calculations suggest that carbohydrate consumption in the light may, at best, account for no more than 50% of the reductant required for the corresponding H(2) production over that period. Collectively, our results demonstrate that uninterrupted H(2) production in unicellular cyanobacteria can be fueled by water photolysis without the detrimental effects of O(2) and have important implications for sustainable production of biofuels. The study provides an important insight into the photophysiology of light-driven H(2) production by the nitrogen-fixing cyanobacterium

  18. Biogeochemical fluxes and fate of diazotroph-derived nitrogen in the food web after a phosphate enrichment: modeling of the VAHINE mesocosms experiment

    Science.gov (United States)

    Gimenez, Audrey; Baklouti, Melika; Bonnet, Sophie; Moutin, Thierry

    2016-09-01

    The VAHINE mesocosm experiment in the oligotrophic waters of the Nouméa lagoon (New Caledonia), where high N2 fixation rates and abundant diazotroph organisms were observed, aimed to assess the role of the nitrogen input through N2 fixation in carbon production and export and to study the fate of diazotroph-derived nitrogen (DDN) throughout the planktonic food web. A 1-D vertical biogeochemical mechanistic model was used in addition to the in situ experiment to enrich our understanding of the dynamics of the planktonic ecosystem and the main biogeochemical carbon (C), nitrogen (N) and phosphate (P) fluxes. The mesocosms were intentionally enriched with ˜ 0.8 µmol L-1 of inorganic P to trigger the development of diazotrophs and amplify biogeochemical fluxes. Two simulations were run, one with and the other without the phosphate enrichment. In the P-enriched simulation, N2 fixation, primary production (PP) and C export increased by 201, 208 and 87 %, respectively, consistent with the trends observed in the mesocosms (+124, +141 and +261 % for N2 fixation, PP and C export, respectively). In total, 5-10 days were necessary to obtain an increase in primary and export productions after the dissolved inorganic phosphate (DIP) enrichment, thereby suggesting that classical methods (short-term microcosms experiments) used to quantify nutrient limitations of primary production may not be relevant. The model enabled us to monitor the fate of fixed N2 by providing the proportion of DDN in each compartment (inorganic and organic) of the model over time. At the end of the simulation (25 days), 43 % of the DDN was found in the non-diazotroph organisms, 33 % in diazotrophs, 16 % in the dissolved organic nitrogen pool, 3 % in the particulate detrital organic pool and 5 % in traps, indicating that N2 fixation was of benefit to non-diazotrophic organisms and contributed to C export.

  19. Phosphoproteome of the cyanobacterium Synechocystis sp. PCC 6803 and its dynamics during nitrogen starvation.

    Science.gov (United States)

    Spät, Philipp; Maček, Boris; Forchhammer, Karl

    2015-01-01

    Cyanobacteria have shaped the earth's biosphere as the first oxygenic photoautotrophs and still play an important role in many ecosystems. The ability to adapt to changing environmental conditions is an essential characteristic in order to ensure survival. To this end, numerous studies have shown that bacteria use protein post-translational modifications such as Ser/Thr/Tyr phosphorylation in cell signaling, adaptation, and regulation. Nevertheless, our knowledge of cyanobacterial phosphoproteomes and their dynamic response to environmental stimuli is relatively limited. In this study, we applied gel-free methods and high accuracy mass spectrometry toward the detection of Ser/Thr/Tyr phosphorylation events in the model cyanobacterium Synechocystis sp. PCC 6803. We could identify over 300 phosphorylation events in cultures grown on nitrate as exclusive nitrogen source. Chemical dimethylation labeling was applied to investigate proteome and phosphoproteome dynamics during nitrogen starvation. Our dataset describes the most comprehensive (phospho)proteome of Synechocystis to date, identifying 2382 proteins and 183 phosphorylation events and quantifying 2111 proteins and 148 phosphorylation events during nitrogen starvation. Global protein phosphorylation levels were increased in response to nitrogen depletion after 24 h. Among the proteins with increased phosphorylation, the PII signaling protein showed the highest fold-change, serving as positive control. Other proteins with increased phosphorylation levels comprised functions in photosynthesis and in carbon and nitrogen metabolism. This study reveals dynamics of Synechocystis phosphoproteome in response to environmental stimuli and suggests an important role of protein Ser/Thr/Tyr phosphorylation in fundamental mechanisms of homeostatic control in cyanobacteria.

  20. Experimental assessment of diazotroph responses to elevated seawater pCO2 in the North Pacific Subtropical Gyre

    Science.gov (United States)

    Böttjer, Daniela; Karl, David M.; Letelier, Ricardo M.; Viviani, Donn A.; Church, Matthew J.

    2014-06-01

    We examined short-term (24-72 h) responses of naturally occurring marine N2 fixing microorganisms (termed diazotrophs) to abrupt increases in the partial pressure of carbon dioxide (pCO2) in seawater during nine incubation experiments conducted between May 2010 and September 2012 at Station ALOHA (A Long-term Oligotrophic Habitat Assessment) (22°45'N, 158°W) in the North Pacific Subtropical Gyre (NPSG). Rates of N2 fixation, nitrogenase (nifH) gene abundances and transcripts of six major groups of cyanobacterial diazotrophs (including both unicellular and filamentous phylotypes), and rates of primary productivity (as measured by 14C-bicarbonate assimilation into plankton biomass) were determined under contemporary (~390 ppm) and elevated pCO2 conditions (~1100 ppm). Quantitative polymerase chain reaction (QPCR) amplification of planktonic nifH genes revealed that unicellular cyanobacteria phylotypes dominated gene abundances during these experiments. In the majority of experiments (seven out of nine), elevated pCO2 did not significantly influence rates of dinitrogen (N2) fixation or primary productivity (two-way analysis of variance (ANOVA), P > 0.05). During two experiments, rates of N2 fixation and primary productivity were significantly lower (by 79 to 82% and 52 to 72%, respectively) in the elevated pCO2 treatments relative to the ambient controls (two-way ANOVA, P < 0.05). QPCR amplification of nifH genes and gene transcripts revealed that diazotroph abundances and nifH gene expression were largely unchanged by the perturbation of the seawater pCO2. Our results suggest that naturally occurring N2 fixing plankton assemblages in the NPSG are relatively resilient to large, short-term increases in pCO2.

  1. Effects of the inoculation of Burkholderia vietnamensis and related endophytic diazotrophic bacteria on grain yield of rice.

    Science.gov (United States)

    Govindarajan, Munusamy; Balandreau, Jacques; Kwon, Soon-Wo; Weon, Hang-Yeon; Lakshminarasimhan, Cunthipuram

    2008-01-01

    During a survey of endophytic diazotrophic bacteria associated with different rice varieties in Tamilnadu, some "endophytes" were obtained. Thirteen bacterial isolates from surface-sterilized roots and shoots were obtained in pure culture, which produced indole acetic acid (IAA) and reduced acetylene to ethylene. Polymerase chain reaction (PCR) amplification confirmed the presence of nif-H gene in all the isolates. Morphological, biochemical, and molecular characteristics indicated that all of them belonged to the genus Burkholderia One of them, MGK3, was consistently more active in reducing acetylene, and 16S rDNA sequences of isolate MGK3 confirmed its identification as Burkholderia vietnamiensis. Colonization of rice root was confirmed by strain MGK3 marked with gusA gene. The inoculated roots showed a blue color, which was most intense at the points of lateral root emergence and at the root tip. Transverse sections of roots, 15 days after inoculation, revealed beta-glucuronidase (GUS) activity within many of the cortical intercellular spaces next to the stele and within the aerenchyma. Nitrogen fixation was quantified by using (15)N isotope dilution method with two different cultivars grown in pot and field experiments. Higher nitrogen fixation was observed in variety Ponni than in ADT-43, where nearly 42% (field) and 40% (pot) of the nitrogen was derived from the atmosphere (% Ndfa). Isolate MGK3 was used to inoculate rice seedlings in a comparison with four other diazotrophs, viz., Gluconacetobacter diazotrophicus LMG7603, Herbaspirillum seropedicae LMG6513, Azospirillum lipoferum 4B LMG4348, and B. vietnamiensis LMG10929. They were used to conduct two pot and four field inoculation experiments. MGK3 alone, and combined with other diazotrophs, performed best under both pot and field conditions: combined inoculation produced yield increases between 9.5 and 23.6%, while MGK3 alone increased yield by 5.6 to 12.16% over the uninoculated control treatment.

  2. Single and mixed formulations of inoculants with diazotrophic bacteria, under different nitrogen rates and on the paddy rice crop

    Directory of Open Access Journals (Sweden)

    Paula Bianchet

    2013-12-01

    Full Text Available The use of diazotrophic bacteria as a biological input for the production of paddy rice can reduce nitrogen fertilizer applications and contribute to plant development. The use of mixed inoculants’ formulations can increase the efficiency of nitrogen fixation biological process. The objective of this study was to evaluate the effect of single and mixed formulations of inoculants with diazotrophic bacteria on the initial growth of paddy rice plants under different levels of N. The experiment was set in a greenhouse. Treatments consisted of four types of inoculation (no inoculation, inoculation with the isolated AI UDESC 27, inoculation with the isolated FE UDESC 22, and inoculation with the mixed formulation of isolated AI UDESC UDESC 27 and FE UDESC 22; and two levels of mineral nitrogen (30 and 60 mg kg-1 of N. The cultivar used was Epagri 109, which presents late maturity (over 140 days and high yield potential. Treatments were arranged in a factorial design (4 x 2 with five replicates. The experimental design was completely randomized. Inoculation with diazotrophic bacteria reduced by 18% and 26% shoot and root dry matter of rice plants, respectively. Plants also presented lower root area and volume when they were inoculated. There was no significant effect of inoculation and nitrogen rates on the number of leaves and tillers produced per plant or shoot nitrogen accumulation. The results showed that the isolated used in this work were not effective to stimulate shoot and root growth of cv Epagri 109, regardless of formulation type and rate of N.

  3. Dynamics of soil diazotrophic community structure, diversity, and functioning during the cropping period of cotton (Gossypium hirsutum).

    Science.gov (United States)

    Rai, Sandhya; Singh, Dileep Kumar; Annapurna, Kannepalli

    2015-01-01

    The soil sampled at different growth stages along the cropping period of cotton were analyzed using various molecular tools: restriction fragment length polymorphism (RFLP), terminal restriction length polymorphism (T-RFLP), and cloning-sequencing. The cluster analysis of the diazotrophic community structure of early sampled soil (0, 15, and 30 days) was found to be more closely related to each other than the later sampled one. Phylogenetic and diversity analysis of sequences obtained from the first (0 Day; C0) and last soil sample (180 day; C180) confirmed the data. The phylogenetic analysis revealed that C0 was having more unique sequences than C180 (presence of γ-Proteobacteria exclusively in C0). A relatively higher richness of diazotrophic community sequences was observed in C0 (S(ACE) : 30.76; S(Chao1) : 20.94) than C180 (S(ACE) : 18.00; S(Chao1) : 18.00) while the evenness component of Shannon diversity index increased from C0 (0.97) to C180 (1.15). The impact of routine agricultural activities was more evident based on diazotrophic activity (measured by acetylene reduction assay) than its structure and diversity. The nitrogenase activity of C0 (1264.85 ± 35.7 ηmol of ethylene production g(-1) dry soil h(-1) ) was statistically higher when compared to all other values (p structure/diversity and N2 fixation rates. Thus, considerable functional redundancy of nifH was concluded to be existing at the experimental site.

  4. Estimation of Nitrogenase Enzyme Activities and Plant Growth of Legume and Non-legume Inoculated with Diazotrophic Bacteria

    Directory of Open Access Journals (Sweden)

    Salwani S.

    2012-06-01

    Full Text Available Biological Nitrogen Fixation (BNF process benefits the agriculture sector especially for reducing cost of nitrogenfertilizer. In the process, the diazotrophs convert N2 into ammonia (NH3 which is useable by plants. The BNF process iscatalysed by nitrogenase enzyme that involved protons and electrons together with evolution of H2 therefore, theassessment of N2 fixation is also available via H2 production and electron allocation analysis. Thus, the aims of thisexperiment were to estimate the nitrogenase enzyme activities and observe the influence of diazothrophs on growth oflegume (soybean and non legume (rice plants. Host plants were inoculated with respective inocula; Bradyrhizobiumjaponicum (strain 532C for soybean while Azospirillum brasilense (Sp7 and locally isolated diazotroph (isolate 5 forrice. At harvest, the plants were observed for plant growth parameters, H2 evolution, N2 fixation and electron allocationcoefficient (EAC values. The experiment recorded N2 fixation activities of inoculated soybean plants at 141.2 μmol N2 h-1g-1 dry weight nodule, and the evolution of H2 at 144.4 μmol H2 h-1 g-1 dry weight nodule. The electron allocationcoefficient (EAC of soybean was recorded at 0.982. For inoculated rice plants, none of the observations was successfully recorded. However, results for chlorophyll contents and plant dry weight of both plants inoculated with respective inocula were similar to the control treatments supplied with full nitrogen fertilization (+N. The experiment clearly showed that inoculation of diazotrophic bacteria could enhance growth of the host plants similar to plants treated with nitrogenous fertilizer due to efficient N2 fixation process

  5. Distribution and drivers of symbiotic and free-living diazotrophic cyanobacteria in the Western Tropical South Pacific

    OpenAIRE

    Stenegren, Marcus; Caputo, Andrea; Berg, Carlo; Bonnet, Sophie; Foster, Rachel A.

    2017-01-01

    The abundance and distribution of cyanobacterial diazotrophs were quantified in two regions (Melanesian archipelago, MA and subtropical gyre, SG) of the Western Tropical South Pacific using nifH qPCR assays. UCYN-A1 and A2 host populations were quantified using 18S rRNA qPCR assays including one newly developed assay. All phylotypes were detected in the upper photic zone (0–50 m), with higher abundances in the MA region. Trichodesmium and UCYN-B dominated, composing 81–100&...

  6. DRIVERS OF THE DYNAMICS OF DIAZOTROPHS AND DENITRIFIERS IN NORTH SEA BOTTOM WATERS AND SEDIMENTS

    Directory of Open Access Journals (Sweden)

    Lucas eStal

    2015-07-01

    Full Text Available The fixation of dinitrogen (N2 and denitrification are two opposite processes in the nitrogen cycle. The former transfers atmospheric dinitrogen gas into bound nitrogen in the biosphere, while the latter returns this bound nitrogen back to atmospheric dinitrogen. It is unclear whether or not these processes are intimately connected in any microbial ecosystem or that they are spatially and/or temporally separated. Here, we measured seafloor nitrogen fixation and denitrification as well as pelagic nitrogen fixation by using the stable isotope technique. Alongside, we measured the diversity, abundance, and activity of nitrogen-fixing and denitrifying microorganisms at three stations in the southern North Sea. Nitrogen fixation ranged from undetectable to 2.4 nmol N L-1 d-1 and from undetectable to 8.2 nmol N g-1 d-1 in the water column and seafloor, respectively. The highest rates were measured in August at Doggersbank, both for the water column and for the seafloor. Denitrification ranged from 1.7 to 208.8 µmol m-2 d-1 and the highest rates were measured in May at the Oyster Grounds. DNA sequence analysis showed sequences of nifH, a structural gene for nitrogenase, related to sequences from anaerobic sulfur/iron reducers and sulfate reducers. Sequences of the structural gene for nitrite reductase, nirS, were related to environmental clones from marine sediments. Quantitative polymerase chain reaction (qPCR data revealed the highest abundance of nifH and nirS genes at the Oyster Grounds. Quantitative reverse transcription polymerase chain reaction (qRT-PCR data revealed the highest nifH expression at Doggersbank and the highest nirS expression at the Oyster Grounds. The distribution of the diazotrophic and denitrifying communities seems to be subject to different selecting factors, leading to spatial and temporal separation of nitrogen fixation and denitrification. These selecting factors include temperature, organic matter availability, and

  7. Metabolic engineering of a diazotrophic bacterium improves ammonium release and biofertilization of plants and microalgae.

    Science.gov (United States)

    Ambrosio, Rafael; Ortiz-Marquez, Juan Cesar Federico; Curatti, Leonardo

    2017-03-01

    The biological nitrogen fixation carried out by some Bacteria and Archaea is one of the most attractive alternatives to synthetic nitrogen fertilizers. However, with the exception of the symbiotic rhizobia-legumes system, progress towards a more extensive realization of this goal has been slow. In this study we manipulated the endogenous regulation of both nitrogen fixation and assimilation in the aerobic bacterium Azotobacter vinelandii. Substituting an exogenously inducible promoter for the native promoter of glutamine synthetase produced conditional lethal mutant strains unable to grow diazotrophically in the absence of the inducer. This mutant phenotype could be reverted in a double mutant strain bearing a deletion in the nifL gene that resulted in constitutive expression of nif genes and increased production of ammonium. Under GS non-inducing conditions both the single and the double mutant strains consistently released very high levels of ammonium (>20mM) into the growth medium. The double mutant strain grew and excreted high levels of ammonium under a wider range of concentrations of the inducer than the single mutant strain. Induced mutant cells could be loaded with glutamine synthetase at different levels, which resulted in different patterns of extracellular ammonium accumulation afterwards. Inoculation of the engineered bacteria into a microalgal culture in the absence of sources of C and N other than N2 and CO2 from the air, resulted in a strong proliferation of microalgae that was suppressed upon addition of the inducer. Both single and double mutant strains also promoted growth of cucumber plants in the absence of added N-fertilizer, while this property was only marginal in the parental strain. This study provides a simple synthetic genetic circuit that might inspire engineering of optimized inoculants that efficiently channel N2 from the air into crops. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All

  8. Refolding and enzyme kinetic studies on the ferrochelatase of the cyanobacterium Synechocystis sp. PCC 6803.

    Directory of Open Access Journals (Sweden)

    Patrik Storm

    Full Text Available Heme is a cofactor for proteins participating in many important cellular processes, including respiration, oxygen metabolism and oxygen binding. The key enzyme in the heme biosynthesis pathway is ferrochelatase (protohaem ferrolyase, EC 4.99.1.1, which catalyzes the insertion of ferrous iron into protoporphyrin IX. In higher plants, the ferrochelatase enzyme is localized not only in mitochondria, but also in chloroplasts. The plastidic type II ferrochelatase contains a C-terminal chlorophyll a/b (CAB motif, a conserved hydrophobic stretch homologous to the CAB domain of plant light harvesting proteins and light-harvesting like proteins. This type II ferrochelatase, found in all photosynthetic organisms, is presumed to have evolved from the cyanobacterial ferrochelatase. Here we describe a detailed enzymological study on recombinant, refolded and functionally active type II ferrochelatase (FeCh from the cyanobacterium Synechocystis sp. PCC 6803. A protocol was developed for the functional refolding and purification of the recombinant enzyme from inclusion bodies, without truncation products or soluble aggregates. The refolded FeCh is active in its monomeric form, however, addition of an N-terminal His(6-tag has significant effects on its enzyme kinetics. Strikingly, removal of the C-terminal CAB-domain led to a greatly increased turnover number, k(cat, compared to the full length protein. While pigments isolated from photosynthetic membranes decrease the activity of FeCh, direct pigment binding to the CAB domain of FeCh was not evident.

  9. Refolding and enzyme kinetic studies on the ferrochelatase of the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Storm, Patrik; Tibiletti, Tania; Hall, Michael; Funk, Christiane

    2013-01-01

    Heme is a cofactor for proteins participating in many important cellular processes, including respiration, oxygen metabolism and oxygen binding. The key enzyme in the heme biosynthesis pathway is ferrochelatase (protohaem ferrolyase, EC 4.99.1.1), which catalyzes the insertion of ferrous iron into protoporphyrin IX. In higher plants, the ferrochelatase enzyme is localized not only in mitochondria, but also in chloroplasts. The plastidic type II ferrochelatase contains a C-terminal chlorophyll a/b (CAB) motif, a conserved hydrophobic stretch homologous to the CAB domain of plant light harvesting proteins and light-harvesting like proteins. This type II ferrochelatase, found in all photosynthetic organisms, is presumed to have evolved from the cyanobacterial ferrochelatase. Here we describe a detailed enzymological study on recombinant, refolded and functionally active type II ferrochelatase (FeCh) from the cyanobacterium Synechocystis sp. PCC 6803. A protocol was developed for the functional refolding and purification of the recombinant enzyme from inclusion bodies, without truncation products or soluble aggregates. The refolded FeCh is active in its monomeric form, however, addition of an N-terminal His(6)-tag has significant effects on its enzyme kinetics. Strikingly, removal of the C-terminal CAB-domain led to a greatly increased turnover number, k(cat), compared to the full length protein. While pigments isolated from photosynthetic membranes decrease the activity of FeCh, direct pigment binding to the CAB domain of FeCh was not evident.

  10. Modeling culture profiles of the heterocystous N2-fixing cyanobacterium Anabaena flos-aquae.

    Science.gov (United States)

    Pinzon, Neissa M; Ju, Lu-Kwang

    2006-01-01

    Heterocyst differentiation is a unique feature of nitrogen-fixing cyanobacteria, potentially important for photobiological hydrogen production. Despite the significant advances in genetic investigation on heterocyst differentiation, there were no quantitative culture-level models that describe the effects of cellular activities and cultivation conditions on the heterocyst differentiation. Such a model was developed in this study, incorporating photosynthetic growth of vegetative cells, heterocyst differentiation, self-shading effect on light penetration, and nitrogen fixation. The model parameters were determined by fitting experimental results from the growth of the heterocystous cyanobacterium Anabaena flos-aquae CCAP 1403/13f in media without and with different nitrate concentrations and under continuous illumination of white light at different light intensities (2, 5, 10, 17, 20 and 50 microE m-2 s-1). The model describes the experimental profiles well and gives reasonable predictions even for the transition of growth from that on external N source to that via nitrogen fixation, responding to the change in external N concentrations. The significance and implications of the best-fit values of the model parameters are discussed.

  11. Refolding and Enzyme Kinetic Studies on the Ferrochelatase of the Cyanobacterium Synechocystis sp. PCC 6803

    Science.gov (United States)

    Storm, Patrik; Tibiletti, Tania; Hall, Michael; Funk, Christiane

    2013-01-01

    Heme is a cofactor for proteins participating in many important cellular processes, including respiration, oxygen metabolism and oxygen binding. The key enzyme in the heme biosynthesis pathway is ferrochelatase (protohaem ferrolyase, EC 4.99.1.1), which catalyzes the insertion of ferrous iron into protoporphyrin IX. In higher plants, the ferrochelatase enzyme is localized not only in mitochondria, but also in chloroplasts. The plastidic type II ferrochelatase contains a C-terminal chlorophyll a/b (CAB) motif, a conserved hydrophobic stretch homologous to the CAB domain of plant light harvesting proteins and light-harvesting like proteins. This type II ferrochelatase, found in all photosynthetic organisms, is presumed to have evolved from the cyanobacterial ferrochelatase. Here we describe a detailed enzymological study on recombinant, refolded and functionally active type II ferrochelatase (FeCh) from the cyanobacterium Synechocystis sp. PCC 6803. A protocol was developed for the functional refolding and purification of the recombinant enzyme from inclusion bodies, without truncation products or soluble aggregates. The refolded FeCh is active in its monomeric form, however, addition of an N-terminal His6-tag has significant effects on its enzyme kinetics. Strikingly, removal of the C-terminal CAB-domain led to a greatly increased turnover number, kcat, compared to the full length protein. While pigments isolated from photosynthetic membranes decrease the activity of FeCh, direct pigment binding to the CAB domain of FeCh was not evident. PMID:23390541

  12. The Psb32 Protein Aids in Repairing Photodamaged Photosystem Ⅱ in the Cyanobacterium Synechocystis 6803

    Institute of Scientific and Technical Information of China (English)

    Kimberly M. Wegener; Stefan Bennewitz; Ralf Oelmüller; Himadri B. Pakrasi

    2011-01-01

    Photosystem Ⅱ (PSⅡ),a membrane protein complex,catalyzes the photochemical oxidation of water to molecular oxygen.This enzyme complex consists of approximately 20 stoichiometric protein components.However,due to the highly energetic reactions it catalyzes as part of its normal activity,PSⅡ is continuously damaged and repaired.With advances in protein detection technologies,an increasing number of sub-stoichiometric PSⅡ proteins have been identified,many of which aid in the biogenesis and assembly of this protein complex.Psb32 (SⅡ1390) has previously been identified as a protein associated with highly active purified PSⅡ preparations from the cyanobacterium Synechocystis sp.PCC 6803.To investigate its function,the subcellular localization of Psb32 and the impact of deletion of the psb32 gene on PSⅡ were analyzed.Here,we show that Psb32 is an integral membrane protein,primarily located in the thylakoid membranes.Although not required for cell viability,Psb32 protects cells from oxidative stress and additionally confers a selective fitness advantage in mixed culture experiments.Specifically,Psb32 protects PSⅡ from photodamage and accelerates its repair.Thus,the data suggest that Psb32 plays an important role in minimizing the effect of photoinhibition on PSⅡ.

  13. The primary transcriptome of the marine diazotroph Trichodesmium erythraeum IMS101

    Science.gov (United States)

    Pfreundt, Ulrike; Kopf, Matthias; Belkin, Natalia; Berman-Frank, Ilana; Hess, Wolfgang R.

    2014-08-01

    Blooms of the dinitrogen-fixing marine cyanobacterium Trichodesmium considerably contribute to new nitrogen inputs into tropical oceans. Intriguingly, only 60% of the Trichodesmium erythraeum IMS101 genome sequence codes for protein, compared with ~85% in other sequenced cyanobacterial genomes. The extensive non-coding genome fraction suggests space for an unusually high number of unidentified, potentially regulatory non-protein-coding RNAs (ncRNAs). To identify the transcribed fraction of the genome, here we present a genome-wide map of transcriptional start sites (TSS) at single nucleotide resolution, revealing the activity of 6,080 promoters. We demonstrate that T. erythraeum has the highest number of actively splicing group II introns and the highest percentage of TSS yielding ncRNAs of any bacterium examined to date. We identified a highly transcribed retroelement that serves as template repeat for the targeted mutation of at least 12 different genes by mutagenic homing. Our findings explain the non-coding portion of the T. erythraeum genome by the transcription of an unusually high number of non-coding transcripts in addition to the known high incidence of transposable elements. We conclude that riboregulation and RNA maturation-dependent processes constitute a major part of the Trichodesmium regulatory apparatus.

  14. Use of endophytic diazotrophic bacteria as a vector to express the cry3A gene from Bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    Salles Joana Falcão

    2000-01-01

    Full Text Available The goal of this study was to evaluate the potential of endophytic diazotrophic bacteria as a vector to express a cry gene from Bacillus thuringiensis, envisaging the control of pests that attack sugarcane plants. The endophytic nitrogen-fixing bacteria Gluconacetobacter diazotrophicus strain BR11281 and Herbaspirillum seropedicae strain BR11335 were used as models. The cry3A gene was transferred by conjugation using a suicide plasmid and the recombinant strains were selected by their ability to fix nitrogen in semi-solid N-free medium. The presence of the cry gene was detected by Southern-blot using an internal fragment of 1.0 kb as a probe. The production of delta-endotoxin by the recombinant H. seropedicae strain was detected by dot blot while for G. diazotrophicus the Western-blot technique was used. In both cases, a specific antibody raised against the B. thuringiensis toxin was applied. The delta-endotoxin production showed by the G. diazotrophicus recombinant strain was dependent on the nitrogen fixing conditions since the cry3A gene was fused to a nif promoter. In the case of H. seropedicae the delta-endotoxin expression was not affected by the promoter (rhi used. These results suggest that endophytic diazotrophic bacteria can be used as vectors to express entomopathogenic genes envisaging control of sugarcane pests.

  15. Sucrose secreted by the engineered cyanobacterium and its fermentability

    Science.gov (United States)

    Duan, Yangkai; Luo, Quan; Liang, Feiyan; Lu, Xuefeng

    2016-10-01

    The unicellular cyanobacterium, Synechococcus elongatus PCC 7942 (Syn7942), synthesizes sucrose as the only compatible solute under salt stress. A series of engineered Syn7942 strains for sucrose production were constructed. The overexpression of the native sps (encoding a natively fused protein of sucrose phosphate synthase SPS and sucrose phosphate phosphatase SPP) in Syn7942 wild type caused a 93% improvement of sucrose productivity. The strain FL130 co-overexpressing sps and cscB (encoding a sucrose transporter) exhibited a 74% higher extracellular sucrose production than that overexpressing cscB only. Both results showed the significant improvement of sucrose productivity by the double functional protein SPS-SPP. Afterwards, FL130 was cultivated under a modified condition, and the cell-free culture medium containing 1.5 g L-1 sucrose was pre-treated with an acid hydrolysis technique. Cultivated with the neutralized hydrolysates as the starting media, two widely used microorganisms, Escherichia coli and Saccharomyces cerevisiae, showed a comparable growth with that in the control media supplemented with glucose. These results clearly demonstrated that the cell-free culture of sucrose-secreting cyanobacteria can be applied as starting media in microbial cultivation.

  16. Ribulose diphosphate carboxylase of the cyanobacterium Spirulina platensis

    Energy Technology Data Exchange (ETDEWEB)

    Terekhova, I.V.; Chernyad' ev, I.I.; Doman, N.G.

    1986-11-20

    The ribulose diphosphate (RDP) carboxylase activity of the cyanobacterium Spirulina platensis is represented by two peaks when a cell homogenate is centrifuged in a sucrose density gradient. In the case of differential centrifugation (40,000 g, 1 h), the activity of the enzyme was distributed between the supernatant liquid (soluble form) and the precipitate (carboxysomal form). From the soluble fraction, in which 80-95% of the total activity of the enzyme is concentrated, electrophoretically homogeneous RDP carboxylase was isolated by precipitation with ammonium sulfate and centrifugation in a sucrose density gradient. The purified enzyme possessed greater electrophoretic mobility in comparison with the RDP carboxylase of beans Vicia faba. The molecular weight of the enzyme, determined by gel filtration, was 450,000. The enzyme consists of monotypic subunits with a molecular weight of 53,000. The small subunits were not detected in electrophoresis in polyacrylamide gel in the presence of SDS after fixation and staining of the gels by various methods.

  17. ADAPTIVE RESPONSES OF CYANOBACTERIUM PLECTONEMA BORYANUM TO HERBICIDE BUTACHLOR

    Directory of Open Access Journals (Sweden)

    Rishav Kumar

    2012-08-01

    Full Text Available The Present paper deals with the herbicide Butachlor (5,10 ,20,40 and 80ppm-induced changes in physiological and biochemical parameters related to photosynthesis and defense systems in paddy field cyanobacterium Plectonema boryanum grown under laboratory conditions. Growth and photosynthetic pigments, i.e., chlorophyll a and carotenoids were adversely affected by Butachlor treatment and the inhibition was found to be dose dependent. The toxic effect of Butachlor was more pronounced protein; however, a considerable reduction in chlorophyll a, and carotenoids was also noticed. Furthermore, Butachlor with increasing doses accelerated the formation of active oxygen species, i.e., O2- and H2O2, in cells progressively. As a consequence of active oxygen species (AOS generation in Butachlor -treated cells, the activity of superoxide dismutase (SOD and peroxidase (POD was enhanced considerably. Besides the accelerated action of enzymatic defense systems, Protein damage also showed an increasing trend with the rising concentration of Butachlor (5, 10, 20, 40 and 80 ppm.

  18. Fractionation and identification of metalloproteins from a marine cyanobacterium.

    Science.gov (United States)

    Barnett, James P; Scanlan, David J; Blindauer, Claudia A

    2012-04-01

    Trace metals are essential for the growth of marine cyanobacteria, being required for key cellular processes such as photosynthesis and respiration. Despite this, the metalloproteomes of marine cyanobacteria are at present only poorly defined. In this study, we have probed the major cobalt, iron, manganese, and nickel-binding proteins in the marine cyanobacterium Synechococcus sp. WH8102 by using two different fractionation approaches combined with peptide mass fingerprinting. For the identification of intact metalloproteins, multidimensional native chromatography was used to fractionate the proteome, followed by inorganic mass spectrometry to identify metal-enriched fractions. This approach led to the detection of nickel superoxide dismutase together with its predicted cofactor. We also explored the utility of immobilized metal affinity chromatography (IMAC) to isolate subpopulations of proteins that display affinity for a particular metal ion. We conclude that low-resolution 2D liquid chromatography is a viable fractionation technique to correlate relatively low-abundance metal ions with their few cellular destinations (e.g. Ni), but challenges remain for more abundant metals with multiple destinations such as iron. IMAC has been shown as a useful pre-fractionation technique to screen for proteins with metal-binding capacity, and may become a particularly valuable tool for the identification of metal-trafficking proteins.

  19. Export of Extracellular Polysaccharides Modulates Adherence of the Cyanobacterium Synechocystis

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, ML; Allen, R; Luo, YQ; Curtiss, R

    2013-09-10

    The field of cyanobacterial biofuel production is advancing rapidly, yet we know little of the basic biology of these organisms outside of their photosynthetic pathways. We aimed to gain a greater understanding of how the cyanobacterium Synechocystis PCC 6803 (Synechocystis, hereafter) modulates its cell surface. Such understanding will allow for the creation of mutants that autoflocculate in a regulated way, thus avoiding energy intensive centrifugation in the creation of biofuels. We constructed mutant strains lacking genes predicted to function in carbohydrate transport or synthesis. Strains with gene deletions of slr0977 (predicted to encode a permease component of an ABC transporter), slr0982 (predicted to encode an ATP binding component of an ABC transporter) and slr1610 (predicted to encode a methyltransferase) demonstrated flocculent phenotypes and increased adherence to glass. Upon bioinformatic inspection, the gene products of slr0977, slr0982, and slr1610 appear to function in O-antigen (OAg) transport and synthesis. However, the analysis provided here demonstrated no differences between OAg purified from wild-type and mutants. However, exopolysaccharides (EPS) purified from mutants were altered in composition when compared to wild-type. Our data suggest that there are multiple means to modulate the cell surface of Synechocystis by disrupting different combinations of ABC transporters and/or glycosyl transferases. Further understanding of these mechanisms may allow for the development of industrially and ecologically useful strains of cyanobacteria. Additionally, these data imply that many cyanobacterial gene products may possess as-yet undiscovered functions, and are meritorious of further study.

  20. Construction of a cyanobacterium synthesizing cyclopropane fatty acids.

    Science.gov (United States)

    Machida, Shuntaro; Shiraiwa, Yoshihiro; Suzuki, Iwane

    2016-09-01

    Microalgae have received much attention as a next-generation source of biomass energy. However, most of the fatty acids (FAs) from microalgae are multiply unsaturated; thus, the biofuels derived from them are fluid, but vulnerable to oxidation. In this study, we attempted to synthesize cyclopropane FAs in the cyanobacterium Synechocystis sp. PCC 6803 by expressing the cfa gene for cyclopropane FA synthase from Escherichia coli with the aim of producing FAs that are fluid and stable in response to oxidization. We successfully synthesized cyclopropane FAs in Synechocystis with a yield of ~30% of total FAs. Growth of the transformants was altered, particularly at low temperatures, but photosynthesis and respiration were not significantly affected. C16:1(∆9) synthesis in the desA(-)/desD(-) strain by expression of the desC2 gene for sn-2 specific ∆9 desaturase positively affected growth at low temperatures via promotion of various cellular processes, with the exceptions of photosynthesis and respiration. Estimation of the apparent activities of desaturases suggested that some acyl-lipid desaturases might recognize the lipid side chain.

  1. Photosynthetic Versatility in the Genome of Geitlerinema sp. PCC 9228 (Formerly Oscillatoria limnetica ‘Solar Lake’), a Model Anoxygenic Photosynthetic Cyanobacterium

    Science.gov (United States)

    Grim, Sharon L.; Dick, Gregory J.

    2016-01-01

    Anoxygenic cyanobacteria that use sulfide as the electron donor for photosynthesis are a potentially influential but poorly constrained force on Earth’s biogeochemistry. Their versatile metabolism may have boosted primary production and nitrogen cycling in euxinic coastal margins in the Proterozoic. In addition, they represent a biological mechanism for limiting the accumulation of atmospheric oxygen, especially before the Great Oxidation Event and in the low-oxygen conditions of the Proterozoic. In this study, we describe the draft genome sequence of Geitlerinema sp. PCC 9228, formerly Oscillatoria limnetica ‘Solar Lake’, a mat-forming diazotrophic cyanobacterium that can switch between oxygenic photosynthesis and sulfide-based anoxygenic photosynthesis (AP). Geitlerinema possesses three variants of psbA, which encodes protein D1, a core component of the photosystem II reaction center. Phylogenetic analyses indicate that one variant is closely affiliated with cyanobacterial psbA genes that code for a D1 protein used for oxygen-sensitive processes. Another version is phylogenetically similar to cyanobacterial psbA genes that encode D1 proteins used under microaerobic conditions, and the third variant may be cued to high light and/or elevated oxygen concentrations. Geitlerinema has the canonical gene for sulfide quinone reductase (SQR) used in cyanobacterial AP and a putative transcriptional regulatory gene in the same operon. Another operon with a second, distinct sqr and regulatory gene is present, and is phylogenetically related to sqr genes used for high sulfide concentrations. The genome has a comprehensive nif gene suite for nitrogen fixation, supporting previous observations of nitrogenase activity. Geitlerinema possesses a bidirectional hydrogenase rather than the uptake hydrogenase typically used by cyanobacteria in diazotrophy. Overall, the genome sequence of Geitlerinema sp. PCC 9228 highlights potential cyanobacterial strategies to cope with

  2. Photosynthetic versatility in the genome of Geitlerinema sp. PCC 9228 (formerly Oscillatoria limnetica ‘Solar Lake’, a model anoxygenic photosynthetic cyanobacterium

    Directory of Open Access Journals (Sweden)

    Sharon L Grim

    2016-10-01

    Full Text Available Anoxygenic cyanobacteria that use sulfide as the electron donor for photosynthesis are a potentially influential but poorly constrained force on Earth’s biogeochemistry. Their versatile metabolism may have boosted primary production and nitrogen cycling in euxinic coastal margins in the Proterozoic. In addition, they represent a biological mechanism for limiting the accumulation of atmospheric oxygen, especially before the Great Oxidation Event and in the low-oxygen conditions of the Proterozoic. In this study, we describe the draft genome sequence of Geitlerinema sp. PCC 9228, formerly Oscillatoria limnetica ‘Solar Lake’, a mat-forming diazotrophic cyanobacterium that can switch between oxygenic photosynthesis and sulfide-based anoxygenic photosynthesis. Geitlerinema possesses three variants of psbA, which encodes protein D1, a core component of the photosystem II reaction center. Phylogenetic analyses indicate that one variant is closely affiliated with cyanobacterial psbA genes that code for a D1 protein used for oxygen-sensitive processes. Another version is phylogenetically similar to cyanobacterial psbA genes that encode D1 proteins used under microaerobic conditions, and the third variant may be cued to high light and/or elevated oxygen concentrations. Geitlerinema has the canonical gene for sulfide quinone reductase (SQR used in cyanobacterial anoxygenic photosynthesis and a putative transcriptional regulatory gene in the same operon. Another operon with a second, distinct sqr and regulatory gene is present, and is phylogenetically related to sqr genes used for high sulfide concentrations. The genome has a comprehensive nif gene suite for nitrogen fixation, supporting previous observations of nitrogenase activity. Geitlerinema possesses a bidirectional hydrogenase rather than the uptake hydrogenase typically used by cyanobacteria in diazotrophy. Overall, the genome sequence of Geitlerinema sp. PCC 9228 highlights potential

  3. Visualizing Single Cell Biology: Nanosims Studies of Carbon and Nitrogen Metabolism in Diazotrophic Cyanobacteria

    Science.gov (United States)

    Pett-Ridge, J.; Finzi, J. A.; Capone, D. G.; Popa, R.; Nealson, K. H.; Ng, W.; Spormann, A. M.; Hutcheon, I. D.; Weber, P. K.

    2007-12-01

    Filamentous nitrogen fixing (diazotrophic) cyanobacteria are key players in global nutrient cycling, but the relationship between CO2- and N2-fixation and intercellular exchange of these elements remains poorly understood in many genera. These bacteria are faced with the challenge of isolating regions of N-fixation (O2 inhibited) and photosynthetic (O2 producing) activity. We used isotope labeling in conjunction with a high-resolution isotope and elemental mapping technique (NanoSIMS) to quantitatively describe 13C and 15N uptake and transport in two aquatic cyanobacteria grown on NaH13CO3 and 15N2. The technical challenges of tracing isotopes within individual bacteria can be overcome with high resolution Secondary Ion Mass Spectrometry (NanoSIMS). In NanoSIMS analysis, samples are sputtered with an energetic primary beam (Cs+, O-) liberating secondary ions that are separated by the mass spectrometer and detected in a suite of electron multipliers. Five isotopic species may be analyzed concurrently with spatial resolution as fine as 50nm. A high sensitivity isotope ratio 'map' can then be generated for the analyzed area. Using sequentially harvested cyanobacteria in conjunction with enriched H13CO3 and 15N2 incubations, we measured temporal enrichment patterns that evolve over the course of a day's growth and suggest tightly regulated changes in fixation kinetics. With a combination of TEM, SEM and NanoSIMS analyses, we also mapped the distribution of C, N and Mo (a critical nitrogenase co-factor) isotopes in intact cells. Our results suggest that NanoSIMS mapping of metal enzyme co-factors may be a powerful method of identifying physiological and morphological characteristics within individual bacterial cells, and could be used to provide a 3-dimensional context for more traditional analyses such as immunogold labeling. Finally, we resolved patterns of isotope enrichment at multiple spatial scales: sub-cellular variation, cell-cell differences along filaments

  4. The nitrogen-fixation island insertion site is conserved in diazotrophic Pseudomonas stutzeri and Pseudomonas sp. isolated from distal and close geographical regions.

    Directory of Open Access Journals (Sweden)

    Anastasia Venieraki

    Full Text Available The presence of nitrogen fixers within the genus Pseudomonas has been established and so far most isolated strains are phylogenetically affiliated to Pseudomonas stutzeri. A gene ortholog neighborhood analysis of the nitrogen fixation island (NFI in four diazotrophic P. stutzeri strains and Pseudomonas azotifigens revealed that all are flanked by genes coding for cobalamin synthase (cobS and glutathione peroxidise (gshP. The putative NFIs lack all the features characterizing a mobilizable genomic island. Nevertheless, bioinformatic analysis P. stutzeri DSM 4166 NFI demonstrated the presence of short inverted and/or direct repeats within both flanking regions. The other P. stutzeri strains carry only one set of repeats. The genetic diversity of eleven diazotrophic Pseudomonas isolates was also investigated. Multilocus sequence typing grouped nine isolates along with P. stutzeri and two isolates are grouped in a separate clade. A Rep-PCR fingerprinting analysis grouped the eleven isolates into four distinct genotypes. We also provided evidence that the putative NFI in our diazotrophic Pseudomonas isolates is flanked by cobS and gshP genes. Furthermore, we demonstrated that the putative NFI of Pseudomonas sp. Gr65 is flanked by inverted repeats identical to those found in P. stutzeri DSM 4166 and while the other P. stutzeri isolates harbor the repeats located in the intergenic region between cobS and glutaredoxin genes as in the case of P. stutzeri A1501. Taken together these data suggest that all putative NFIs of diazotrophic Pseudomonas isolates are anchored in an intergenic region between cobS and gshP genes and their flanking regions are designated by distinct repeats patterns. Moreover, the presence of almost identical NFIs in diazotrophic Pseudomonas strains isolated from distal geographical locations around the world suggested that this horizontal gene transfer event may have taken place early in the evolution.

  5. Abundance and distribution of major groups of diazotrophic cyanobacteria and their potential contribution to N₂ fixation in the tropical Atlantic Ocean.

    Science.gov (United States)

    Goebel, Nicole L; Turk, Kendra A; Achilles, Katherine M; Paerl, Ryan; Hewson, Ian; Morrison, Amanda E; Montoya, Joseph P; Edwards, Christopher A; Zehr, Jonathan P

    2010-12-01

    The abundances of six N₂-fixing cyanobacterial phylotypes were profiled at 22 stations across the tropical Atlantic Ocean during June 2006, and used to model the contribution of the diazotrophs to N₂ fixation. Diazotroph abundances were measured by targeting the nifH gene of Trichodesmium, unicellular groups A, B, C (UCYN-A, UCYN-B and UCYN-C), and diatom-cyanobiont symbioses Hemiaulus-Richelia, Rhizosolenia-Richelia and Chaetoceros-Calothrix. West to east gradients in temperature, salinity and nutrients [NO₃⁻ + NO₂⁻, PO₄³⁻, Si(OH)₄] showed the influence of the Amazon River plume and its effect on the distributions of the diazotrophs. Trichodesmium accounted for more than 93% of all nifH genes detected, dominated the warmer waters of the western Atlantic, and was the only diazotroph detected at the equatorial upwelling station. UCYN-A was the next most abundant (> 5% of all nifH genes) and dominated the cooler waters of the eastern Atlantic near the Cape Verde Islands. UCYN-C was found at a single depth (200 m) of high salinity and low temperature and nutrients, whereas UCYN-B cells were widespread but in very low abundance (6.1 × 10¹ ± 4.6 × 10² gene copies l⁻¹). The diatom-cyanobionts were observed primarily in the western Atlantic within or near the high Si(OH)₄ input of the Amazon River plume. Overall, highest diazotroph abundances were observed at the surface and declined with depth, except for some subsurface peaks in Trichodesmium, UCYN-B and UCYN-A. Modelled contributions of Trichodesmium, UCYN-B and UCYN-A to total N₂ fixation suggested that Trichodesmium had the largest input, except for the potential of UCYN-A at the Cape Verde Islands.

  6. The nitrogen-fixation island insertion site is conserved in diazotrophic Pseudomonas stutzeri and Pseudomonas sp. isolated from distal and close geographical regions.

    Science.gov (United States)

    Venieraki, Anastasia; Dimou, Maria; Vezyri, Eleni; Vamvakas, Alexandros; Katinaki, Pagona-Artemis; Chatzipavlidis, Iordanis; Tampakaki, Anastasia; Katinakis, Panagiotis

    2014-01-01

    The presence of nitrogen fixers within the genus Pseudomonas has been established and so far most isolated strains are phylogenetically affiliated to Pseudomonas stutzeri. A gene ortholog neighborhood analysis of the nitrogen fixation island (NFI) in four diazotrophic P. stutzeri strains and Pseudomonas azotifigens revealed that all are flanked by genes coding for cobalamin synthase (cobS) and glutathione peroxidise (gshP). The putative NFIs lack all the features characterizing a mobilizable genomic island. Nevertheless, bioinformatic analysis P. stutzeri DSM 4166 NFI demonstrated the presence of short inverted and/or direct repeats within both flanking regions. The other P. stutzeri strains carry only one set of repeats. The genetic diversity of eleven diazotrophic Pseudomonas isolates was also investigated. Multilocus sequence typing grouped nine isolates along with P. stutzeri and two isolates are grouped in a separate clade. A Rep-PCR fingerprinting analysis grouped the eleven isolates into four distinct genotypes. We also provided evidence that the putative NFI in our diazotrophic Pseudomonas isolates is flanked by cobS and gshP genes. Furthermore, we demonstrated that the putative NFI of Pseudomonas sp. Gr65 is flanked by inverted repeats identical to those found in P. stutzeri DSM 4166 and while the other P. stutzeri isolates harbor the repeats located in the intergenic region between cobS and glutaredoxin genes as in the case of P. stutzeri A1501. Taken together these data suggest that all putative NFIs of diazotrophic Pseudomonas isolates are anchored in an intergenic region between cobS and gshP genes and their flanking regions are designated by distinct repeats patterns. Moreover, the presence of almost identical NFIs in diazotrophic Pseudomonas strains isolated from distal geographical locations around the world suggested that this horizontal gene transfer event may have taken place early in the evolution.

  7. Arsenic biotransformation by a cyanobacterium Nostoc sp. PCC 7120.

    Science.gov (United States)

    Xue, Xi-Mei; Yan, Yu; Xiong, Chan; Raber, Georg; Francesconi, Kevin; Pan, Ting; Ye, Jun; Zhu, Yong-Guan

    2017-09-01

    Nostoc sp. PCC 7120 (Nostoc), a typical filamentous cyanobacterium ubiquitous in aquatic system, is recognized as a model organism to study prokaryotic cell differentiation and nitrogen fixation. In this study, Nostoc cells incubated with arsenite (As(III)) for two weeks were extracted with dichloromethane/methanol (DCM/MeOH) and the extract was partitioned between water and DCM. Arsenic species in aqueous and DCM layers were determined using high performance liquid chromatography - inductively coupled plasma mass spectrometer/electrospray tandem mass spectrometry (HPLC-ICPMS/ESIMSMS). In addition to inorganic arsenic (iAs), the aqueous layer also contained monomethylarsonate (MAs(V)), dimethylarsinate (DMAs(V)), and the two arsenosugars, namely a glycerol arsenosugar (Oxo-Gly) and a phosphate arsenosugar (Oxo-PO4). Two major arsenosugar phospholipids (AsSugPL982 and AsSugPL984) were detected in DCM fraction. Arsenic in the growth medium was also investigated by HPLC/ICPMS and shown to be present mainly as the inorganic forms As(III) and As(V) accounting for 29%-38% and 29%-57% of the total arsenic respectively. The total arsenic of methylated arsenic, arsenosugars, and arsenosugar phospholipids in Nostoc cells with increasing As(III) exposure were not markedly different, indicating that the transformation to organoarsenic in Nostoc was not dependent on As(III) concentration in the medium. Our results provide new insights into the role of cyanobacteria in the biogeochemical cycling of arsenic. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Ferredoxin and flavodoxin from the cyanobacterium Synechocystis sp PCC 6803.

    Science.gov (United States)

    Bottin, H; Lagoutte, B

    1992-07-06

    The unicellular cyanobacterium Synechocystis sp PCC 6803 is capable of synthesizing two different Photosystem-I electron acceptors, ferredoxin and flavodoxin. Under normal growth conditions a [2Fe-2S] ferredoxin was recovered and purified to homogeneity. The complete amino-acid sequence of this protein was established. The isoelectric point (pI = 3.48), midpoint redox potential (Em = -0.412 V) and stability under denaturing conditions were also determined. This ferredoxin exhibits an unusual electrophoretic behavior, resulting in a very low apparent molecular mass between 2 and 3.5 kDa, even in the presence of high concentrations of urea. However, a molecular mass of 10,232 Da (apo-ferredoxin) is calculated from the sequence. Free thiol assays indicate the presence of a disulfide bridge in this protein. A small amount of ferredoxin was also found in another fraction during the purification procedure. The amino-acid sequence and properties of this minor ferredoxin were similar to those of the major ferredoxin. However, its solubility in ammonium sulfate and its reactivity with antibodies directed against spinach ferredoxin were different. Traces of flavodoxin were also recovered from the same fraction. The amount of flavodoxin was dramatically increased under iron-deficient growth conditions. An acidic isoelectric point was measured (pI = 3.76), close to that of ferredoxin. The midpoint redox potentials of flavodoxin are Em1 = -0.433 V and Em2 = -0.238 V at pH 7.8. Sequence comparison based on the 42 N-terminal amino acids indicates that Synechocystis 6803 flavodoxin most likely belongs to the long-chain class, despite an apparent molecular mass of 15 kDa determined by SDS-PAGE.

  9. Impacts of diurnal variation of ultraviolet-B and photosynthetically active radiation on phycobiliproteins of the hot-spring cyanobacterium Nostoc sp. strain HKAR-2.

    Science.gov (United States)

    Kannaujiya, Vinod K; Sinha, Rajeshwar P

    2017-01-01

    The effects of diurnal variation of photosynthetically active radiation (PAR; 400-700 nm) and ultraviolet-B (UV-B; 280-315 nm) radiation on phycobiliproteins (PBPs) and photosynthetic pigments (PP) have been studied in the hot-spring cyanobacterium Nostoc sp. strain HKAR-2. The variations in PBPs and PP were monitored by alternating light and dark under PAR, UV-B, and PAR + UV-B radiations over a period of 25 h. There was a decline in the amount of Chl a and PBPs during light periods of UV-B and PAR + UV-B and an increase during dark periods showing a circadian rhythm by destruction and resynthesis of pigment-protein complex. However, a marked induction in carotenoids was recorded during light periods of the same radiations. Moreover, the ratio of Chl a/PE and Chl a/PC was increased in dark periods showing the resynthesis of bleached Chl a. The wavelength shift in emission fluorescence of PBPs toward shorter wavelengths further indicated the bleaching and destruction of PBPs during light periods. Oxidative damage upon exposure to PAR, UV-B, and PAR + UV-B was alleviated by induction of antioxidative enzymes such as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). The studied cyanobacterium exhibits a significant increase in the activities of SOD, CAT, and APX upon exposure to UV-B and PAR + UV-B radiations. The results indicate that pigment-protein composition of Nostoc sp. stain HKAR-2 was significantly altered during diurnal variation of light/radiation, which might play an important role in optimization for their productivity in a particular cyanobacterium.

  10. Phosphoproteome of the cyanobacterium Synechocystis sp. PCC 6803 and its dynamics during nitrogen starvation.

    Directory of Open Access Journals (Sweden)

    Philipp eSpät

    2015-03-01

    Full Text Available Cyanobacteria have shaped the earth’s biosphere as the first oxygenic photoautotrophs and still play an important role in many ecosystems. The ability to adapt to changing environmental conditions is an essential characteristic in order to ensure survival. To this end, numerous studies have shown that bacteria use protein post-translational modifications such as Ser/Thr/Tyr phosphorylation in cell signalling, adaptation and regulation. Nevertheless, our knowledge of cyanobacterial phosphoproteomes and their dynamic response to environmental stimuli is relatively limited. In this study, we applied gel-free methods and high accuracy mass spectrometry towards the unbiased detection of Ser/Thr/Tyr phosphorylation events in the model cyanobacterium Synechocystis sp. PCC 6803. We could identify over 300 phosphorylation events in cultures grown on nitrate as exclusive nitrogen source. Chemical dimethylation labelling was applied to investigate proteome and phosphoproteome dynamics during nitrogen starvation. Our dataset describes the most comprehensive (phosphoproteome of Synechocystis to date, identifying 2,382 proteins and 183 phosphorylation events and quantifying 2,111 proteins and 148 phosphorylation events during nitrogen starvation. Global protein phosphorylation levels were increased in response to nitrogen depletion after 24 hours. Among the proteins with increased phosphorylation, the PII signalling protein showed the highest fold-change, serving as positive control. Other proteins with increased phosphorylation levels comprised functions in photosynthesis and in carbon and nitrogen metabolism. This study reveals dynamics of Synechocystis phosphoproteome in response to environmental stimuli and suggests an important role of protein Ser/Thr/Tyr phosphorylation in fundamental mechanisms of homeostatic control in cyanobacteria.

  11. Comparative genomic analyses of the cyanobacterium, Lyngbya aestuarii BL J, a powerful hydrogen producer.

    Directory of Open Access Journals (Sweden)

    Ankita eKothari

    2013-12-01

    Full Text Available The filamentous, non-heterocystous cyanobacterium Lyngbya aestuarii is an important contributor to marine intertidal microbial mats system worldwide. The recent isolate L. aestuarii BL J, is an unusually powerful hydrogen producer. Here we report a morphological, ultrastructural and genomic characterization of this strain to set the basis for future systems studies and applications of this organism. The filaments contain circa 17 μm wide trichomes, composed of stacked disk-like short cells (2 μm long, encased in a prominent, laminated exopolysaccharide sheath. Cellular division occurs by transversal centripetal growth of cross-walls, where several rounds of division proceed simultaneously. Filament division occurs by cell self-immolation of one or groups of cells (necridial cells at the breakage point. Short, sheath-less, motile filaments (hormogonia are also formed. Morphologically and phylogenetically L. aestuarii belongs to a clade of important cyanobacteria that include members of the marine Trichodesmiun and Hydrocoleum genera, as well as terrestrial Microcoleus vaginatus strains, and alkalyphilic strains of Arthrospira. A draft genome of strain BL J was compared to those of other cyanobacteria in order to ascertain some of its ecological constraints and biotechnological potential. The genome had an average GC content of 41.1 %. Of the 6.87 Mb sequenced, 6.44 Mb was present as large contigs (>10,000 bp. It contained 6515 putative protein-encoding genes, of which, 43 % encode proteins of known functional role, 26 % corresponded to proteins with domain or family assignments, 19.6 % encode conserved hypothetical proteins, and 11.3 % encode apparently unique hypothetical proteins. The strain’s genome reveals its adaptations to a life of exposure to intense solar radiation and desiccation. It likely employs the storage compounds, glycogen and cyanophycin but no polyhydroxyalkanoates, and can produce the osmolytes, trehalose and glycine

  12. Effect of Selected Plant Extracts and D- and L-Lysine on the Cyanobacterium Microcystis aeruginosa

    NARCIS (Netherlands)

    Lurling, M.F.L.L.W.; Oosterhout, J.F.X.

    2014-01-01

    We tested extracts from Fructus mume, Salvia miltiorrhiza and Moringa oleifera as well as L-lysine and D-Lysine as curative measures to rapidly suppress the cyanobacterium Microcystis aeruginosa NIVA-CYA 43. We tested these compounds under similar conditions to facilitate comparisons. We hypothesize

  13. Horizontal transfer of the nitrogen fixation gene cluster in the cyanobacterium Microcoleus chthonoplastes

    NARCIS (Netherlands)

    Bolhuis, H.; Severin, I.; Confurius-Guns, V.; Wollenzien, U.I.A.; Stal, L.J.

    2010-01-01

    The filamentous, non-heterocystous cyanobacterium Microcoleus chthonoplastes is a cosmopolitan organism, known to build microbial mats in a variety of different environments. Although most of these cyanobacterial mats are known for their capacity to fix dinitrogen, M. chthonoplastes has not been ass

  14. Highly plastic genome of Microcystis aeruginosa PCC 7806, a ubiquitous toxic freshwater cyanobacterium

    NARCIS (Netherlands)

    Frangeul, L.; Quillardet, P.; Castets, A.M.; Humbert, J.F.; Matthijs, H.C.P.; Cortez, D.; Tolonen, A.; Zhang, C.C.; Gribaldo, S.; Kehr, J.C.; Zilliges, Y.; Ziemert, N.; Becker, S.; Talla, E.; Latifi, A.; Billault, A.; Lepelletier, A.; Dittmann, E.; Bouchier, C.; Tandeau de Marsac, N.

    2008-01-01

    Background The colonial cyanobacterium Microcystis proliferates in a wide range of freshwater ecosystems and is exposed to changing environmental factors during its life cycle. Microcystis blooms are often toxic, potentially fatal to animals and humans, and may cause environmental problems. There ha

  15. Nostoc PCC7524, a cyanobacterium which contains five sequence-specific deoxyribonucleases

    NARCIS (Netherlands)

    Reaston, J.; Duybesteyn, M.G.C.; Waard, Adrian de

    Five nucleotide sequence-specific deoxyribonucleases present in cell-free extracts of the filamentous cyanobacterium Nostoc PCC7524 have been purified and characterized. One of these enzymes, designated Nsp(7524)I cleaves at a new kind of nucleotide sequence i.e. 5'-PuCATG λ Py-3'. The other four

  16. Horizontal transfer of the nitrogen fixation gene cluster in the cyanobacterium Microcoleus chthonoplastes

    NARCIS (Netherlands)

    Bolhuis, H.; Severin, I.; Confurius-Guns, V.; Wollenzien, U.I.A.; Stal, L.J.

    2010-01-01

    The filamentous, non-heterocystous cyanobacterium Microcoleus chthonoplastes is a cosmopolitan organism, known to build microbial mats in a variety of different environments. Although most of these cyanobacterial mats are known for their capacity to fix dinitrogen, M. chthonoplastes has not been

  17. Highly plastic genome of Microcystis aeruginosa PCC 7806, a ubiquitous toxic freshwater cyanobacterium

    NARCIS (Netherlands)

    Frangeul, L.; Quillardet, P.; Castets, A.M.; Humbert, J.F.; Matthijs, H.C.P.; Cortez, D.; Tolonen, A.; Zhang, C.C.; Gribaldo, S.; Kehr, J.C.; Zilliges, Y.; Ziemert, N.; Becker, S.; Talla, E.; Latifi, A.; Billault, A.; Lepelletier, A.; Dittmann, E.; Bouchier, C.; Tandeau de Marsac, N.

    2008-01-01

    Background The colonial cyanobacterium Microcystis proliferates in a wide range of freshwater ecosystems and is exposed to changing environmental factors during its life cycle. Microcystis blooms are often toxic, potentially fatal to animals and humans, and may cause environmental problems. There ha

  18. Horizontal transfer of the nitrogen fixation gene cluster in the cyanobacterium Microcoleus chthonoplastes

    NARCIS (Netherlands)

    Bolhuis, H.; Severin, I.; Confurius-Guns, V.; Wollenzien, U.I.A.; Stal, L.J.

    2010-01-01

    The filamentous, non-heterocystous cyanobacterium Microcoleus chthonoplastes is a cosmopolitan organism, known to build microbial mats in a variety of different environments. Although most of these cyanobacterial mats are known for their capacity to fix dinitrogen, M. chthonoplastes has not been ass

  19. Food quality of detritus derived from the filamentous cyanobacterium Oscillatoria limnetica for Daphnia galeata

    NARCIS (Netherlands)

    Repka, S.; Van der Vlies, M.; Vijverberg, J.

    1998-01-01

    Detritus derived from the filamentous cyanobacterium Oscillatoria limnetica was fed to Daphnia galeata. Detritus supported growth and reproduction comparable to that on the green alga Scenedesmus obliquus. The live filaments of O.limnetica were, however, of lower food quality. Biochemical parameters

  20. Competition and facilitation between the marine nitrogen-fixing cyanobacterium Cyanothece and its associated bacterial community

    NARCIS (Netherlands)

    Brauer, Verena S; Stomp, Maayke; Bouvier, Thierry; Fouilland, Eric; Leboulanger, Christophe; Confurius-Guns, Veronique; Weissing, Franz J; Stal, Lucas J; Huisman, Jef

    2015-01-01

    N2-fixing cyanobacteria represent a major source of new nitrogen and carbon for marine microbial communities, but little is known about their ecological interactions with associated microbiota. In this study we investigated the interactions between the unicellular N2-fixing cyanobacterium Cyanothece

  1. Hydrogen sulfide can inhibit and enhance oxygenic photosynthesis in a cyanobacterium from sulfidic springs

    NARCIS (Netherlands)

    Klatt, Judith M.; Haas, Sebastian; Yilmaz, Pelin; de Beer, Dirk; Polerecky, Lubos

    2015-01-01

    We used microsensors to investigate the combinatory effect of hydrogen sulfide (H2S) and light on oxygenic photosynthesis in biofilms formed by a cyanobacterium from sulfidic springs. We found that photosynthesis was both positively and negatively affected by H2S: (i) H2S accelerated the recovery of

  2. Evidence for a trimeric organization of the photosystem I complex from the thermophilic cyanobacterium Synechococcus sp.

    NARCIS (Netherlands)

    Boekema, E.J.; Dekker, J.P.; Heel, M.G. van; Rögner, M.; Saenger, W.; Witt, I.; Witt, H.T.

    1987-01-01

    A photosystem I (PS I) reaction center complex was isolated and purified from the cyanobacterium Synechococcus sp. The complex has a molecular mass of about 600 kDa and contains 120 Chl a molecules per photoactive Chl a1 (P-700). Electron micrographs show that the PS I complex has the shape of a dis

  3. Hydrogen sulfide can inhibit and enhance oxygenic photosynthesis in a cyanobacterium from sulfidic springs

    NARCIS (Netherlands)

    Klatt, Judith M.; Haas, Sebastian; Yilmaz, Pelin; de Beer, Dirk; Polerecky, Lubos

    We used microsensors to investigate the combinatory effect of hydrogen sulfide (H2S) and light on oxygenic photosynthesis in biofilms formed by a cyanobacterium from sulfidic springs. We found that photosynthesis was both positively and negatively affected by H2S: (i) H2S accelerated the recovery of

  4. The potential of cyanobacterium Schizothrix vaginata ISC108 in biodegradation of crude oil

    Directory of Open Access Journals (Sweden)

    M Safari

    2014-05-01

    Conclusions: It was found that cyanobacterium Schizothrix vaginata ISC108 has great potential in biodegradation of crude oil. Therefore, since oil is a product toxic to biological systems and is one of the main pollutants of bioecosystem, it has a great potential to be used as an indicator to eliminate pollution in contaminated areas.

  5. Effect of Selected Plant Extracts and D- and L-Lysine on the Cyanobacterium Microcystis aeruginosa

    NARCIS (Netherlands)

    Lurling, M.; Van Oosterhout, F.

    2014-01-01

    We tested extracts from Fructus mume, Salvia miltiorrhiza and Moringa oleifera as well as L-lysine and D-Lysine as curative measures to rapidly suppress the cyanobacterium Microcystis aeruginosa NIVA-CYA 43. We tested these compounds under similar conditions to facilitate comparisons. We

  6. Biological nitrogen fixation and biomass accumulation within poplar clones as a result of inoculations with diazotrophic endophyte consortia.

    Science.gov (United States)

    Knoth, Jenny L; Kim, Soo-Hyung; Ettl, Gregory J; Doty, Sharon L

    2014-01-01

    Sustainable production of biomass for bioenergy relies on low-input crop production. Inoculation of bioenergy crops with plant growth-promoting endophytes has the potential to reduce fertilizer inputs through the enhancement of biological nitrogen fixation (BNF). Endophytes isolated from native poplar growing in nutrient-poor conditions were selected for a series of glasshouse and field trials designed to test the overall hypothesis that naturally occurring diazotrophic endophytes impart growth promotion of the host plants. Endophyte inoculations contributed to increased biomass over uninoculated control plants. This growth promotion was more pronounced with multi-strain consortia than with single-strain inocula. Biological nitrogen fixation was estimated through (15)N isotope dilution to be 65% nitrogen derived from air (Ndfa). Phenotypic plasticity in biomass allocation and branch production observed as a result of endophyte inoculations may be useful in bioenergy crop breeding and engineering programs.

  7. A simple and efficient method for poly-3-hydroxybutyrate quantification in diazotrophic bacteria within 5 minutes using flow cytometry

    Directory of Open Access Journals (Sweden)

    L.P.S. Alves

    Full Text Available The conventional method for quantification of polyhydroxyalkanoates based on whole-cell methanolysis and gas chromatography (GC is laborious and time-consuming. In this work, a method based on flow cytometry of Nile red stained bacterial cells was established to quantify poly-3-hydroxybutyrate (PHB production by the diazotrophic and plant-associated bacteria, Herbaspirillum seropedicae and Azospirillum brasilense. The method consists of three steps: i cell permeabilization, ii Nile red staining, and iii analysis by flow cytometry. The method was optimized step-by-step and can be carried out in less than 5 min. The final results indicated a high correlation coefficient (R2=0.99 compared to a standard method based on methanolysis and GC. This method was successfully applied to the quantification of PHB in epiphytic bacteria isolated from rice roots.

  8. Novel labeling technique illustrates transfer of 15N2 from Sphagnum moss to vascular plants via diazotrophic nitrogen fixation

    Science.gov (United States)

    Thorp, N. R.; Vile, M. A.; Wieder, R.

    2013-12-01

    We used 15N2 gas to trace nitrogen (N) from biological N2-fixation to vascular plant uptake in an Alberta bog in order to determine if neighboring bog plants acquire recently fixed N from diazotrophs associating with Sphagnum mosses. Recent evidence indicates high rates of N2-fixation in Sphagnum mosses of Alberta bogs (Vile et al. 2013). Our previous work has shown that mosses can assimilate fixed N from associated diazotrophs as evidenced by the high N content of mosses despite minimal inputs from atmospheric deposition, retranslocation, and N mineralization. Therefore, the potential exists for vascular plants to obtain N from ';leaky' tissues of live mosses, however, this phenomenon has not been tested previously. Here we document the potential for relatively rapid transfer to vascular plants of N fixed by Sphagnum moss-associated diazotrophs. We utilized the novel approach of incubating mosses in 15N2 to allow the process of diazotrophic N2-fixation to mechanistically provide the 15N label, which is subsequently transferred to Sphagnum mosses. The potential for vascular bog natives to tap this N was assessed by planting the vascular plants in the labeled moss. Sphagnum mosses (upper 3 cm of live plants) were incubated in the presence of 98 atom % 15N2 gas for 48 hours. Two vascular plants common to Alberta bogs; Picea mariana and Vaccinium oxycoccus were then placed in the labeled mosses, where the mosses served as the substrate. Tissue samples from these plants were collected at three time points during the incubation; prior to 15N2 exposure (to determine natural abundance 15N), and at one and two months after 15N2 exposure. Roots and leaves were separated and run separately on a mass spectrometer to determine 15N concentrations. Sphagnum moss capitula obtained N from N2-fixation (δ15N of -2.43 × 0.40, 122.76 × 23.78, 224.92 × 68.37, 143.74 × 54.38 prior to, immediately after, and at 1 and 2 months after exposure to 15N2, respectively). Nitrogen was

  9. Arsenic Demethylation by a C·As Lyase in Cyanobacterium Nostoc sp. PCC 7120.

    Science.gov (United States)

    Yan, Yu; Ye, Jun; Xue, Xi-Mei; Zhu, Yong-Guan

    2015-12-15

    Arsenic, a ubiquitous toxic substance, exists mainly as inorganic forms in the environment. It is perceived that organoarsenicals can be demethylated and degraded into inorganic arsenic by microorganisms. Few studies have focused on the mechanism of arsenic demethylation in bacteria. Here, we investigated arsenic demethylation in a typical freshwater cyanobacterium Nostoc sp. PCC 7120. This bacterium was able to demethylate monomethylarsenite [MAs(III)] rapidly to arsenite [As(III)] and also had the ability to demethylate monomethylarsenate [MAs(V)] to As(III). The NsarsI encoding a C·As lyase responsible for MAs(III) demethylation was cloned from Nostoc sp. PCC 7120 and heterologously expressed in an As-hypersensitive strain Escherichia coli AW3110 (ΔarsRBC). Expression of NsarsI was shown to confer MAs(III) resistance through arsenic demethylation. The purified NsArsI was further identified and functionally characterized in vitro. NsArsI existed mainly as the trimeric state, and the kinetic data were well-fit to the Hill equation with K0.5 = 7.55 ± 0.33 μM for MAs(III), Vmax = 0.79 ± 0.02 μM min(-1), and h = 2.7. Both of the NsArsI truncated derivatives lacking the C-terminal 10 residues (ArsI10) or 23 residues (ArsI23) had a reduced ability of MAs(III) demethylation. These results provide new insights for understanding the important role of cyanobacteria in arsenic biogeochemical cycling in the environment.

  10. Enhanced biohydrogen production by the N{sub 2}-fixing cyanobacterium Anabaena siamensis strain TISTR 8012

    Energy Technology Data Exchange (ETDEWEB)

    Khetkorn, Wanthanee [Program of Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok, 10330 (Thailand); Laboratory of Cyanobacterial Biotechnology, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Phayathai Road, Bangkok, 10330 (Thailand); Department of Photochemistry and Molecular Science, Uppsala University, Box 523, SE-75120, Uppsala (Sweden); Lindblad, Peter [Department of Photochemistry and Molecular Science, Uppsala University, Box 523, SE-75120, Uppsala (Sweden); Incharoensakdi, Aran [Laboratory of Cyanobacterial Biotechnology, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Phayathai Road, Bangkok, 10330 (Thailand)

    2010-12-15

    The efficiency of hydrogen production depends on several factors. We focused on external conditions leading to enhanced hydrogen production when using the N{sub 2}-fixing cyanobacterium Anabaena siamensis TISTR 8012, a novel strain isolated from a rice paddy field in Thailand. In this study, we controlled key factors affecting hydrogen production such as cell age, light intensity, time of light incubation and source of carbon. Our results showed an enhanced hydrogen production when cells, at log phase, were adapted under N{sub 2}-fixing condition using 0.5% fructose as carbon source and a continuous illumination of 200 {mu}E m{sup -2} s{sup -1} for 12 h under anaerobic incubation. The maximum hydrogen production rate was 32 {mu}mol H{sub 2} mg chl a{sup -1} h{sup -1}. This rate was higher than that observed in the model organisms Anabaena PCC 7120, Nostoc punctiforme ATCC 29133 and Synechocystis PCC 6803. This higher production was likely caused by a higher nitrogenase activity since we observed an upregulation of nifD. The production did not increase after 12 h which was probably due to an increased activity of the uptake hydrogenase as evidenced by an increased hupL transcript level. Interestingly, a proper adjustment of light conditions such as intensity and duration is important to minimize both the photodamage of the cells and the uptake hydrogenase activity. Our results indicate that A. siamensis TISTR 8012 has a high potential for hydrogen production with the ability to utilize sugars as substrate to produce hydrogen. (author)

  11. Physiological and biochemical effects of allelochemical ethyl 2-methyl acetoacetate (EMA) on cyanobacterium Microcystis aeruginosa.

    Science.gov (United States)

    Hong, Yu; Hu, Hong-Ying; Li, Feng-Min

    2008-10-01

    The physiological and biochemical effects of an allelochemical ethyl 2-methyl acetoacetate (EMA) isolated from reed (Phragmites communis) on bloom-forming cyanobacterium, Microcystis aeruginosa, were investigated. EMA significantly inhibited the growth of M. aeruginosa in a concentration-dependent way. The metabolic indices (represented by esterase and total dehydrogenase activities), the cellular redox status (represented by the level of reactive oxygen species (ROS)), and the oxidative damage index (represented by the content of malondialdehyde (MDA), the product of membrane lipid peroxidation) were used to evaluate the physiological and biochemical changes in M. aeruginosa after EMA exposure. Esterase activity in M. aeruginosa did not change (P>0.05) after 2 h of exposure to EMA, but increased greatly after 24 and 48 h (PEMA exposure (>0.5 mg L(-1)) resulted in a remarkable loss of total dehydrogenase activity in M. aeruginosa after 4 h (PEMA caused a great increase in ROS level of the algal cells. At high EMA concentration (4 mg L(-1)), the ROS level was remarkably elevated to 1.91 times as much as that in the controls after 2 h. Increases in the ROS level also occurred after 24 and 48 h. The increase in lipid peroxidation of M. aeruginosa was dependent upon EMA concentration and the exposure time. After 40 h of exposure, the MDA content at 4 mg L(-1) of EMA reached approximately 3.5 times (PEMA; the increased metabolic activity perhaps reflects the fact that the resistance of cellular response system to the stress from EMA is initiated during EMA exposure, and the oxidative damage induced by EMA via the oxidation of ROS may be an important factor responsible for the inhibition of EMA on the growth of M. aeruginosa.

  12. Dependence of the cyanobacterium Prochlorococcus on hydrogen peroxide scavenging microbes for growth at the ocean's surface.

    Directory of Open Access Journals (Sweden)

    J Jeffrey Morris

    Full Text Available The phytoplankton community in the oligotrophic open ocean is numerically dominated by the cyanobacterium Prochlorococcus, accounting for approximately half of all photosynthesis. In the illuminated euphotic zone where Prochlorococcus grows, reactive oxygen species are continuously generated via photochemical reactions with dissolved organic matter. However, Prochlorococcus genomes lack catalase and additional protective mechanisms common in other aerobes, and this genus is highly susceptible to oxidative damage from hydrogen peroxide (HOOH. In this study we showed that the extant microbial community plays a vital, previously unrecognized role in cross-protecting Prochlorococcus from oxidative damage in the surface mixed layer of the oligotrophic ocean. Microbes are the primary HOOH sink in marine systems, and in the absence of the microbial community, surface waters in the Atlantic and Pacific Ocean accumulated HOOH to concentrations that were lethal for Prochlorococcus cultures. In laboratory experiments with the marine heterotroph Alteromonas sp., serving as a proxy for the natural community of HOOH-degrading microbes, bacterial depletion of HOOH from the extracellular milieu prevented oxidative damage to the cell envelope and photosystems of co-cultured Prochlorococcus, and facilitated the growth of Prochlorococcus at ecologically-relevant cell concentrations. Curiously, the more recently evolved lineages of Prochlorococcus that exploit the surface mixed layer niche were also the most sensitive to HOOH. The genomic streamlining of these evolved lineages during adaptation to the high-light exposed upper euphotic zone thus appears to be coincident with an acquired dependency on the extant HOOH-consuming community. These results underscore the importance of (indirect biotic interactions in establishing niche boundaries, and highlight the impacts that community-level responses to stress may have in the ecological and evolutionary outcomes for co

  13. Evolution of Anabaenopeptin Peptide Structural Variability in the Cyanobacterium Planktothrix

    Science.gov (United States)

    Entfellner, Elisabeth; Frei, Mark; Christiansen, Guntram; Deng, Li; Blom, Jochen; Kurmayer, Rainer

    2017-01-01

    Cyanobacteria are frequently involved in the formation of harmful algal blooms wherein, apart from the toxic microcystins, other groups of bioactive peptides are abundant as well, such as anabaenopeptins (APs). The APs are synthesized nonribosomally as cyclic hexapeptides with various amino acids at the exocyclic position. We investigated the presence and recombination of the AP synthesis gene cluster (apnA-E) through comparing 125 strains of the bloom-forming cyanobacterium Planktothrix spp., which were isolated from numerous shallow and deep water habitats in the temperate and tropical climatic zone. Ten ecologically divergent strains were purified and genome sequenced to compare their entire apnA-E gene cluster. In order to quantify apn gene distribution patterns, all the strains were investigated by PCR amplification of 2 kbp portions of the entire apn gene cluster without interruption. Within the 11 strains assigned to P. pseudagardhii, P. mougeotii, or P. tepida (Lineage 3), neither apnA-E genes nor remnants were observed. Within the P. agardhii/P. rubescens strains from shallow waters (Lineage 1, 52 strains), strains both carrying and lacking apn genes occurred, while among the strains lacking the apnA-E genes, the presence of the 5′end flanking region indicated a gene cluster deletion. Among the strains of the more derived deep water ecotype (Lineage 2, 62 strains), apnA-E genes were always present. A high similarity of apn genes of the genus Planktothrix when compared with strains of the genus Microcystis suggested its horizontal gene transfer during the speciation of P. agardhii/P. rubescens. Genetic analysis of the first (A1-) domain of the apnA gene, encoding synthesis of the exocyclic position of the AP molecule, revealed four genotype groups that corresponded with substrate activation. Groups of genotypes were either related to Arginine only, the coproduction of Arginine and Tyrosine or Arginine and Lysine, or even the coproduction of Arginine

  14. Dried Colony in Cyanobacterium, Nostoc sp. HK-01 — Several high Space Environment Tolerances for ``Tanpopo'' Mission

    Science.gov (United States)

    Tomita-Yokotani, K.; Kimura, S.; Kimura, Y.; Igarashi, Y.; Ajioka, R.; Sato, S.; Katoh, H.; Baba, K.

    2013-11-01

    A cyanobacterium, Nostoc sp. HK-01, has high several space environmental tolerance. Nostoc sp HK-01 would have high contribution for the “Tanpopo” mission in Japan Experimental Module of the International Space Station.

  15. Domain organization of photosystem II in membranes of the cyanobacterium Synechocystis PCC6803 investigated by electron microscopy

    NARCIS (Netherlands)

    Folea, I. Mihaela; Zhang, Pengpeng; Aro, Eva-Mari; Boekema, Egbert J.

    2008-01-01

    The supramolecular organization of photosystem II (PSII) complexes in the photosynthetic membrane of the cyanobacterium Synechocystis 6803 was studied by electron microscopy. After mild detergent solubilization, crystalline PSII arrays were extracted in which dimeric PSII particles associate in mult

  16. A high constitutive catalase activity confers resistance to methyl viologen-promoted oxidative stress in a mutant of the cyanobacterium Nostoc punctiforme ATCC 29133.

    Science.gov (United States)

    Moirangthem, Lakshmipyari Devi; Bhattacharya, Sudeshna; Stensjö, Karin; Lindblad, Peter; Bhattacharya, Jyotirmoy

    2014-04-01

    A spontaneous methyl viologen (MV)-resistant mutant of the nitrogen-fixing cyanobacterium Nostoc punctiforme ATCC 29133 was isolated and the major enzymatic antioxidants involved in combating MV-induced oxidative stress were evaluated. The mutant displayed a high constitutive catalase activity as a consequence of which, the intracellular level of reactive oxygen species in the mutant was lower than the wild type (N. punctiforme) in the presence of MV. The superoxide dismutase (SOD) activity that consisted of a SodA (manganese-SOD) and a SodB (iron-SOD) was not suppressed in the mutant following MV treatment. The mutant was, however, characterised by a lower peroxidase activity compared with its wild type, and its improved tolerance to externally added H₂O₂ could only be attributed to enhanced catalase activity. Furthermore, MV-induced toxic effects on the wild type such as (1) loss of photosynthetic performance assessed as maximal quantum yield of photosystem II, (2) nitrogenase inactivation, and (3) filament fragmentation and cell lysis were not observed in the mutant. These findings highlight the importance of catalase in preventing MV-promoted oxidative damage and cell death in the cyanobacterium N. punctiforme. Such oxidative stress resistant mutants of cyanobacteria are likely to be a better source of biofertilisers, as they can grow and fix nitrogen in an unhindered manner in agricultural fields that are often contaminated with the herbicide MV, also commonly known as paraquat.

  17. Response of biological soil crust diazotrophs to season, altered summer precipitation and year-round increased temperature in an arid grassland of the Colorado Plateau, USA

    Directory of Open Access Journals (Sweden)

    Chris M Yeager

    2012-10-01

    Full Text Available Biological soil crusts (biocrusts, which supply significant amounts of fixed nitrogen into terrestrial ecosystems worldwide (~33 Tg y-1, are likely to respond to changes in temperature and precipitation associated with climate change. Using nifH gene-based surveys, we explored variation in the diazotrophic community of biocrusts of the Colorado Plateau, USA in response to season (autumn vs. spring, as well as field manipulations that increased the frequency of small-volume precipitation events and year-round soil temperature. Abundance of nifH genes in biocrusts ranged from 3x106 – 1x108 g-1 soil, and nifH from heterocystous cyanobacteria closely related to Scytonema hyalinum, Spirirestis rafaelensis, and Nostoc commune comprised > 98% of the total. Although there was no apparent seasonal effect on total nifH gene abundance in the biocrusts, T-RFLP analysis revealed a strong seasonal pattern in nifH composition. Spirirestis nifH abundance was estimated to oscillate 1 to >2 orders of magnitude between autumn (low and spring (high. A year-round increase of soil temperature (2 − 3 °C had little effect on the diazotroph community structure over 2 years. Altered summer precipitation had little impact on diazotroph community structure over the first 1.5 years of the study, when natural background patterns across years and seasons superseded any treatment effects. However, after the second summer of treatments, nifH abundance was 2.6 fold lower in biocrusts receiving altered precipitation. Heterocystous cyanobacteria were apparently more resilient to altered precipitation than other cyanobacteria. The results demonstrate that diazotrophic community composition of biocrusts in this semi-arid grassland undergoes strong seasonal shifts and that the abundance of its dominant members decreased in response to more frequent, small-volume precipitation events.

  18. Response of biological soil crust diazotrophs to season, altered summer precipitation, and year-round increased temperature in an arid grassland of the Colorado Plateau, USA

    Science.gov (United States)

    Yeager, Chris M.; Kuske, Cheryl R.; Carney, Travis D.; Johnson, Shannon L.; Ticknor, Lawrence O.; Belnap, Jayne

    2012-01-01

    Biological soil crusts (biocrusts), which supply significant amounts of fixed nitrogen into terrestrial ecosystems worldwide (~33Tg y-1), are likely to respond to changes in temperature and precipitation associated with climate change. Using nifH gene-based surveys, we explored variation in the diazotrophic community of biocrusts of the Colorado Plateau, USA in response to season (autumn vs. spring), as well as field manipulations that increased the frequency of small volume precipitation events and year-round soil temperature. Abundance of nifH genes in biocrusts ranged from 3×106 to 1×8 g-1 soil, and nifH from heterocystous cyanobacteria closely related to Scytonema hyalinum, Spirirestis rafaelensis, and Nostoc commune comprised >98% of the total. Although there was no apparent seasonal effect on total nifH gene abundance in the biocrusts, T-RFLP analysis revealed a strong seasonal pattern in nifH composition. Spirirestis nifH abundance was estimated to oscillate 1 to >2 orders of magnitude between autumn (low) and spring (high). A year-round increase of soil temperature (2–3°C) had little effect on the diazotroph community structure over 2 years. Altered summer precipitation had little impact on diazotroph community structure over the first 1.5years of the study, when natural background patterns across years and seasons superseded any treatment effects. However, after the second summer of treatments, nifH abundance was 2.6-fold lower in biocrusts receiving altered precipitation. Heterocystous cyanobacteria were apparently more resilient to altered precipitation than other cyanobacteria. The results demonstrate that diazotrophic community composition of biocrusts in this semi-arid grassland undergoes strong seasonal shifts and that the abundance of its dominant members decreased in response to more frequent, small volume precipitation events.

  19. Introduction to the project VAHINE: VAriability of vertical and tropHIc transfer of diazotroph derived N in the south wEst Pacific

    Science.gov (United States)

    Bonnet, Sophie; Moutin, Thierry; Rodier, Martine; Grisoni, Jean-Michel; Louis, Francis; Folcher, Eric; Bourgeois, Bertrand; Boré, Jean-Michel; Renaud, Armelle

    2016-05-01

    On the global scale, N2 fixation provides the major external source of reactive nitrogen to the surface ocean, surpassing atmospheric and riverine inputs, and sustains ˜ 50 % of new primary production in oligotrophic environments. The main goal of the VAriability of vertical and tropHIc transfer of diazotroph derived N in the south wEst Pacific (VAHINE) project was to study the fate of nitrogen newly fixed by diazotrophs (or diazotroph-derived nitrogen) in oceanic food webs, and how it impacts heterotrophic bacteria, phytoplankton and zooplankton dynamics, stocks and fluxes of biogenic elements and particle export. Three large-volume ( ˜ 50 m3) mesocosms were deployed in a tropical oligotrophic ecosystem (the New Caledonia lagoon, south-eastern Pacific) and intentionally fertilized with ˜ 0.8 µM of dissolved inorganic phosphorus (DIP) to stimulate diazotrophy and follow subsequent ecosystem changes. VAHINE was a multidisciplinary project involving close collaborations between biogeochemists, molecular ecologist, chemists, marine opticians and modellers. This introductory paper describes in detail the scientific objectives of the project as well as the implementation plan: the mesocosm description and deployment, the selection of the study site (New Caledonian lagoon), and the logistical and sampling strategy. The main hydrological and biogeochemical conditions of the study site before the mesocosm deployment and during the experiment itself are described, and a general overview of the papers published in this special issue is presented.

  20. Biogeochemical and biological impacts of diazotroph blooms in a low-nutrient, low-chlorophyll ecosystem: synthesis from the VAHINE mesocosm experiment (New Caledonia)

    Science.gov (United States)

    Bonnet, Sophie; Baklouti, Melika; Gimenez, Audrey; Berthelot, Hugo; Berman-Frank, Ilana

    2016-08-01

    In marine ecosystems, biological N2 fixation provides the predominant external source of nitrogen (N; 140 ± 50 Tg N yr-1), contributing more than atmospheric and riverine inputs to the N supply. Yet the fate and magnitude of the newly fixed N, or diazotroph-derived N (hereafter named DDN) in marine ecosystems is poorly understood. Moreover, whether the DDN is preferentially and directly exported out of the photic zone, recycled by the microbial loop and/or transferred into larger organisms remains unclear. These questions were investigated in the framework of the VAHINE (VAriability of vertical and tropHIc transfer of diazotroph derived N in the south wEst Pacific) project. Triplicate large volume ( ˜ 50 m3) mesocosms were deployed in the tropical south-west Pacific coastal ocean (New Caledonia). The mesocosms were intentionally fertilized with ˜ 0.8 µM dissolved inorganic phosphorus (DIP) at the start of the experiment to stimulate diazotrophy. A total of 47 stocks, fluxes, enzymatic activities and diversity parameters were measured daily inside and outside the mesocosms by the 40 scientists involved in the project. The experiment lasted for 23 days and was characterized by two distinct and successive diazotroph blooms: a dominance of diatom-diazotroph associations (DDAs) during the first half of the experiment (days 2-14) followed by a bloom of unicellular cyanobacterial lineage C (UCYN-C during the second half of the experiment (days 15-23). These conditions provided a unique opportunity to compare the DDN transfer and export efficiency associated with different diazotrophs. Here we summarize the major experimental and modelling results obtained during the project and described in the VAHINE special issue, in particular those regarding the evolution of the main standing stocks, fluxes and biological characteristics over the 23-day experiment, the contribution of N2 fixation to export fluxes, the DDN released to dissolved pool and its transfer to the

  1. Environmental Factors Influencing Blooms of a Neurotoxic Stigonematalan Cyanobacterium Responsible for Avian Vacuolar Myelinopathy

    Science.gov (United States)

    2013-01-01

    killing waterbirds and raptors , to an epiphytic cyanobacterium which grows primarily on nonindigenous submerged aquatic vegetation (SAV). Water- birds...intramyelinic edema, in the organisms’ CNS tissue, most commonly the brain (Thomas et al. 1998). AVM-afflicted birds display erratic behavior ; clinical symptoms... feeding trials. Gavage trials with a methanol extract of the hydrilla-UCB demonstrated that extract would cause clinical symptoms and AVM lesions in

  2. Draft Genome Sequence of the Toxic Bloom-Forming Cyanobacterium Aphanizomenon flos-aquae NIES-81

    OpenAIRE

    Cao, Huansheng; Shimura, Yohei; Masanobu, Kawachi; Yin, Yanbin

    2014-01-01

    Aphanizomenon flos-aquae is a toxic filamentous cyanobacterium that causes water blooms in freshwaters across the globe. We present the draft genome sequence of the A. flos-aquae strain NIES-81, which was determined by 454 pyrosequencing technology. The draft genome is ~5.7 Mb, containing 5,802 predicted protein-coding genes and 58 RNA genes, with a G+C content of 38.5%.

  3. Draft Genome Sequence of the Toxic Bloom-Forming Cyanobacterium Aphanizomenon flos-aquae NIES-81.

    Science.gov (United States)

    Cao, Huansheng; Shimura, Yohei; Masanobu, Kawachi; Yin, Yanbin

    2014-02-13

    Aphanizomenon flos-aquae is a toxic filamentous cyanobacterium that causes water blooms in freshwaters across the globe. We present the draft genome sequence of the A. flos-aquae strain NIES-81, which was determined by 454 pyrosequencing technology. The draft genome is ~5.7 Mb, containing 5,802 predicted protein-coding genes and 58 RNA genes, with a G+C content of 38.5%.

  4. Anoxygenic Photosynthesis Controls Oxygenic Photosynthesis in a Cyanobacterium from a Sulfidic Spring

    OpenAIRE

    Klatt, Judith M.; Al-Najjar, Mohammad A. A.; Yilmaz, Pelin; Lavik, Gaute; de Beer, Dirk; Polerecky, Lubos

    2015-01-01

    Before the Earth's complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39,...

  5. Proteome-Wide Analysis and Diel Proteomic Profiling of the Cyanobacterium Arthrospira platensis PCC 8005

    OpenAIRE

    2014-01-01

    The filamentous cyanobacterium Arthrospira platensis has a long history of use as a food supply and it has been used by the European Space Agency in the MELiSSA project, an artificial microecosystem which supports life during long-term manned space missions. This study assesses progress in the field of cyanobacterial shotgun proteomics and light/dark diurnal cycles by focusing on Arthrospira platensis. Several fractionation workflows including gel-free and gel-based protein/peptide fractionat...

  6. Regulation of Three Nitrogenase Gene Clusters in the Cyanobacterium Anabaena variabilis ATCC 29413

    OpenAIRE

    Teresa Thiel; Pratte, Brenda S.

    2014-01-01

    The filamentous cyanobacterium Anabaena variabilis ATCC 29413 fixes nitrogen under aerobic conditions in specialized cells called heterocysts that form in response to an environmental deficiency in combined nitrogen. Nitrogen fixation is mediated by the enzyme nitrogenase, which is very sensitive to oxygen. Heterocysts are microxic cells that allow nitrogenase to function in a filament comprised primarily of vegetative cells that produce oxygen by photosynthesis. A. variabilis is unique among...

  7. Engineering of photosynthetic mannitol biosynthesis from CO2 in a cyanobacterium

    DEFF Research Database (Denmark)

    Jacobsen, Jacob Hedemand; Frigaard, Niels-Ulrik

    2014-01-01

    d-Mannitol (hereafter denoted mannitol) is used in the medical and food industry and is currently produced commercially by chemical hydrogenation of fructose or by extraction from seaweed. Here, the marine cyanobacterium Synechococcus sp. PCC 7002 was genetically modified to photosynthetically...... concentration of 1.1gmannitolL(-1) and a production rate of 0.15gmannitolL(-1)day(-1). This system may be useful for biosynthesis of valuable sugars and sugar derivatives from CO2 in cyanobacteria....

  8. Aeruginazole A, a novel thiazole-containing cyclopeptide from the cyanobacterium Microcystis sp.

    Science.gov (United States)

    Raveh, Avi; Carmeli, Shmuel

    2010-08-01

    A novel thiazole-containing cyclic peptide, aeruginazole A (1), was isolated from the cyanobacterium Microcystis sp. strain (IL-323), which was collected from a water reservoir near Kfar-Yehoshua, Valley of Armageddon, Israel. The planar structure of aeruginazole A was established using homonuclear and inverse-heteronuclear 2D NMR techniques, as well as high-resolution mass spectrometry. The absolute configuration of the asymmetric centers was determined using Marfey's method. Aeruginazole A potently inhibited Bacillus subtilis.

  9. Cyanobacterium Microcystis aeruginosa response to pentachlorophenol and comparison with that of the microalga Chlorella vulgaris.

    Science.gov (United States)

    de Morais, Paulo; Stoichev, Teodor; Basto, M Clara P; Ramos, V; Vasconcelos, V M; Vasconcelos, M Teresa S D

    2014-04-01

    Pentachlorophenol (PCP) effects on a strain of the cyanobacterium Microcystis aeruginosa were investigated at laboratory scale. This is the first systematic ecotoxicity study of the effects of PCP on an aquatic cyanobacterium. The microalga Chlorella vulgaris was studied in the same conditions as the cyanobacterium, in order to compare the PCP toxicity and its removal by the species. The cells were exposed to environmental levels of PCP during 10 days, in Fraquil culture medium, at nominal concentrations from 0.01 to 1000 μg L(-1), to the cyanobacterium, and 0.01 to 5000 μg L(-1), to the microalga. Growth was assessed by area under growth curve (AUC, optical density vs time) and chlorophyll a content (chla). The toxicity profiles of the two species were very different. The calculated effective concentrations EC20 and EC50 were much lower to M. aeruginosa, and its growth inhibition expressed by chla was concentration-dependent while by AUC was not concentration-dependent. The cells might continue to divide even with lower levels of chla. The number of C. vulgaris cells decreased with the PCP concentration without major impact on the chla. The effect of PCP on M. aeruginosa is hormetic: every concentration studied was toxic except 1 μg L(-1), which promoted its growth. The legal limit of PCP set by the European Union for surface waters (1 μg L(-1)) should be reconsidered since a toxic cyanobacteria bloom might occur. The study of the removal of PCP from the culture medium by the two species is an additional novelty of this work. M. aeruginosa could remove part of the PCP from the medium, at concentrations where toxic effects were observed, while C. vulgaris stabilized it.

  10. Cell envelope components influencing filament length in the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Burnat, Mireia; Schleiff, Enrico; Flores, Enrique

    2014-12-01

    Heterocyst-forming cyanobacteria grow as chains of cells (known as trichomes or filaments) that can be hundreds of cells long. The filament consists of individual cells surrounded by a cytoplasmic membrane and peptidoglycan layers. The cells, however, share a continuous outer membrane, and septal proteins, such as SepJ, are important for cell-cell contact and filament formation. Here, we addressed a possible role of cell envelope components in filamentation, the process of producing and maintaining filaments, in the model cyanobacterium Anabaena sp. strain PCC 7120. We studied filament length and the response of the filaments to mechanical fragmentation in a number of strains with mutations in genes encoding cell envelope components. Previously published peptidoglycan- and outer membrane-related gene mutants and strains with mutations in two genes (all5045 and alr0718) encoding class B penicillin-binding proteins isolated in this work were used. Our results show that filament length is affected in most cell envelope mutants, but the filaments of alr5045 and alr2270 gene mutants were particularly fragmented. All5045 is a dd-transpeptidase involved in peptidoglycan elongation during cell growth, and Alr2270 is an enzyme involved in the biosynthesis of lipid A, a key component of lipopolysaccharide. These results indicate that both components of the cell envelope, the murein sacculus and the outer membrane, influence filamentation. As deduced from the filament fragmentation phenotypes of their mutants, however, none of these elements is as important for filamentation as the septal protein SepJ.

  11. Genome-derived insights into the biology of the hepatotoxic bloom-forming cyanobacterium Anabaena sp. strain 90.

    Science.gov (United States)

    Wang, Hao; Sivonen, Kaarina; Rouhiainen, Leo; Fewer, David P; Lyra, Christina; Rantala-Ylinen, Anne; Vestola, Johanna; Jokela, Jouni; Rantasärkkä, Kaisa; Li, Zhijie; Liu, Bin

    2012-11-13

    Cyanobacteria can form massive toxic blooms in fresh and brackish bodies of water and are frequently responsible for the poisoning of animals and pose a health risk for humans. Anabaena is a genus of filamentous diazotrophic cyanobacteria commonly implicated as a toxin producer in blooms in aquatic ecosystems throughout the world. The biology of bloom-forming cyanobacteria is poorly understood at the genome level. Here, we report the complete sequence and comprehensive annotation of the bloom-forming Anabaena sp. strain 90 genome. It comprises two circular chromosomes and three plasmids with a total size of 5.3 Mb, encoding a total of 4,738 genes. The genome is replete with mobile genetic elements. Detailed manual annotation demonstrated that almost 5% of the gene repertoire consists of pseudogenes. A further 5% of the genome is dedicated to the synthesis of small peptides that are the products of both ribosomal and nonribosomal biosynthetic pathways. Inactivation of the hassallidin (an antifungal cyclic peptide) biosynthetic gene cluster through a deletion event and a natural mutation of the buoyancy-permitting gvpG gas vesicle gene were documented. The genome contains a large number of genes encoding restriction-modification systems. Two novel excision elements were found in the nifH gene that is required for nitrogen fixation. Genome analysis demonstrated that this strain invests heavily in the production of bioactive compounds and restriction-modification systems. This well-annotated genome provides a platform for future studies on the ecology and biology of these important bloom-forming cyanobacteria.

  12. Genome-derived insights into the biology of the hepatotoxic bloom-forming cyanobacterium Anabaena sp. strain 90

    Directory of Open Access Journals (Sweden)

    Wang Hao

    2012-11-01

    Full Text Available Abstract Background Cyanobacteria can form massive toxic blooms in fresh and brackish bodies of water and are frequently responsible for the poisoning of animals and pose a health risk for humans. Anabaena is a genus of filamentous diazotrophic cyanobacteria commonly implicated as a toxin producer in blooms in aquatic ecosystems throughout the world. The biology of bloom-forming cyanobacteria is poorly understood at the genome level. Results Here, we report the complete sequence and comprehensive annotation of the bloom-forming Anabaena sp. strain 90 genome. It comprises two circular chromosomes and three plasmids with a total size of 5.3 Mb, encoding a total of 4,738 genes. The genome is replete with mobile genetic elements. Detailed manual annotation demonstrated that almost 5% of the gene repertoire consists of pseudogenes. A further 5% of the genome is dedicated to the synthesis of small peptides that are the products of both ribosomal and nonribosomal biosynthetic pathways. Inactivation of the hassallidin (an antifungal cyclic peptide biosynthetic gene cluster through a deletion event and a natural mutation of the buoyancy-permitting gvpG gas vesicle gene were documented. The genome contains a large number of genes encoding restriction-modification systems. Two novel excision elements were found in the nifH gene that is required for nitrogen fixation. Conclusions Genome analysis demonstrated that this strain invests heavily in the production of bioactive compounds and restriction-modification systems. This well-annotated genome provides a platform for future studies on the ecology and biology of these important bloom-forming cyanobacteria.

  13. Adaptation strategies of the sheathed cyanobacterium Lyngbya majuscula to ultraviolet-B.

    Science.gov (United States)

    Mandal, Sikha; Rath, Jnanendra; Adhikary, Siba Prasad

    2011-02-01

    Lyngbya majuscula is a dominant organism in the east coast of India forming characteristic mat in dried saline soils simultaneously exposed to solar radiation of the tropics. Studies on the growth response, changes in the spectral properties of the methanolic extract and protein profile of this estuarine sheathed cyanobacterium to UV-B revealed existence of effective adaptation mechanism to withstand prolonged UV-B radiation. Carotenoids along with MAAs of the organism was increased with increase in UV irradiation. Increase in thickness of the mucilaginous sheath layer as well as cellular carbohydrate content was observed upon exposure to prolonged UV-B dose. Induction of 21 and 33 kDa low molecular weight proteins, and a 99 kDa protein together with formation of distinct multilayered sheath embedding trichomes with granulated cells were the adaptive features of the organism to cope with UV-B stress. The organism was considerably revived after incubating the irradiated cells in mineral medium under florescent light and in the dark suggesting existence of photoreactivation and dark repair in this cyanobacterium. However more experiments are needed to establish the existence of photoreactivation and dark repair mechanism in the studied cyanobacterium.

  14. Role of manganese in protection against oxidative stress under iron starvation in cyanobacterium Anabaena 7120.

    Science.gov (United States)

    Kaushik, Manish Singh; Srivastava, Meenakshi; Verma, Ekta; Mishra, Arun Kumar

    2015-06-01

    The cyanobacterium Anabaena sp. PCC 7120 was grown in presence and absence of iron to decipher the role of manganese in protection against the oxidative stress under iron starvation and growth, manganese uptake kinetics, antioxidative enzymes, lipid peroxidation, electrolyte leakage, thiol content, total peroxide, proline and NADH content was investigated. Manganese supported the growth of cyanobacterium Anabaena 7120 under iron deprived conditions where maximum uptake rate of manganese was observed with lower K(m) and higher V(max) values. Antioxidative enzymes were also found to be elevated in iron-starved conditions. Estimation of lipid peroxidation and electrolyte leakage depicted the role of manganese in stabilizing the integrity of the membrane which was considered as the prime target of oxygen free radicals in oxidative stress. The levels of total peroxide, thiol, proline and NADH content, which are the representative of oxidative stress response in Anabaena 7120, were also showed increasing trends in iron starvation. Hence, the results discerned, clearly suggested the role of manganese in protection against the oxidative stress in cyanobacterium Anabaena 7120 under iron starvation either due to its antioxidative properties or involvement as cofactor in a number of antioxidative enzymes.

  15. Differential responses of dinitrogen fixation, diazotrophic cyanobacteria and ammonia oxidation reveal a potential warming-induced imbalance of the N-cycle in biological soil crusts

    Science.gov (United States)

    Zhou, Xiaobing; Smith, Hilda J.; Giraldo Silva, Ana; Belnap, Jayne; Garcia-Pichel, Ferran

    2017-01-01

    N2 fixation and ammonia oxidation (AO) are the two most important processes in the nitrogen (N) cycle of biological soil crusts (BSCs). We studied the short-term response of acetylene reduction assay (ARA) rates, an indicator of potential N2 fixation, and AO rates to temperature (T, -5°C to 35°C) in BSC of different successional stages along the BSC ecological succession and geographic origin (hot Chihuahuan and cooler Great Basin deserts). ARA in all BSCs increased with T until saturation occurred between 15 and 20°C, and declined at 30–35°C. Culture studies using cyanobacteria isolated from these crusts indicated that the saturating effect was traceable to their inability to grow well diazotrophically within the high temperature range. Below saturation, temperature response was exponential, with Q10 significantly different in the two areas (~ 5 for Great Basin BSCs; 2–3 for Chihuahuan BSCs), but similar between the two successional stages. However, in contrast to ARA, AO showed a steady increase to 30–35°C in Great Basin, and Chihuhuan BSCs showed no inhibition at any tested temperature. The T response of AO also differed significantly between Great Basin (Q10 of 4.5–4.8) and Chihuahuan (Q10 of 2.4–2.6) BSCs, but not between successional stages. Response of ARA rates to T did not differ from that of AO in either desert. Thus, while both processes scaled to T in unison until 20°C, they separated to an increasing degree at higher temperature. As future warming is likely to occur in the regions where BSCs are often the dominant living cover, this predicted decoupling is expected to result in higher proportion of nitrates in soil relative to ammonium. As nitrate is more easily lost as leachate or to be reduced to gaseous forms, this could mean a depletion of soil N over large landscapes globally.

  16. Significance of diazotrophic plant growth-promoting Herbaspirillum sp. GW103 on phytoextraction of Pband Zn by Zea mays L.

    Science.gov (United States)

    Praburaman, Loganathan; Park, Sung-Hee; Cho, Min; Lee, Kui-Jae; Ko, Jeong-Ae; Han, Sang-Sub; Lee, Sang-Hyun; Kamala-Kannan, Seralathan; Oh, Byung-Taek

    2017-01-01

    Microbe-assisted phytoremediation has been considered a promising measure for the remediation of heavy metal-polluted soil. The aim of this study was to assess the effect of diazotrophic plant growth-promoting Herbaspirillum sp. GW103 on growth and lead (Pb) and zinc (Zn) accumulation in Zea mays L. The strain GW103 exhibited plant growth-promoting traits such as indole-3-acetic acid, siderophores, and 1-aminocyclopropane-1-carboxylic deaminase. Treatment of Z. mays L. plants with GW103 significantly increased 19, 31, and 52% of plant biomass and 10, 50, and 126% of chlorophyll a contents in Pb, Zn, and Pb + Zn-amended soils, respectively. Similarly, the strain GW103 significantly increased Pb and Zn accumulation in shoots and roots of Z. mays L., which were 77 and 25% in Pb-amended soil, 42 and 73% in Zn-amended soil, and 27 and 84% in Pb + Zn-amended soil. Furthermore, addition of GW103 increased 8, 12, and 7% of total protein content, catalase, and superoxide dismutase levels, respectively, in Z. mays L. plants. The results pointed out that isolate GW103 could potentially reduce the phytotoxicity of metals and increase Pb and Zn accumulation in Z. mays L. plant.

  17. Ammonia-Oligotrophic and Diazotrophic Heavy Metal-Resistant Serratia liquefaciens Strains from Pioneer Plants and Mine Tailings.

    Science.gov (United States)

    Zelaya-Molina, Lily X; Hernández-Soto, Luis M; Guerra-Camacho, Jairo E; Monterrubio-López, Ricardo; Patiño-Siciliano, Alfredo; Villa-Tanaca, Lourdes; Hernández-Rodríguez, César

    2016-08-01

    Mine tailings are man-made environments characterized by low levels of organic carbon and assimilable nitrogen, as well as moderate concentrations of heavy metals. For the introduction of nitrogen into these environments, a key role is played by ammonia-oligotrophic/diazotrophic heavy metal-resistant guilds. In mine tailings from Zacatecas, Mexico, Serratia liquefaciens was the dominant heterotrophic culturable species isolated in N-free media from bulk mine tailings as well as the rhizosphere, roots, and aerial parts of pioneer plants. S. liquefaciens strains proved to be a meta-population with high intraspecific genetic diversity and a potential to respond to these extreme conditions. The phenotypic and genotypic features of these strains reveal the potential adaptation of S. liquefaciens to oligotrophic and nitrogen-limited mine tailings with high concentrations of heavy metals. These features include ammonia-oligotrophic growth, nitrogen fixation, siderophore and indoleacetic acid production, phosphate solubilization, biofilm formation, moderate tolerance to heavy metals under conditions of diverse nitrogen availability, and the presence of zntA, amtB, and nifH genes. The acetylene reduction assay suggests low nitrogen-fixing activity. The nifH gene was harbored in a plasmid of ∼60 kb and probably was acquired by a horizontal gene transfer event from Klebsiella variicola.

  18. Evidence for protection of nitrogenase from O(2) by colony structure in the aerobic diazotroph Gluconacetobacter diazotrophicus.

    Science.gov (United States)

    Dong, Z; Zelmer, C D; Canny, M J; McCully, M E; Luit, B; Pan, B; Faustino, R S; Pierce, G N; Vessey, J K

    2002-08-01

    Gluconacetobacter diazotrophicus is an endophytic diazotroph of sugarcane which exhibits nitrogenase activity when growing in colonies on solid media. Nitrogenase activity of G. diazotrophicus colonies can adapt to changes in atmospheric partial pressure of oxygen (pO(2)). This paper investigates whether colony structure and the position of G. diazotrophicus cells in the colonies are components of the bacterium's ability to maintain nitrogenase activity at a variety of atmospheric pO(2) values. Colonies of G. diazotrophicus were grown on solid medium at atmospheric pO(2) of 2 and 20 kPa. Imaging of live, intact colonies by confocal laser scanning microscopy and of fixed, sectioned colonies by light microscopy revealed that at 2 kPa O(2) the uppermost bacteria in the colony were very near the upper surface of the colony, while the uppermost bacteria of colonies cultured at 20 kPa O(2) were positioned deeper in the mucilaginous matrix of the colony. Disruption of colony structure by physical manipulation or due to 'slumping' associated with colony development resulted in significant declines in nitrogenase activity. These results support the hypothesis that G. diazotrophicus utilizes the path-length of colony mucilage between the atmosphere and the bacteria to achieve a flux of O(2) that maintains aerobic respiration while not inhibiting nitrogenase activity.

  19. Structural interaction between GFP-labeled diazotrophic endophytic bacterium Herbaspirillum seropedicae RAM10 and pineapple plantlets 'Vitória'

    Directory of Open Access Journals (Sweden)

    Lílian Estrela Borges Baldotto

    2011-03-01

    Full Text Available The events involved in the structural interaction between the diazotrophic endophytic bacterium Herbaspirillum seropedicae, strain RAM10, labeled with green fluorescent protein, and pineapple plantlets 'Vitória' were evaluated by means of bright-field and fluorescence microscopy, combined with scanning electron microscopy for 28 days after inoculation. After 6 hours of inoculation, H. seropedicae was already adhered to the roots, colonizing mainly root hair surface and bases, followed by epidermal cell wall junctions. Bacteria adherence in the initial periods occurred mainly in the form of solitary cells and small aggregates with pleomorphic cells. Bacteria infection of root tissue occurred through the cavities caused by the disruption of epidermal cells during the emergence of lateral roots and the endophytic establishment by the colonization of intercellular spaces of the cortical parenchyma. Moreover, within 1 day after inoculation the bacteria were colonizing the shoots. In this region, the preferred sites of epiphytic colonization were epidermal cell wall junctions, peltate scutiform trichomes and non-glandular trichomes. Subsequently, the bacteria occupied the outer periclinal walls of epidermal cells and stomata. The penetration into the shoot occurred passively through stoma aperture followed by the endophytic establishment on the substomatal chambers and spread to the intercellular spaces of spongy chlorenchyma. After 21 days of inoculation, bacterial biofilm were seen at the root hair base and on epidermal cell wall surface of root and leaf, also confirming the epiphytic nature of H. seropedicae.

  20. Physiological and proteomic analysis of salinity tolerance of the halotolerant cyanobacterium Anabaena sp.

    Science.gov (United States)

    Yadav, Ravindra Kumar; Thagela, Preeti; Tripathi, Keshawanand; Abraham, G

    2016-09-01

    The halotolerant cyanobacterium Anabaena sp was grown under NaCl concentration of 0, 170 and 515 mM and physiological and proteomic analysis was performed. At 515 mM NaCl the cyanobacterium showed reduced photosynthetic activities and significant increase in soluble sugar content, proline and SOD activity. On the other hand Anabaena sp grown at 170 mM NaCl showed optimal growth, photosynthetic activities and comparatively low soluble sugar content, proline accumulation and SOD activity. The intracellular Na(+) content of the cells increased both at 170 and 515 mM NaCl. In contrast, the K(+) content of the cyanobacterium Anabaena sp remained stable in response to growth at identical concentration of NaCl. While cells grown at 170 mM NaCl showed highest intracellular K(+)/Na(+) ratio, salinity level of 515 mM NaCl resulted in reduced ratio of K(+)/Na(+). Proteomic analysis revealed 50 salt-responsive proteins in the cyanobacterium Anabaena sp under salt treatment compared with control. Ten protein spots were subjected to MALDI-TOF-MS/MS analysis and the identified proteins are involved in photosynthesis, protein folding, cell organization and energy metabolism. Differential expression of proteins related to photosynthesis, energy metabolism was observed in Anabaena sp grown at 170 mM NaCl. At 170 mM NaCl increased expression of photosynthesis related proteins and effective osmotic adjustment through increased antioxidant enzymes and modulation of intracellular ions contributed to better salinity tolerance and optimal growth. On the contrary, increased intracellular Na(+) content coupled with down regulation of photosynthetic and energy related proteins resulted in reduced growth at 515 mM NaCl. Therefore reduced growth at 515 mM NaCl could be due to accumulation of Na(+) ions and requirement to maintain higher organic osmolytes and antioxidants which is energy intensive. The results thus show that the basis of salt tolerance is different when the

  1. Halotolerant cyanobacterium Aphanothece halophytica contains NapA-type Na+/H+ antiporters with novel ion specificity that are involved in salt tolerance at alkaline pH.

    Science.gov (United States)

    Wutipraditkul, Nuchanat; Waditee, Rungaroon; Incharoensakdi, Aran; Hibino, Takashi; Tanaka, Yoshito; Nakamura, Tatsunosuke; Shikata, Masamitsu; Takabe, Tetsuko; Takabe, Teruhiro

    2005-08-01

    Aphanothece halophytica is a halotolerant alkaliphilic cyanobacterium which can grow at NaCl concentrations up to 3.0 M and at pH values up to 11. The genome sequence revealed that the cyanobacterium Synechocystis sp. strain PCC 6803 contains five putative Na+/H+ antiporters, two of which are homologous to NhaP of Pseudomonas aeruginosa and three of which are homologous to NapA of Enterococcus hirae. The physiological and functional properties of NapA-type antiporters are largely unknown. One of NapA-type antiporters in Synechocystis sp. strain PCC 6803 has been proposed to be essential for the survival of this organism. In this study, we examined the isolation and characterization of the homologous gene in Aphanothece halophytica. Two genes encoding polypeptides of the same size, designated Ap-napA1-1 and Ap-napA1-2, were isolated. Ap-NapA1-1 exhibited a higher level of homology to the Synechocystis ortholog (Syn-NapA1) than Ap-NapA1-2 exhibited. Ap-NapA1-1, Ap-NapA1-2, and Syn-NapA1 complemented the salt-sensitive phenotypes of an Escherichia coli mutant and exhibited strongly pH-dependent Na+/H+ and Li+/H+ exchange activities (the highest activities were at alkaline pH), although the activities of Ap-NapA1-2 were significantly lower than the activities of the other polypeptides. Only one these polypeptides, Ap-NapA1-2, complemented a K+ uptake-deficient E. coli mutant and exhibited K+ uptake activity. Mutagenesis experiments suggested the importance of Glu129, Asp225, and Asp226 in the putative transmembrane segment and Glu142 in the loop region for the activity. Overexpression of Ap-NapA1-1 in the freshwater cyanobacterium Synechococcus sp. strain PCC 7942 enhanced the salt tolerance of cells, especially at alkaline pH. These findings indicate that A. halophytica has two NapA1-type antiporters which exhibit different ion specificities and play an important role in salt tolerance at alkaline pH.

  2. Seawater cultivation of freshwater cyanobacterium Synechocystis sp. PCC 6803 drastically alters amino acid composition and glycogen metabolism

    Directory of Open Access Journals (Sweden)

    Hiroko eIijima

    2015-04-01

    Full Text Available Water use assessment is important for bioproduction using cyanobacteria. For eco-friendly reasons, seawater should preferably be used for cyanobacteria cultivation instead of freshwater. In this study, we demonstrated that the freshwater unicellular cyanobacterium Synechocystis sp. PCC 6803 could be grown in a medium based on seawater. The Synechocystis wild-type strain grew well in an artificial seawater (ASW medium supplemented with nitrogen and phosphorus sources. The addition of HEPES buffer improved cell growth overall, although the growth in ASW medium was inferior to that in the synthetic BG-11 medium. The levels of proteins involved in sugar metabolism changed depending on the culture conditions. The biosynthesis of several amino acids including aspartate, glutamine, glycine, proline, ornithine, and lysine, was highly up-regulated by cultivation in ASW. Two types of natural seawater (NSW were also made available for the cultivation of Synechocystis cells, with supplementation of both nitrogen and phosphorus sources. These results revealed the potential use of seawater for the cultivation of freshwater cyanobacteria, which would help to reduce freshwater consumption during biorefinery using cyanobacteria.

  3. Seawater cultivation of freshwater cyanobacterium Synechocystis sp. PCC 6803 drastically alters amino acid composition and glycogen metabolism

    Science.gov (United States)

    Iijima, Hiroko; Nakaya, Yuka; Kuwahara, Ayuko; Hirai, Masami Yokota; Osanai, Takashi

    2015-01-01

    Water use assessment is important for bioproduction using cyanobacteria. For eco-friendly reasons, seawater should preferably be used for cyanobacteria cultivation instead of freshwater. In this study, we demonstrated that the freshwater unicellular cyanobacterium Synechocystis sp. PCC 6803 could be grown in a medium based on seawater. The Synechocystis wild-type strain grew well in an artificial seawater (ASW) medium supplemented with nitrogen and phosphorus sources. The addition of HEPES buffer improved cell growth overall, although the growth in ASW medium was inferior to that in the synthetic BG-11 medium. The levels of proteins involved in sugar metabolism changed depending on the culture conditions. The biosynthesis of several amino acids including aspartate, glutamine, glycine, proline, ornithine, and lysine, was highly up-regulated by cultivation in ASW. Two types of natural seawater (NSW) were also made available for the cultivation of Synechocystis cells, with supplementation of both nitrogen and phosphorus sources. These results revealed the potential use of seawater for the cultivation of freshwater cyanobacteria, which would help to reduce freshwater consumption during biorefinery using cyanobacteria. PMID:25954257

  4. Ocorrência de bactérias diazotróficas associadas a cultivares de sorgo forrageiro Occurrence of diazotrophic bacteria associated with forage sorghum cultivars

    Directory of Open Access Journals (Sweden)

    Clarissa Bergamaschi

    2007-06-01

    Full Text Available O presente estudo objetivou avaliar a ocorrência de bactérias diazotróficas associadas ao sorgo, selecionar cultivares eficientes na associação com bactérias diazotróficas e identificar os isolados mais eficientes em fixar nitrogênio atmosférico (N² e produzir ácido indol-acético (AIA. Utilizaram-se 14 cultivares de sorgo forrageiro em vasos, com dois níveis de N: 0 e 130kg ha-1 de N. A seleção de cultivares foi baseada na associação com bactérias diazotróficas e na eficiência de absorção de nitrogênio das cultivares. Para o isolamento das bactérias, foram utilizados diferentes meios de enriquecimento semi-sólido e, após o isolamento, foram quantificadas a produção de AIA e a quantidade de N² fixada pelos isolados. A ocorrência de bactérias diazotróficas foi constatada em todas as cultivares avaliados sendo que a distribuição das bactérias isoladas foi influenciada pelo genótipo da planta. Todos os isolados foram aptos em fixar N² e produzir AIA in vitro.The present study aimed to evaluate the occurrence of diazotrophic bacterial associated with sorghum plants, to select efficient sorghum cultivars associated with diazotrophic bacterial, as well as to identify isolates efficient on nitrogen fixation (N² and indole acetic acid (IAA production. Fourteen forage sorghum cultivars were cropped in jars under two levels of nitrogen fertilization: 0 and 130kg ha-1 of N. The selection of sorghum cultivars was based on the association with diazothophic bacterial and on the efficiency of nitrogen absorption. Semi-solid enrichment medium was used for the isolation of the diazotrophic bacterial. The occurrence of diazotrophics was verified in all cultivars of sorghum evaluated and, the distribution of the isolates was affected by the plant genotype. All the isolates were able to fix N² and to produce IAA in vitro.

  5. Growth Kinetics of Diazotrophic Bacillus sphaericus UPMB10 Cultured Using Different Types and Concentrations of Carbon and Nitrogen Sources

    Directory of Open Access Journals (Sweden)

    Ooi, T. C.

    2008-01-01

    Full Text Available Growth kinetics of newly isolated diazotrophic Bacillus sphaericus UPMB10 grown in various carbon (lactate, acetate, glycerol, malate, fructose, xylose and sucrose and nitrogen (glutamate, yeast extract, arginine, hystadine, glycine, polypeptone, tryptophan, lysine, NH4Cl and urea sources was investigated using 2 L stirred tank fermenter. The highest growth was obtained in a medium containing lactate as a carbon source, which gave the highest maximum cell concentration of 2.30 g/L, which is corresponding to maximum viable cell count of 4.60 x 10^9 cfu/mL. However, the highest cell yield (1.06 g cell/g carbon consumed was obtained in cultivation using glycerol though slightly lower maximum viable cell count was obtained (3.22 x 10^9 cfu/mL. In addition, cost for the production of live cell using glycerol was about 15 times lower than the cost using lactate. Growth performance of this bacterium when yeast extract was used as a nitrogen source was comparable to the use of pure amino acid. The medium containing 1.8 g/L glycerol and 2 g/L yeast extract was suggested as optimal for growth of this bacterium, which gave carbon to nitrogen ratio (C/N of 10:1. The maximum viable cell count obtained in cultivation using optimised medium in 2 L stirred tank fermenter was 3.34 x 10^9 cfu/mL and the cells maintained its capacity for N2 fixation at 18 nmol C2H2/h.mL.

  6. Halotolerant Cyanobacterium Aphanothece halophytica Contains a Betaine Transporter Active at Alkaline pH and High Salinity

    OpenAIRE

    2006-01-01

    Aphanothece halophytica is a halotolerant alkaliphilic cyanobacterium which can grow in media of up to 3.0 M NaCl and pH 11. This cyanobacterium can synthesize betaine from glycine by three-step methylation using S-adenosylmethionine as a methyl donor. To unveil the mechanism of betaine uptake and efflux in this alkaliphile, we isolated and characterized a betaine transporter. A gene encoding a protein (BetTA. halophytica) that belongs to the betaine-choline-carnitine transporter (BCCT) famil...

  7. Backbone dynamics of reduced plastocyanin from the cyanobacterium Anabaena variabilis: Regions involved in electron transfer have enhanced mobility

    DEFF Research Database (Denmark)

    Ma, L.X.; Hass, M.A.S.; Vierick, N.;

    2003-01-01

    The dynamics of the backbone of the electron-transfer protein plastocyanin from the cyanobacterium Anabaena variabilis were determined from the N-15 and C-13(alpha) R-1 and R-2) relaxation rates and steady-state [H-1]-N-15 and [H-1]-C-13 nuclear Overhauser effects (NOEs) using the model-free appr......The dynamics of the backbone of the electron-transfer protein plastocyanin from the cyanobacterium Anabaena variabilis were determined from the N-15 and C-13(alpha) R-1 and R-2) relaxation rates and steady-state [H-1]-N-15 and [H-1]-C-13 nuclear Overhauser effects (NOEs) using the model...

  8. Interactions between diazotrophic bacteria and mycorrhizal fungus in maize genotypes Interações entre bactérias diazotróficas e fungo micorrízico em genótipos de milho

    Directory of Open Access Journals (Sweden)

    Marina Yumi Horta Miyauchi

    2008-01-01

    Full Text Available Some diazotrophic bacteria can fix nitrogen biologically in gramineous host plants. Generally, gramineous plants are also associated with mycorrhizal fungi, that can improve mainly plant P uptake. Among the factors affecting plant-microbe interactions, the plant genotype plays an important role. This study evaluates the effect of diazotrophic bacteria and an arbuscular mycorrhizal fungus (AMF, on five genotypes of maize (Zea mays L., in relation to plant biomass, shoot N and P concentrations, and fine root morphological traits. The experimental design was entirely randomized in a factorial 5 × 4 × 2 arrangement, i.e., five maize genotypes (hybrids C333B, AS3466, and PREMIUM, and the inbreed lines lg40897-1 and lg40505-1, three diazotrophic bacteria (Azospirillum lipoferum, A. amazonense, and Burkholderia sp. in addition to a control without bacterial inoculation, co-inoculated or not with the AMF Glomus clarum. The non-mycorrhizal plants inoculated with Azospirillum exhibited the highest N concentrations. The lines lg40897-1 and lg40505-1 showed higher P concentrations as compared to the hybrids, mainly when colonized by AMF. The higher levels of mycorrhizal colonization (90% occurred in the C333B and lg40897-1 genotypes, which also exhibited a greater root diameter. Mycorrhiza increased shoot and root biomass, besides root traits as total length, specific length, total surface, and incidence of root hairs in all genotypes. In addition, mycorrhiza also stimulated the root colonization by diazotrophic bacteria. The bacteria did not affect root morphological traits and mycorrhizal colonization.Algumas bactérias diazotróficas podem fixar N biologicamente em gramíneas, as quais se associam a fungos micorrízicos, o que pode levar a um aumento principalmente da absorção de P. Dentre os fatores que afetam as interações planta-microrganismos, o genótipo da planta tem importante papel. Esse trabalho avalia o efeito de bactérias diazotr

  9. First Evidence of Palytoxin and 42-Hydroxy-palytoxin in the Marine Cyanobacterium Trichodesmium

    Directory of Open Access Journals (Sweden)

    Dominique Laurent

    2011-03-01

    Full Text Available Marine pelagic diazotrophic cyanobacteria of the genus Trichodesmium (Oscillatoriales are widespread throughout the tropics and subtropics, and are particularly common in the waters of New Caledonia. Blooms of Trichodesmium are suspected to be a potential source of toxins in the ciguatera food chain and were previously reported to contain several types of paralyzing toxins. The toxicity of water-soluble extracts of Trichodesmium spp. were analyzed by mouse bioassay and Neuroblastoma assay and their toxic compounds characterized using liquid chromatography coupled with tandem mass spectrometry techniques. Here, we report the first identification of palytoxin and one of its derivatives, 42-hydroxy-palytoxin, in field samples of Trichodesmium collected in the New Caledonian lagoon. The possible role played by Trichodesmium blooms in the development of clupeotoxism, this human intoxication following the ingestion of plankton-eating fish and classically associated with Ostreopsis blooms, is also discussed.

  10. Genome erosion in a nitrogen-fixing vertically transmitted endosymbiotic multicellular cyanobacterium.

    Directory of Open Access Journals (Sweden)

    Liang Ran

    Full Text Available BACKGROUND: An ancient cyanobacterial incorporation into a eukaryotic organism led to the evolution of plastids (chloroplasts and subsequently to the origin of the plant kingdom. The underlying mechanism and the identities of the partners in this monophyletic event remain elusive. METHODOLOGY/PRINCIPAL FINDINGS: To shed light on this evolutionary process, we sequenced the genome of a cyanobacterium residing extracellularly in an endosymbiosis with a plant, the water-fern Azolla filiculoides Lam. This symbiosis was selected as it has characters which make it unique among extant cyanobacterial plant symbioses: the cyanobacterium lacks autonomous growth and is vertically transmitted between plant generations. Our results reveal features of evolutionary significance. The genome is in an eroding state, evidenced by a large proportion of pseudogenes (31.2% and a high frequency of transposable elements (approximately 600 scattered throughout the genome. Pseudogenization is found in genes such as the replication initiator dnaA and DNA repair genes, considered essential to free-living cyanobacteria. For some functional categories of genes pseudogenes are more prevalent than functional genes. Loss of function is apparent even within the 'core' gene categories of bacteria, such as genes involved in glycolysis and nutrient uptake. In contrast, serving as a critical source of nitrogen for the host, genes related to metabolic processes such as cell differentiation and nitrogen-fixation are well preserved. CONCLUSIONS/SIGNIFICANCE: This is the first finding of genome degradation in a plant symbiont and phenotypically complex cyanobacterium and one of only a few extracellular endosymbionts described showing signs of reductive genome evolution. Our findings suggest an ongoing selective streamlining of this cyanobacterial genome which has resulted in an organism devoted to nitrogen fixation and devoid of autonomous growth. The cyanobacterial symbiont of Azolla

  11. New anabaenopeptins, potent carboxypeptidase-A inhibitors from the cyanobacterium Aphanizomenon flos-aquae.

    Science.gov (United States)

    Murakami, M; Suzuki, S; Itou, Y; Kodani, S; Ishida, K

    2000-09-01

    Anabaenopeptins I (1) and J (2), two new ureido bond-containing cyclic peptides, were isolated from the cultured cyanobacterium Aphanizomenon flos-aquae (NIES-81) as potent carboxypeptidase-A (CPA) inhibitors. The gross structures of 1 and 2 were established by spectroscopic analysis, including the 2D NMR techniques. The absolute configurations of 1 and 2 were determined by spectral and chemical methods. Anabaenopeptins I and J inhibited CPA with IC(50) values of 5.2 and 7.6 ng/mL, respectively.

  12. Deciphering the mechanisms against oxidative stress in developing and mature akinetes of the cyanobacterium Aphanizomenon ovalisporum.

    Science.gov (United States)

    Kaplan-Levy, Ruth N; Hadas, Ora; Sukenik, Assaf

    2015-07-01

    Cells of filamentous cyanobacteria of the orders Nostocales and Stigonematales can differentiate into dormant forms called akinetes. Akinetes play a key role in the survival, abundance and distribution of the species, contributing an inoculum for their perennial blooms. In the cyanobacterium Aphanizomenon ovalisporum, potassium deficiency triggers the formation of akinetes. Here we present experimental evidence for the production of reactive oxygen species (ROS) during akinete development in response to potassium deficiency. The function of ROS as a primer signal for akinete differentiation was negated. Nevertheless, akinetes acquired protective mechanisms against oxidative damage during their differentiation and maintained them as they matured, giving akinetes advantages enabling survival in harsh conditions.

  13. Microcystin congeners contribute to toxicity in the halophilic cyanobacterium Aphanothece halophytica

    Directory of Open Access Journals (Sweden)

    Vishwakarma Rashi

    2014-01-01

    Full Text Available Aphanothece halophytica is an extremely saline cyanobacterium. This study investigates the toxic nature of the organism and presents the first report of hepatotoxic cyclic heptapeptide microcystin analogs. The activity of the crude extract was investigated in mice. Results showed acute toxicity with mice death at about 4 h. Histopathological examination indicated massive alveolar hemorrhage and extensive congestion in liver cells. Increases in the levels of serum enzymes, i.e., AST (aspartate aminotransferase, ALT (alanine aminotransferase and LDH (lactate dehydrogenase, provide further evidence of cell injury. An ELISA-based immunological detection kit confirmed the presence of microcystin analogs.

  14. Acetylome analysis reveals the involvement of lysine acetylation in photosynthesis and carbon metabolism in the model cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Mo, Ran; Yang, Mingkun; Chen, Zhuo; Cheng, Zhongyi; Yi, Xingling; Li, Chongyang; He, Chenliu; Xiong, Qian; Chen, Hui; Wang, Qiang; Ge, Feng

    2015-02-06

    Cyanobacteria are the oldest known life form inhabiting Earth and the only prokaryotes capable of performing oxygenic photosynthesis. Synechocystis sp. PCC 6803 (Synechocystis) is a model cyanobacterium used extensively in research on photosynthesis and environmental adaptation. Posttranslational protein modification by lysine acetylation plays a critical regulatory role in both eukaryotes and prokaryotes; however, its extent and function in cyanobacteria remain unexplored. Herein, we performed a global acetylome analysis on Synechocystis through peptide prefractionation, antibody enrichment, and high accuracy LC-MS/MS analysis; identified 776 acetylation sites on 513 acetylated proteins; and functionally categorized them into an interaction map showing their involvement in various biological processes. Consistent with previous reports, a large fraction of the acetylation sites are present on proteins involved in cellular metabolism. Interestingly, for the first time, many proteins involved in photosynthesis, including the subunits of phycocyanin (CpcA, CpcB, CpcC, and CpcG) and allophycocyanin (ApcA, ApcB, ApcD, ApcE, and ApcF), were found to be lysine acetylated, suggesting that lysine acetylation may play regulatory roles in the photosynthesis process. Six identified acetylated proteins associated with photosynthesis and carbon metabolism were further validated by immunoprecipitation and Western blotting. Our data provide the first global survey of lysine acetylation in cyanobacteria and reveal previously unappreciated roles of lysine acetylation in the regulation of photosynthesis. The provided data set may serve as an important resource for the functional analysis of lysine acetylation in cyanobacteria and facilitate the elucidation of the entire metabolic networks and photosynthesis process in this model cyanobacterium.

  15. Nice to meet you: genetic, epigenetic and metabolic controls of plant perception of beneficial associative and endophytic diazotrophic bacteria in non-leguminous plants.

    Science.gov (United States)

    Carvalho, T L G; Ballesteros, H G F; Thiebaut, F; Ferreira, P C G; Hemerly, A S

    2016-04-01

    A wide range of rhizosphere diazotrophic bacteria are able to establish beneficial associations with plants, being able to associate to root surfaces or even endophytically colonize plant tissues. In common, both associative and endophytic types of colonization can result in beneficial outcomes to the plant leading to plant growth promotion, as well as increase in tolerance against biotic and abiotic stresses. An intriguing question in such associations is how plant cell surface perceives signals from other living organisms, thus sorting pathogens from beneficial ones, to transduce this information and activate proper responses that will finally culminate in plant adaptations to optimize their growth rates. This review focuses on the recent advances in the understanding of genetic and epigenetic controls of plant-bacteria signaling and recognition during beneficial associations with associative and endophytic diazotrophic bacteria. Finally, we propose that "soil-rhizosphere-rhizoplane-endophytes-plant" could be considered as a single coordinated unit with dynamic components that integrate the plant with the environment to generate adaptive responses in plants to improve growth. The homeostasis of the whole system should recruit different levels of regulation, and recognition between the parties in a given environment might be one of the crucial factors coordinating these adaptive plant responses.

  16. Comparative genomics reveals diversified CRISPR-Cas systems of globally distributed Microcystis aeruginosa, a freshwater bloom-forming cyanobacterium

    Directory of Open Access Journals (Sweden)

    Chen eYang

    2015-05-01

    Full Text Available Microcystis aeruginosa is one of the most common and dominant bloom-forming cyanobacteria in freshwater lakes around the world. Microcystis cells can produce toxic secondary metabolites, such as microcystins, which are harmful to human health. Two M. aeruginosa strains were isolated from two highly eutrophic lakes in China and their genomes were sequenced. Comparative genomic analysis was performed with the 12 other available M. aeruginosa genomes and closely related unicellular cyanobacterium. Each genome of M. aeruginosa containing at least one clustered regularly interspaced short palindromic repeat (CRISPR locus and total 71 loci were identified, suggesting it is ubiquitous in M. aeruginosa genomes. In addition to the previously reported subtype I-D cas gene sets, three CAS subtypes I-A, III-A and III-B were identified and characterized in this study. Seven types of CRISPR direct repeat have close association with CAS subtype, confirming that different and specific secondary structures of CRISPR repeats are important for the recognition, binding and process of corresponding cas gene sets. Homology search of the CRISPR spacer sequences provides a history of not only resistance to bacteriophages and plasmids known to be associated with M. aeruginosa, but also the ability to target much more exogenous genetic material in the natural environment. These adaptive and heritable defense mechanisms play a vital role in keeping genomic stability and self-maintenance by restriction of horizontal gene transfer. Maintaining genomic stability and modulating genomic plasticity are both important evolutionary strategies for M. aeruginosa in adaptation and survival in various habitats.

  17. Comparative genomics reveals diversified CRISPR-Cas systems of globally distributed Microcystis aeruginosa, a freshwater bloom-forming cyanobacterium.

    Science.gov (United States)

    Yang, Chen; Lin, Feibi; Li, Qi; Li, Tao; Zhao, Jindong

    2015-01-01

    Microcystis aeruginosa is one of the most common and dominant bloom-forming cyanobacteria in freshwater lakes around the world. Microcystis cells can produce toxic secondary metabolites, such as microcystins, which are harmful to human health. Two M. aeruginosa strains were isolated from two highly eutrophic lakes in China and their genomes were sequenced. Comparative genomic analysis was performed with the 12 other available M. aeruginosa genomes and closely related unicellular cyanobacterium. Each genome of M. aeruginosa containing at least one clustered regularly interspaced short palindromic repeat (CRISPR) locus and total 71 loci were identified, suggesting it is ubiquitous in M. aeruginosa genomes. In addition to the previously reported subtype I-D cas gene sets, three CAS subtypes I-A, III-A and III-B were identified and characterized in this study. Seven types of CRISPR direct repeat have close association with CAS subtype, confirming that different and specific secondary structures of CRISPR repeats are important for the recognition, binding and process of corresponding cas gene sets. Homology search of the CRISPR spacer sequences provides a history of not only resistance to bacteriophages and plasmids known to be associated with M. aeruginosa, but also the ability to target much more exogenous genetic material in the natural environment. These adaptive and heritable defense mechanisms play a vital role in keeping genomic stability and self-maintenance by restriction of horizontal gene transfer. Maintaining genomic stability and modulating genomic plasticity are both important evolutionary strategies for M. aeruginosa in adaptation and survival in various habitats.

  18. Denitrifying and diazotrophic community responses to artificial warming in permafrost and tallgrass prairie soils

    OpenAIRE

    Christopher Ryan Penton; Derek eSt. Louis; Amanda ePham; James R Cole; Liyou eWu; Yiqi eLuo; E.A.G. eSchuur; Jizhong eZhou; Tiedje, James M.

    2015-01-01

    Increasing temperatures have been shown to impact soil biogeochemical processes, although the corresponding changes to the underlying microbial functional communities are not well understood. Alterations in the nitrogen (N) cycling functional component are particularly important as N availability can affect microbial decomposition rates of soil organic matter and influence plant productivity. To assess changes in the microbial component responsible for these changes, the composition of the N-...

  19. Unique Thylakoid Membrane Architecture of a Unicellular N2-Fixing Cyanobacterium Revealed by Electron Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Liberton, Michelle L.; Austin, Jotham R.; Berg, R. H.; Pakrasi, Himadri B.

    2011-04-01

    Cyanobacteria, descendants of the endosymbiont that gave rise to modern-day chloroplasts, are vital contributors to global biological energy conversion processes. A thorough understanding of the physiology of cyanobacteria requires detailed knowledge of these organisms at the level of cellular architecture and organization. In these prokaryotes, the large membrane protein complexes of the photosynthetic and respiratory electron transport chains function in the intracellular thylakoid membranes. Like plants, the architecture of the thylakoid membranes in cyanobacteria has direct impact on cellular bioenergetics, protein transport, and molecular trafficking. However, whole-cell thylakoid organization in cyanobacteria is not well understood. Here we present, by using electron tomography, an in-depth analysis of the architecture of the thylakoid membranes in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142. Based on the results of three-dimensional tomographic reconstructions of near-entire cells, we determined that the thylakoids in Cyanothece 51142 form a dense and complex network that extends throughout the entire cell. This thylakoid membrane network is formed from the branching and splitting of membranes and encloses a single lumenal space. The entire thylakoid network spirals as a peripheral ring of membranes around the cell, an organization that has not previously been described in a cyanobacterium. Within the thylakoid membrane network are areas of quasi-helical arrangement with similarities to the thylakoid membrane system in chloroplasts. This cyanobacterial thylakoid arrangement is an efficient means of packing a large volume of membranes in the cell while optimizing intracellular transport and trafficking.

  20. Unique thylakoid membrane architecture of a unicellular N2-fixing cyanobacterium revealed by electron tomography

    Energy Technology Data Exchange (ETDEWEB)

    Liberton, Michelle; Austin II, Jotham R; Berg, R. Howard; Pakrasi, Himadri B

    2011-04-01

    Cyanobacteria, descendants of the endosymbiont that gave rise to modern-day chloroplasts, are vital contributors to global biological energy conversion processes. A thorough understanding of the physiology of cyanobacteria requires detailed knowledge of these organisms at the level of cellular architecture and organization. In these prokaryotes, the large membrane protein complexes of the photosynthetic and respiratory electron transport chains function in the intracellular thylakoid membranes. Like plants, the architecture of the thylakoid membranes in cyanobacteria has direct impact on cellular bioenergetics, protein transport, and molecular trafficking. However, whole-cell thylakoid organization in cyanobacteria is not well understood. Here we present, by using electron tomography, an in-depth analysis of the architecture of the thylakoid membranes in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142. Based on the results of three-dimensional tomographic reconstructions of near-entire cells, we determined that the thylakoids in Cyanothece 51142 form a dense and complex network that extends throughout the entire cell. This thylakoid membrane network is formed from the branching and splitting of membranes and encloses a single lumenal space. The entire thylakoid network spirals as a peripheral ring of membranes around the cell, an organization that has not previously been described in a cyanobacterium. Within the thylakoid membrane network are areas of quasi-helical arrangement with similarities to the thylakoid membrane system in chloroplasts. This cyanobacterial thylakoid arrangement is an efficient means of packing a large volume of membranes in the cell while optimizing intracellular transport and trafficking.

  1. A Nostoc punctiforme sugar transporter necessary to establish a Cyanobacterium-plant symbiosis.

    Science.gov (United States)

    Ekman, Martin; Picossi, Silvia; Campbell, Elsie L; Meeks, John C; Flores, Enrique

    2013-04-01

    In cyanobacteria-plant symbioses, the symbiotic nitrogen-fixing cyanobacterium has low photosynthetic activity and is supplemented by sugars provided by the plant partner. Which sugars and cyanobacterial sugar uptake mechanism(s) are involved in the symbiosis, however, is unknown. Mutants of the symbiotically competent, facultatively heterotrophic cyanobacterium Nostoc punctiforme were constructed bearing a neomycin resistance gene cassette replacing genes in a putative sugar transport gene cluster. Results of transport activity assays using (14)C-labeled fructose and glucose and tests of heterotrophic growth with these sugars enabled the identification of an ATP-binding cassette-type transporter for fructose (Frt), a major facilitator permease for glucose (GlcP), and a porin needed for the optimal uptake of both fructose and glucose. Analysis of green fluorescent protein fluorescence in strains of N. punctiforme bearing frt::gfp fusions showed high expression in vegetative cells and akinetes, variable expression in hormogonia, and no expression in heterocysts. The symbiotic efficiency of N. punctiforme sugar transport mutants was investigated by testing their ability to infect a nonvascular plant partner, the hornwort Anthoceros punctatus. Strains that were specifically unable to transport glucose did not infect the plant. These results imply a role for GlcP in establishing symbiosis under the conditions used in this work.

  2. Unique thylakoid membrane architecture of a unicellular N2-fixing cyanobacterium revealed by electron tomography.

    Science.gov (United States)

    Liberton, Michelle; Austin, Jotham R; Berg, R Howard; Pakrasi, Himadri B

    2011-04-01

    Cyanobacteria, descendants of the endosymbiont that gave rise to modern-day chloroplasts, are vital contributors to global biological energy conversion processes. A thorough understanding of the physiology of cyanobacteria requires detailed knowledge of these organisms at the level of cellular architecture and organization. In these prokaryotes, the large membrane protein complexes of the photosynthetic and respiratory electron transport chains function in the intracellular thylakoid membranes. Like plants, the architecture of the thylakoid membranes in cyanobacteria has direct impact on cellular bioenergetics, protein transport, and molecular trafficking. However, whole-cell thylakoid organization in cyanobacteria is not well understood. Here we present, by using electron tomography, an in-depth analysis of the architecture of the thylakoid membranes in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142. Based on the results of three-dimensional tomographic reconstructions of near-entire cells, we determined that the thylakoids in Cyanothece 51142 form a dense and complex network that extends throughout the entire cell. This thylakoid membrane network is formed from the branching and splitting of membranes and encloses a single lumenal space. The entire thylakoid network spirals as a peripheral ring of membranes around the cell, an organization that has not previously been described in a cyanobacterium. Within the thylakoid membrane network are areas of quasi-helical arrangement with similarities to the thylakoid membrane system in chloroplasts. This cyanobacterial thylakoid arrangement is an efficient means of packing a large volume of membranes in the cell while optimizing intracellular transport and trafficking.

  3. Novel thermostable glycosidases in the extracellular matrix of the terrestrial cyanobacterium Nostoc commune.

    Science.gov (United States)

    Morsy, Fatthy Mohamed; Kuzuha, Satomi; Takani, Yayoi; Sakamoto, Toshio

    2008-10-01

    The cyanobacterium Nostoc commune is adapted to the terrestrial environment and forms a visible colony in which the cells are embedded in extracellular polysaccharides (EPSs), which play a crucial role in the extreme desiccation tolerance of this organism. When natural colonies were immersed in water, degradation of the colonies occurred within 2 days and N. commune cells were released into the water. The activities that hydrolyze glycoside bonds in various N. commune fractions were examined using artificial nitrophenyl-linked sugars as substrates. A beta-D-glucosidase purified from the water-soluble fraction was resistant to 20 min of boiling. The beta-D-glucosidase, with a molecular mass of 20 kDa, was identified as a cyanobacterial fasciclin protein based on its N-terminal amino-acid sequence. The 36-kDa major protein in the water-soluble fraction was purified, and the N-terminal amino-acid sequence of the protein was found to be identical to that of the water-stress protein (WspA) of N. commune. This WspA protein also showed heat-resistant beta-D-galactosidase activity. The fasciclin protein and WspA in the extracellular matrix may play a role in the hydrolysis of the EPSs surrounding the cells, possibly as an aid in the dispersal of cells, thus expanding the colonies of this cyanobacterium.

  4. Crucial Role of Extracellular Polysaccharides in Desiccation and Freezing Tolerance in the Terrestrial Cyanobacterium Nostoc commune

    Science.gov (United States)

    Tamaru, Yoshiyuki; Takani, Yayoi; Yoshida, Takayuki; Sakamoto, Toshio

    2005-01-01

    The cyanobacterium Nostoc commune is adapted to the terrestrial environment and has a cosmopolitan distribution. In this study, the role of extracellular polysaccharides (EPS) in the desiccation tolerance of photosynthesis in N. commune was examined. Although photosynthetic O2 evolution was not detected in desiccated colonies, the ability of the cells to evolve O2 rapidly recovered after rehydration. The air-dried colonies contained approximately 10% (wt/wt) water, and field-isolated, natural colonies with EPS were highly water absorbent and were rapidly hydrated by atmospheric moisture. The cells embedded in EPS in Nostoc colonies were highly desiccation tolerant, and O2 evolution was not damaged by air drying. Although N. commune was determined to be a mesophilic cyanobacterium, the cells with EPS were heat tolerant in a desiccated state. EPS could be removed from cells by homogenizing colonies with a blender and filtering with coarse filter paper. This treatment to remove EPS did not damage Nostoc cells or their ability to evolve O2, but O2 evolution was significantly damaged by desiccation treatment of the EPS-depleted cells. Similar to the EPS-depleted cells, the laboratory culture strain KU002 had only small amount of EPS and was highly sensitive to desiccation. In the EPS-depleted cells, O2 evolution was also sensitive to freeze-thaw treatment. These results strongly suggest that EPS of N. commune is crucial for the stress tolerance of photosynthesis during desiccation and during freezing and thawing. PMID:16269775

  5. Bouillonamide: A Mixed Polyketide–Peptide Cytotoxin from the Marine Cyanobacterium Moorea bouillonii

    Directory of Open Access Journals (Sweden)

    Lik Tong Tan

    2013-08-01

    Full Text Available The tropical marine cyanobacterium, Moorea bouillonii, has gained recent attention as a rich source of bioactive natural products. Continued chemical investigation of this cyanobacterium, collected from New Britain, Papua New Guinea, yielded a novel cytotoxic cyclic depsipeptide, bouillonamide (1, along with previously reported molecules, ulongamide A and apratoxin A. Planar structure of bouillonamide was established by extensive 1D and 2D NMR experiments, including multi-edited HSQC, TOCSY, HBMC, and ROESY experiments. In addition to the presence of α-amino acid residues, compound 1 contained two unique polyketide-derived moieties, namely a 2-methyl-6-methylamino-hex-5-enoic acid (Mmaha residue and a unit of 3-methyl-5-hydroxy-heptanoic acid (Mhha. Absolute stereochemistry of the α-amino acid units in bouillonamide was determined mainly by Marfey’s analysis. Compound 1 exhibited mild toxicity with IC50’s of 6.0 µM against the neuron 2a mouse neuroblastoma cells.

  6. Dynamics of the Toxin Cylindrospermopsin and the Cyanobacterium Chrysosporum (Aphanizomenon ovalisporum in a Mediterranean Eutrophic Reservoir

    Directory of Open Access Journals (Sweden)

    Ali Fadel

    2014-10-01

    Full Text Available Chrysosporum ovalisporum is a cylindrospermopsin toxin producing cyanobacterium that was reported in several lakes and reservoirs. Its growth dynamics and toxin distribution in field remain largely undocumented. Chrysosporum ovalisporum was reported in 2009 in Karaoun Reservoir, Lebanon. We investigated the factors controlling the occurrence of this cyanobacterium and vertical distribution of cylindrospermopsin in Karaoun Reservoir. We conducted bi-weekly sampling campaigns between May 2012 and August 2013. Results showed that Chrysosporum ovalisporum is an ecologically plastic species that was observed in all seasons. Unlike the high temperatures, above 26 °C, which is associated with blooms of Chrysosporum ovalisporum in Lakes Kinneret (Israel, Lisimachia and Trichonis (Greece and Arcos Reservoir (Spain, Chrysosporum ovalisporum in Karaoun Reservoir bloomed in October 2012 at a water temperature of 22 °C during weak stratification. Cylindrospermopsin was detected in almost all water samples even when Chrysosporum ovalisporum was not detected. Chrysosporum ovalisporum biovolumes and cylindrospermopsin concentrations were not correlated (n = 31, r2 = −0.05. Cylindrospermopsin reached a maximum concentration of 1.7 µg L−1. The vertical profiles of toxin concentrations suggested its possible degradation or sedimentation resulting in its disappearance from the water column. The field growth conditions of Chrysosporum ovalisporum in this study revealed that it can bloom at the subsurface water temperature of 22 °C increasing the risk of its development and expansion in lakes located in temperate climate regions.

  7. A stable, reusable, and highly active photosynthetic bioreactor by bio-interfacing an individual cyanobacterium with a mesoporous bilayer nanoshell.

    Science.gov (United States)

    Jiang, Nan; Yang, Xiao-Yu; Deng, Zhao; Wang, Li; Hu, Zhi-Yi; Tian, Ge; Ying, Guo-Liang; Shen, Ling; Zhang, Ming-Xi; Su, Bao-Lian

    2015-05-06

    An individual cyanobacterium cell is interfaced with a nanoporous biohybrid layer within a mesoporous silica layer. The bio-interface acts as an egg membrane for cell protection and growth of outer shell. The resulting bilayer shell provides efficient functions to create a single cell photosynthetic bioreactor with high stability, reusability, and activity.

  8. Diurnal expression of hetR and diazocyte development in the filamentous non-heterocystous cyanobacterium Trichodesmium erythraeum

    NARCIS (Netherlands)

    El-Shehawy, R.; Lugomela, C.; Ernst, A.; Bergman, B.

    2003-01-01

    The marine non-heterocystous cyanobacterium Trichodesmium fixes atmospheric N2 aerobically in light. In situ immunolocalization/light microscopy of NifH revealed that lighter, non-granulated cell regions observed correspond to the nitrogenase-containing diazocyte clusters in Trichodesmium IMS101. Th

  9. A comparison of fermentation in the cyanobacterium Microcystis PCC7806 grown under a light/dark cycle and continuous light

    NARCIS (Netherlands)

    Moezelaar, R.; Stal, L.J.

    1997-01-01

    The cyanobacterium Microcystis PCC7806, grown under continuous light, fermented endogenously stored glycogen to equimolar amounts of acetate and ethanol when incubated anaerobically in the dark. In addition, H-2, CO2 and some L-lactate were produced. This fermentation pattern differed from that disp

  10. Pulsed nitrogen supply induces dynamic changes in the amino acid compositionand microcystin production of the harmful cyanobacterium Planktothrix agardhii

    NARCIS (Netherlands)

    Van de Waal, D.B.; Ferreruela, G.; Tonk, L.; Van Donk, E.; Huisman, J.; Visser, P.M.; Matthijs, H.C.P.

    2010-01-01

    Planktothrix agardhii is a widespread harmful cyanobacterium of eutrophic waters, and can produce the hepatotoxins [Asp3]microcystin-LR and [Asp3]microcystin-RR. These two microcystin variants differ in their first variable amino acid position, which is occupied by either leucine (L) or arginine (R)

  11. Pulsed nitrogen supply induces dynamic changes in the amino acid composition and microcystin production of the harmful cyanobacterium Planktothrix agardhii

    NARCIS (Netherlands)

    van de Waal, D.B.; Ferreruela, G.; Tonk, L.; van Donk, E.; Huisman, J.; Visser, P.M.; Matthijs, H.C.P.

    2010-01-01

    Planktothrix agardhii is a widespread harmful cyanobacterium of eutrophic waters, and can produce the hepatotoxins [Asp3]microcystin-LR and [Asp3]microcystin-RR. These two microcystin variants differ in their first variable amino acid position, which is occupied by either leucine (L) or arginine (R)

  12. Effects of the cyanobacterium Cylindrospermopsis raciborskii on feeding and life-history characteristics of the grazer Daphnia magna

    NARCIS (Netherlands)

    Soares, M.C.S.; Lürling, M.F.L.L.W.; Panosso, R.; Huszar, V.M.

    2009-01-01

    Laboratory experiments were used to test the hypothesis that feeding and growth of the zooplankton grazer Daphnia magna will decrease with increasing proportions of the cyanobacterium Cylindrospermopsis raciborskii in the diet (mixed feeds with the green alga Scenedesmus obliquus). A strain of C.

  13. Cloning of a third nitrate reductase gene from the cyanobacterium Anacystis nidulans R2 using a shuttle cosmid library

    NARCIS (Netherlands)

    Kuhlemeier, C.J.; Teeuwsen, V.J.P.; Janssen, M.J.T.; Arkel, G.A. van

    1984-01-01

    A strategy for gene cloning in the cyanobacterium Anacystis nidulans R2 was developed which made use of a gene library constructed in a shuttle cosmid vector. The method involved phenotypic complementation of mutants with pooled cosmid DNA. The development of the procedure and its application to the

  14. Gas exchange in the filamentous cyanobacterium Nostoc punctiforme strain ATCC 29133 and Its hydrogenase-deficient mutant strain NHM5.

    Science.gov (United States)

    Lindberg, Pia; Lindblad, Peter; Cournac, Laurent

    2004-04-01

    Nostoc punctiforme ATCC 29133 is a nitrogen-fixing, heterocystous cyanobacterium of symbiotic origin. During nitrogen fixation, it produces molecular hydrogen (H(2)), which is recaptured by an uptake hydrogenase. Gas exchange in cultures of N. punctiforme ATCC 29133 and its hydrogenase-free mutant strain NHM5 was studied. Exchange of O(2), CO(2), N(2), and H(2) was followed simultaneously with a mass spectrometer in cultures grown under nitrogen-fixing conditions. Isotopic tracing was used to separate evolution and uptake of CO(2) and O(2). The amount of H(2) produced per molecule of N(2) fixed was found to vary with light conditions, high light giving a greater increase in H(2) production than N(2) fixation. The ratio under low light and high light was approximately 1.4 and 6.1 molecules of H(2) produced per molecule of N(2) fixed, respectively. Incubation under high light for a longer time, until the culture was depleted of CO(2), caused a decrease in the nitrogen fixation rate. At the same time, hydrogen production in the hydrogenase-deficient strain was increased from an initial rate of approximately 6 micro mol (mg of chlorophyll a)(-1) h(-1) to 9 micro mol (mg of chlorophyll a)(-1) h(-1) after about 50 min. A light-stimulated hydrogen-deuterium exchange activity stemming from the nitrogenase was observed in the two strains. The present findings are important for understanding this nitrogenase-based system, aiming at photobiological hydrogen production, as we have identified the conditions under which the energy flow through the nitrogenase can be directed towards hydrogen production rather than nitrogen fixation.

  15. Salinity tolerance of Picochlorum atomus and the use of salinity for contamination control by the freshwater cyanobacterium Pseudanabaena limnetica.

    Directory of Open Access Journals (Sweden)

    Nicolas von Alvensleben

    Full Text Available Microalgae are ideal candidates for waste-gas and -water remediation. However, salinity often varies between different sites. A cosmopolitan microalga with large salinity tolerance and consistent biochemical profiles would be ideal for standardised cultivation across various remediation sites. The aims of this study were to determine the effects of salinity on Picochlorum atomus growth, biomass productivity, nutrient uptake and biochemical profiles. To determine if target end-products could be manipulated, the effects of 4-day nutrient limitation were also determined. Culture salinity had no effect on growth, biomass productivity, phosphate, nitrate and total nitrogen uptake at 2, 8, 18, 28 and 36 ppt. 11 ppt, however, initiated a significantly higher total nitrogen uptake. While salinity had only minor effects on biochemical composition, nutrient depletion was a major driver for changes in biomass quality, leading to significant increases in total lipid, fatty acid and carbohydrate quantities. Fatty acid composition was also significantly affected by nutrient depletion, with an increased proportion of saturated and mono-unsaturated fatty acids. Having established that P. atomus is a euryhaline microalga, the effects of culture salinity on the development of the freshwater cyanobacterial contaminant Pseudanabaena limnetica were determined. Salinity at 28 and 36 ppt significantly inhibited establishment of P. limnetica in P. atomus cultures. In conclusion, P. atomus can be deployed for bioremediation at sites with highly variable salinities without effects on end-product potential. Nutrient status critically affected biochemical profiles--an important consideration for end-product development by microalgal industries. 28 and 36 ppt slow the establishment of the freshwater cyanobacterium P. limnetica, allowing for harvest of low contaminant containing biomass.

  16. Proteomic approaches to identify substrates of the three Deg/HtrA proteases of the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Tam, Lam X; Aigner, Harald; Timmerman, Evy; Gevaert, Kris; Funk, Christiane

    2015-06-15

    The family of Deg/HtrA proteases plays an important role in quality control of cellular proteins in a wide range of organisms. In the genome of the cyanobacterium Synechocystis sp. PCC 6803, a model organism for photosynthetic research and renewable energy products, three Deg proteases are encoded, termed HhoA, HhoB and HtrA. In the present study, we compared wild-type (WT) Synechocystis cells with the single insertion mutants ΔhhoA, ΔhhoB and ΔhtrA. Protein expression of the remaining Deg/HtrA proteases was strongly affected in the single insertion mutants. Detailed proteomic studies using DIGE (difference gel electrophoresis) and N-terminal COFRADIC (N-terminal combined fractional diagonal chromatography) revealed that inactivation of a single Deg protease has similar impact on the proteomes of the three mutants; differences to WT were observed in enzymes involved in the major metabolic pathways. Changes in the amount of phosphate permease system Pst-1 were observed only in the insertion mutant ΔhhoB. N-terminal COFRADIC analyses on cell lysates of ΔhhoB confirmed changed amounts of many cell envelope proteins, including the phosphate permease systems, compared with WT. In vitro COFRADIC studies were performed to identify the specificity profiles of the recombinant proteases rHhoA, rHhoB or rHtrA added to the Synechocystis WT proteome. The combined in vivo and in vitro N-terminal COFRADIC datasets propose RbcS as a natural substrate for HhoA, PsbO for HhoB and HtrA and Pbp8 for HtrA. We therefore suggest that each Synechocystis Deg protease protects the cell through different, but connected mechanisms. © The Authors Journal compilation © 2015 Biochemical Society.

  17. Integrative analysis of large scale expression profiles reveals core transcriptional response and coordination between multiple cellular processes in a cyanobacterium

    Directory of Open Access Journals (Sweden)

    Bhattacharyya-Pakrasi Maitrayee

    2010-08-01

    Full Text Available Abstract Background Cyanobacteria are the only known prokaryotes capable of oxygenic photosynthesis. They play significant roles in global biogeochemical cycles and carbon sequestration, and have recently been recognized as potential vehicles for production of renewable biofuels. Synechocystis sp. PCC 6803 has been extensively used as a model organism for cyanobacterial studies. DNA microarray studies in Synechocystis have shown varying degrees of transcriptome reprogramming under altered environmental conditions. However, it is not clear from published work how transcriptome reprogramming affects pre-existing networks of fine-tuned cellular processes. Results We have integrated 163 transcriptome data sets generated in response to numerous environmental and genetic perturbations in Synechocystis. Our analyses show that a large number of genes, defined as the core transcriptional response (CTR, are commonly regulated under most perturbations. The CTR contains nearly 12% of Synechocystis genes found on its chromosome. The majority of genes in the CTR are involved in photosynthesis, translation, energy metabolism and stress protection. Our results indicate that a large number of differentially regulated genes identified in most reported studies in Synechocystis under different perturbations are associated with the general stress response. We also find that a majority of genes in the CTR are coregulated with 25 regulatory genes. Some of these regulatory genes have been implicated in cellular responses to oxidative stress, suggesting that reactive oxygen species are involved in the regulation of the CTR. A Bayesian network, based on the regulation of various KEGG pathways determined from the expression patterns of their associated genes, has revealed new insights into the coordination between different cellular processes. Conclusion We provide here the first integrative analysis of transcriptome data sets generated in a cyanobacterium. This

  18. Denitrifying and diazotrophic community responses to artificial warming in permafrost and tallgrass prairie soils.

    Science.gov (United States)

    Penton, Christopher R; St Louis, Derek; Pham, Amanda; Cole, James R; Wu, Liyou; Luo, Yiqi; Schuur, E A G; Zhou, Jizhong; Tiedje, James M

    2015-01-01

    Increasing temperatures have been shown to impact soil biogeochemical processes, although the corresponding changes to the underlying microbial functional communities are not well understood. Alterations in the nitrogen (N) cycling functional component are particularly important as N availability can affect microbial decomposition rates of soil organic matter and influence plant productivity. To assess changes in the microbial component responsible for these changes, the composition of the N-fixing (nifH), and denitrifying (nirS, nirK, nosZ) soil microbial communities was assessed by targeted pyrosequencing of functional genes involved in N cycling in two major biomes where the experimental effect of climate warming is under investigation, a tallgrass prairie in Oklahoma (OK) and the active layer above permafrost in Alaska (AK). Raw reads were processed for quality, translated with frameshift correction, and a total of 313,842 amino acid sequences were clustered and linked to a nearest neighbor using reference datasets. The number of OTUs recovered ranged from 231 (NifH) to 862 (NirK). The N functional microbial communities of the prairie, which had experienced a decade of experimental warming were the most affected with changes in the richness and/or overall structure of NifH, NirS, NirK and NosZ. In contrast, the AK permafrost communities, which had experienced only 1 year of warming, showed decreased richness and a structural change only with the nirK-harboring bacterial community. A highly divergent nirK-harboring bacterial community was identified in the permafrost soils, suggesting much novelty, while other N functional communities exhibited similar relatedness to the reference databases, regardless of site. Prairie and permafrost soils also harbored highly divergent communities due mostly to differing major populations.

  19. Genetic transformation of marine cyanobacterium Synechococcus sp. CC9311 (Cyanophyceae) by electroporation

    Science.gov (United States)

    Chen, Huaxin; Lin, Hanzhi; Jiang, Peng; Li, Fuchao; Qin, Song

    2013-03-01

    Synechococcus sp. CC9311 is a marine cyanobacterium characterized by type IV chromatic acclimation (CA). A genetic transformation system was developed as a first step to elucidate the molecular mechanism of CA. The results show that Synechococcus sp. CC9311 cells were sensitive to four commonly used antibiotics: ampicillin, kanamycin, spectinomycin, and chloramphenicol. An integrative plasmid to disrupt the putative phycoerythrin lyase gene mpeV, using a kanamycin resistance gene as selectable marker, was constructed by recombinant polymerase chain reaction. The plasmid was then transformed into Synechococcus sp. CC9311 via electroporation. High transformation efficiency was achieved at a field strength of 2 kV/cm. DNA analysis showed that mpeV was fully disrupted following challenge of the transformants with a high concentration of kanamycin. In addition, the transformants that displayed poor growth on agar SN medium could be successfully plated on agarose SN medium.

  20. Genetically modified cyanobacterium Nostoc muscorum overproducing proline in response to salinity and osmotic stresses

    Indian Academy of Sciences (India)

    Santosh Bhargava

    2006-06-01

    In the parent Nostoc muscorum an active proline oxidase enzyme is required to assimilate exogenous proline as a fixed nitrogen source. Cyanobacterial mutants, resistant to growth inhibitory action of proline analogue L-azetidine-2-carboxylate (Ac-R), were deficient in proline oxidase activity, and were over-accumulators of proline. Proline over-accumulation, resulting either from mutational acquisition of the Ac-R phenotype, or from salinity-induced uptake of exogenous proline, confirmed enhanced salinity/osmotic tolerance in the mutant strain. The nitrogenase activity and photosynthetic O2 evolution of the parent were sensitive to both salinity as well as osmotic stresses than of Ac-R mutant strain. In addition, the mutation to Ac-resistant phenotype showed no alteration in salinity inducible potassium transport system in the cyanobacterium

  1. Bifunctional enzyme FBPase/SBPase is essential for photoautotrophic growth in cyanobacterium Synechocystis sp. PCC 6803

    Institute of Scientific and Technical Information of China (English)

    Chunlan Yan; Xudong Xu

    2008-01-01

    From a random insertion mutant library of Synechocystis sp. PCC 6803, a mutant defective in photoautotrophic growth was obtained. The interrupted gene was identified to be sir2094 (fbpl), which encodes the fructose-l,6-biphosphatase (FBPase)/sedoheptu-lose-1,7-biphosphatase (SBPase) bifunctional enzyme (F-I). Two other independently constructed slr2094 mutants showed an identical phenotype. The FBPase activity was found to be virtually lacking in an sir2094 mutant, which was sensitive to light under mixotrophic growth conditions. These results indicate that sir2094 is the only active FBPase-encoding gene in this cyanobacterium. Inactivation of photosystem 11 by interrupting psbB in sir2094 mutant alleviated the sensitiveness to light. This report provides the direct genetic evi-dence for the essential role of F-I in the photosynthesis of Synechocystis sp. PCC 6803.

  2. Cadmium-mediated resistance to metals and antibiotics in a cyanobacterium

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S.P.; Pandey, A.K.

    1982-01-01

    Cadmium-resistant strains of the cyanobacterium Nostoc calcicola were isolated through the step-wise transfer of the organism to higher levels of the metal. One of the Cd-resistant strains (CDsup(r)-10) showed cross-resistance to antibiotics like neomycin (1 ..mu..g/ml), chloramphenicol (3 ..mu..g/ml) but not to streptomycin. The Cd-resistant strain also tolerated elevated levels of metals such as zinc 20 ppm) and mercury (1 ppm). The stability of the metal-resistance required the presence of Cd/sup 2 +/ ions in the growth medium. It is suggested that metal resistance may also be determined by gene(s) on the antibiotic resistance plasmids in cyanobacteria.

  3. Sacrolide A, a new antimicrobial and cytotoxic oxylipin macrolide from the edible cyanobacterium Aphanothece sacrum

    Directory of Open Access Journals (Sweden)

    Naoya Oku

    2014-08-01

    Full Text Available Macroscopic gelatinous colonies of freshwater cyanobacterium Aphanothece sacrum, a luxury ingredient for Japanese cuisine, were found to contain a new oxylipin-derived macrolide, sacrolide A (1, as an antimicrobial component. The configuration of two chiral centers in 1 was determined by a combination of chiral anisotropy analysis and conformational analysis of different ring-opened derivatives. Compound 1 inhibited the growth of some species of Gram-positive bacteria, yeast Saccharomyces cerevisiae and fungus Penicillium chrysogenum, and was also cytotoxic to 3Y1 rat fibroblasts. Concern about potential food intoxication caused by accidental massive ingestion of A. sacrum was dispelled by the absence of 1 in commercial products. A manual procedure for degrading 1 in raw colonies was also developed, enabling a convenient on-site detoxification at restaurants or for personal consumption.

  4. Sacrolide A, a new antimicrobial and cytotoxic oxylipin macrolide from the edible cyanobacterium Aphanothece sacrum.

    Science.gov (United States)

    Oku, Naoya; Matsumoto, Miyako; Yonejima, Kohsuke; Tansei, Keijiroh; Igarashi, Yasuhiro

    2014-01-01

    Macroscopic gelatinous colonies of freshwater cyanobacterium Aphanothece sacrum, a luxury ingredient for Japanese cuisine, were found to contain a new oxylipin-derived macrolide, sacrolide A (1), as an antimicrobial component. The configuration of two chiral centers in 1 was determined by a combination of chiral anisotropy analysis and conformational analysis of different ring-opened derivatives. Compound 1 inhibited the growth of some species of Gram-positive bacteria, yeast Saccharomyces cerevisiae and fungus Penicillium chrysogenum, and was also cytotoxic to 3Y1 rat fibroblasts. Concern about potential food intoxication caused by accidental massive ingestion of A. sacrum was dispelled by the absence of 1 in commercial products. A manual procedure for degrading 1 in raw colonies was also developed, enabling a convenient on-site detoxification at restaurants or for personal consumption.

  5. Flocculation properties of several microalgae and a cyanobacterium species during ferric chloride, chitosan and alkaline flocculation.

    Science.gov (United States)

    Lama, Sanjaya; Muylaert, Koenraad; Karki, Tika Bahadur; Foubert, Imogen; Henderson, Rita K; Vandamme, Dries

    2016-11-01

    Flocculation holds great potential as a low-cost harvesting method for microalgae biomass production. Three flocculation methods (ferric chloride, chitosan, and alkaline flocculation) were compared in this study for the harvesting of 9 different freshwater and marine microalgae and one cyanobacterium species. Ferric chloride resulted in a separation efficiency greater than 90% with a concentration factor (CF) higher than 10 for all species. Chitosan flocculation worked generally very well for freshwater microalgae, but not for marine species. Alkaline flocculation was most efficient for harvesting of Nannochloropsis, Chlamydomonas and Chlorella sp. The concentration factor was highly variable between microalgae species. Generally, minimum flocculant dosages were highly variable across species, which shows that flocculation may be a good harvesting method for some species but not for others. This study shows that microalgae and cyanobacteria species should not be selected solely based on their productivity but also on their potential for low-cost separation.

  6. Genetic transformation of marine cyanobacterium Synechococcus sp.CC9311 (Cyanophyceae) by electroporation

    Institute of Scientific and Technical Information of China (English)

    CHEN Huaxin; LIN Hanzhi; JIANG Peng; LI Fuchao; QIN Song

    2013-01-01

    Synechococcus sp.CC9311 is a marine cyanobacterium characterized by type V chromatic acclimation (CA).A genetic transformation system was developed as a first step to elucidate the molecular mechanism of CA.The results show that Synechococcus sp.CC9311 cells were sensitive to four commonly used antibiotics:ampicillin,kanamycin,spectinomycin,and chloramphenicol.An integrative plasmid to disrupt the putative phycoerythrin lyase gene mpeV,using a kanamycin resistance gene as selectable marker,was constructed by recombinant polymerase chain reaction.The plasmid was then transformed into Synechococcus sp.CC9311 via electroporation.High transformation efficiency was achieved at a field strength of 2 kV/cm.DNA analysis showed that rpe V was fully disrupted following challenge of the transformants with a high concentration of kanamycin.In addition,the transformants that displayed poor growth on agar SN medium could be successfully plated on agarose SN medium.

  7. Space-environmental tolerances in a cyanobacterium, Nostoc sp. HK-01

    Science.gov (United States)

    Tomita-Yokotani, Kaori; Yokobori, Shin-ichi; Kimura, Shunta; Sato, Seigo; Katoh, Hiroshi; Ajioka, Reiko; Yamagishi, Akihiko; Inoue, Kotomi

    2016-07-01

    We have been investigating the tolerances to space-environments of a cyanobacterium, Nostoc sp. HK-01 (hereafter referred to as HK-01). Dry colonies of HK-01 had high tolerance to dry conditions, but more detailed information about tolerance to high-temperature, UV, gamma-ray and heavy particle beams were not deeply investigated. The obtained dry colonies of HK-01 after exposure to each of the conditions described above were investigated. In all of the tested colonies of HK-01 after exposure, all or some of the cells in the colonies were alive. One of the purposes of space agriculture is growing plants on Mars. In the early stages, of our research, cyanobacteria are introduced on Mars to promote the oxidation of the atmosphere and the formation of soil from Mars's regolith. HK-01 will contribute to each of these factors in the future.

  8. Phycobiliprotein accumulation in cyanobacterium Nostoc linckia and modification of antioxidant activity

    Directory of Open Access Journals (Sweden)

    Ana VALUTA

    2015-01-01

    Full Text Available The article deals with iron(III coordination compounds with Schiff bases as ligands and their impact on phycobiliprotein accumulation by cyanobacterium Nostoc linckia. Stimulatory effect depends on the applied dose and in case of three compounds, the concentration 20 mg/L was determined as one with moderate intensity. Lower concentrations resulted in an increase of the phycobiliprotein synthesis. There was found a significant positive correlation between phycobiliprotein content and ABTS (2.2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid assay values displayed by aqueous extracts from Nostoc linckia biomass cultivated in nutrient medium with these coordination compounds. Hence, it is possible to modify the antioxidant activity of Nostoc biomass by applying low concentrations of chemical stimuli.

  9. Composition and occurrence of lipid droplets in the cyanobacterium Nostoc punctiforme.

    Science.gov (United States)

    Peramuna, Anantha; Summers, Michael L

    2014-12-01

    Inclusions of neutral lipids termed lipid droplets (LDs) located throughout the cell were identified in the cyanobacterium Nostoc punctiforme by staining with lipophylic fluorescent dyes. LDs increased in number upon entry into stationary phase and addition of exogenous fructose indicating a role for carbon storage, whereas high-light stress did not increase LD numbers. LD accumulation increased when nitrate was used as the nitrogen source during exponential growth as compared to added ammonia or nitrogen-fixing conditions. Analysis of isolated LDs revealed enrichment of triacylglycerol (TAG), α-tocopherol, and C17 alkanes. LD TAG from exponential phase growth contained mainly saturated C16 and C18 fatty acids, whereas stationary phase LD TAG had additional unsaturated fatty acids characteristic of whole cells. This is the first characterization of cyanobacterial LD composition and conditions leading to their production. Based upon their abnormally large size and atypical location, these structures represent a novel sub-organelle in cyanobacteria.

  10. BMAA Inhibits Nitrogen Fixation in the Cyanobacterium Nostoc sp. PCC 7120

    Science.gov (United States)

    Berntzon, Lotta; Erasmie, Sven; Celepli, Narin; Eriksson, Johan; Rasmussen, Ulla; Bergman, Birgitta

    2013-01-01

    Cyanobacteria produce a range of secondary metabolites, one being the neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA), proposed to be a causative agent of human neurodegeneration. As for most cyanotoxins, the function of BMAA in cyanobacteria is unknown. Here, we examined the effects of BMAA on the physiology of the filamentous nitrogen-fixing cyanobacterium Nostoc sp. PCC 7120. Our data show that exogenously applied BMAA rapidly inhibits nitrogenase activity (acetylene reduction assay), even at micromolar concentrations, and that the inhibition was considerably more severe than that induced by combined nitrogen sources and most other amino acids. BMAA also caused growth arrest and massive cellular glycogen accumulation, as observed by electron microscopy. With nitrogen fixation being a process highly sensitive to oxygen species we propose that the BMAA effects found here may be related to the production of reactive oxygen species, as reported for other organisms. PMID:23966039

  11. Heterologous expression of an algal hydrogenase in a hetero-cystous cyanobacterium

    Energy Technology Data Exchange (ETDEWEB)

    Thorsten Heidorn; Peter Lindblad [Dept. of Physiological Botany, Uppsala University, V illavagen 6, SE-752 36 Uppsala, (Sweden)

    2006-07-01

    For the expression of an active algal [FeFe] hydrogenase in the hetero-cystous cyanobacterium Nostoc punctiforme A TCC 29133 the Chlamydomonas reinhardtii hydrogenase gene hydA1 and the accessory genes hydEF and hydG are to be introduced into the cyano-bacterial cells. The genes were amplified by PCR from EST clones, cloned into the cloning vector pBluescript SK+ and sequenced. An expression vector for multi-cistronic cloning, based on pSCR202, was constructed and for a functional test GFP was inserted as a reporter gene. The GFP construct was transformed into Nostoc punctiforme A TCC 29133 by electroporation and expression of GFP was visualized by fluorescence microscopy. (authors)

  12. Growth and biopigment accumulation of cyanobacterium Spirulina platensis at different light intensities and temperature

    Science.gov (United States)

    Kumar, Manoj; Kulshreshtha, Jyoti; Singh, Gajendra Pal

    2011-01-01

    In order to find out optimum culture condition for algal growth, the effect of light irradiance and temperature on growth rate, biomass composition and pigment production of Spirulina platensis were studied in axenic batch cultures. Growth kinetics of cultures showed a wide range of temperature tolerance from 20 °C to 40 °C. Maximum growth rate, cell production with maximum accumulation of chlorophyll and phycobilliproteins were found at temperature 35 °C and 2,000 lux light intensity. But with further increase in temperature and light intensity, reduction in growth rate was observed. Carotenoid content was found maximum at 3,500 lux. Improvement in the carotenoid content with increase in light intensity is an adaptive mechanism of cyanobacterium S.platensis for photoprotection, could be a good basis for the exploitation of microalgae as a source of biopigments. PMID:24031731

  13. Genetic Basis for Geosmin Production by the Water Bloom-Forming Cyanobacterium, Anabaena ucrainica

    Directory of Open Access Journals (Sweden)

    Zhongjie Wang

    2014-12-01

    Full Text Available Geosmin is a common, musty-smelling sesquiterpene, principally produced by cyanobacteria. Anabaena ucrainica (Schhorb. Watanabe, a water bloom-forming cyanobacterium, is the geosmin producer responsible for odor problems in Dianchi and Erhai lakes in China. In this study, the geosmin synthase gene (geo of A. ucrainica and its flanking regions were identified and cloned by polymerase chain reaction (PCR and genome walking. The geo gene was found to be located in a transcription unit with two cyclic nucleotide-binding protein genes (cnb. The two cnb genes were highly similar and were predicted members of the cyclic adenosine monophosphate (cAMP receptor protein/fumarate nitrate reductase regulator (Crp–Fnr family. Phylogenetic and evolutionary analyses implied that the evolution of the geosmin genes involved a horizontal gene transfer process in cyanobacteria. These genes showed a close relationship to 2-methylisoborneol genes in origin and evolution.

  14. Two-Component Signal Transduction Systems in the Cyanobacterium Synechocystis sp. PCC 6803

    Institute of Scientific and Technical Information of China (English)

    LIU Xingguo; HUANG Wei; WU Qingyu

    2006-01-01

    Two-component systems are signal transduction systems which enable bacteria to regulate cellular functions in response to changing environmental conditions. The unicellular Synechocystis sp. PCC 6803 has become a model organism for a range of biochemical and molecular biology studies aiming at investigating environmental stress response. The publication of the complete genome sequence of the cyanobacterium Synechocystis sp. PCC 6803 provided a tremendous stimulus for research in this field, and at least 80 open reading frames were identified as members of the two-component signal transduction systems in this single species of cyanobacteria. To date, functional roles have been determined for only a limited number of such proteins. This review summarizes our current knowledge about the two-component signal transduction systems in Synechocystis sp. PCC 6803 and describes recent achievements in elucidating the functional roles of these systems.

  15. Lysis of a Single Cyanobacterium for Whole Genome Amplification

    Directory of Open Access Journals (Sweden)

    Richard N. Zare

    2013-08-01

    Full Text Available Bacterial species from natural environments, exhibiting a great degree of genetic diversity that has yet to be characterized, pose a specific challenge to whole genome amplification (WGA from single cells. A major challenge is establishing an effective, compatible, and controlled lysis protocol. We present a novel lysis protocol that can be used to extract genomic information from a single cyanobacterium of Synechocystis sp. PCC 6803 known to have multilayer cell wall structures that resist conventional lysis methods. Simple but effective strategies for releasing genomic DNA from captured cells while retaining cellular identities for single-cell analysis are presented. Successful sequencing of genetic elements from single-cell amplicons prepared by multiple displacement amplification (MDA is demonstrated for selected genes (15 loci nearly equally spaced throughout the main chromosome.

  16. The regulation of HanA during heterocyst development in cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Lu, Jing-Jing; Shi, Lei; Chen, Wen-Li; Wang, Li

    2014-10-01

    In response to deprivation of combined nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 develops heterocyst, which is specifically involved in the nitrogen fixation. In this study, we focused on the regulation of HanA, a histone-like protein, in heterocyst development. Electrophoretic mobility shift assay results showed that NtcA, a global nitrogen regulator necessary for heterocyst differentiation, could bind to two NtcA-binding motifs in the hanA promoter region. qPCR results also showed that NtcA may regulate the expression of hanA. By using the hanA promoter-controlled gfp as a reporter gene and performing western blot we found that the amount of HanA in mature heterocysts was decreased gradually.

  17. Metabolomic analysis of NAD kinase-deficient mutants of the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Ishikawa, Yuuma; Miyagi, Atsuko; Haishima, Yuto; Ishikawa, Toshiki; Nagano, Minoru; Yamaguchi, Masatoshi; Hihara, Yukako; Kawai-Yamada, Maki

    2016-10-20

    NAD kinase (NADK) phosphorylates NAD(H) to NADP(H). The enzyme has a crucial role in the regulation of the NADP(H)/NAD(H) ratio in various organisms. The unicellular cyanobacterium Synechocystis sp. PCC 6803 possesses two NADK-encoding genes, sll1415 and slr0400. To elucidate the metabolic change in NADK-deficient mutants growing under photoautotrophic conditions, we conducted metabolomic analysis using capillary electrophoresis mass spectrometry (CE-MS). The growth curves of the wild-type parent (WT) and NADK-deficient mutants (Δ1415 and Δ0400) did not show any differences under photoautotrophic conditions. The NAD(P)(H) balance showed abnormality in both mutants. However, only the metabolite pattern of Δ0400 showed differences compared to WT. These results indicated that the two NADK isoforms have distinct functions in cyanobacterial metabolism. Copyright © 2016 Elsevier GmbH. All rights reserved.

  18. Sll1783, a monooxygenase associated with polysaccharide processing in the unicellular cyanobacterium Synechocystis PCC 6803.

    Science.gov (United States)

    Miranda, Hélder; Immerzeel, Peter; Gerber, Lorenz; Hörnaeus, Katarina; Lind, Sara Bergström; Pattanaik, Bagmi; Lindberg, Pia; Mamedov, Fikret; Lindblad, Peter

    2017-10-01

    Cyanobacteria play a pivotal role as the primary producer in many aquatic ecosystems. The knowledge on the interacting processes of cyanobacteria with its environment - abiotic and biotic factors - is still very limited. Many potential exocytoplasmic proteins in the model unicellular cyanobacterium Synechocystis PCC 6803 have unknown functions and their study is essential to improve our understanding of this photosynthetic organism and its potential for biotechnology use. Here we characterize a deletion mutant of Synechocystis PCC 6803, Δsll1783, a strain that showed a remarkably high light resistance which is related with its lower thylakoid membrane formation. Our results suggests Sll1783 to be involved in a mechanism of polysaccharide degradation and uptake and we hypothesize it might function as a sensor for cell density in cyanobacterial cultures. © 2017 Scandinavian Plant Physiology Society.

  19. ADP-ribosylation of glutamine synthetase in the cyanobacterium Synechocystis sp. strain PCC 6803.

    Science.gov (United States)

    Silman, N J; Carr, N G; Mann, N H

    1995-06-01

    Glutamine synthetase (GS) inactivation was observed in crude cell extracts and in the high-speed supernatant fraction from the cyanobacterium Synechocystis sp. strain PCC 6803 following the addition of ammonium ions, glutamine, or glutamate. Dialysis of the high-speed supernatant resulted in loss of inactivation activity, but this could be restored by the addition of NADH, NADPH, or NADP+ and, to a lesser extent, NAD+, suggesting that inactivation of GS involved ADP-ribosylation. This form of modification was confirmed both by labelling experiments using [32P]NAD+ and by chemical analysis of the hydrolyzed enzyme. Three different forms of GS, exhibiting no activity, biosynthetic activity only, or transferase activity only, could be resolved by chromatography, and the differences in activity were correlated with the extent of the modification. Both biosynthetic and transferase activities were restored to the completely inactive form of GS by treatment with phosphodiesterase.

  20. Sesquiterpenes of the geosmin-producing cyanobacterium Calothrix PCC 7507 and their toxicity to invertebrates.

    Science.gov (United States)

    Höckelmann, Claudia; Becher, Paul G; von Reuss, Stephan H; Jüttner, Friedrich

    2009-01-01

    The occurrence of sesquiterpenes was investigated with the geosmin-producing cyanobacterium Calothrix PCC 7507. The essential oil obtained by vacuum destillation was studied in more detail by GC-MS methods and superposition with authentic compounds. Geosmin was the dominating compound while the other sesquiterpenes were minor components. Sesquiterpenes that have not been described before in cyanobacteria were isodihydroagarofuran, eremophilone and 6,11-epoxyisodaucane. Closed-loop stripping analysis revealed that most of the sesquiterpenes were found in the biomass of Calothrix, while eremophilone was mainly observed in the medium of the axenic culture. Eremophilone showed acute toxicity (LC50) against Chironomus riparius (insecta) at 29 microM and against Thamnocephalus platyurus (crustacea) at 22 microM. The compound was not toxic for Plectus cirratus (nematoda). 6,11-Epoxyisodaucane and isodihydroagarofuran exhibited no toxicity to invertebrates when applied in concentrations up to 100 microM.

  1. UV-B-induced Oxidative Damage and Protective Role of Exopolysaccharides in Desert Cyanobacterium Microcoleus vaginatus

    Institute of Scientific and Technical Information of China (English)

    Lan-Zhou Chen; Gao-Hong Wang; Song Hong; An Liu; Cheng Li; Yong-Ding Liu

    2009-01-01

    UV-B-induced oxidative damage and the protective effect of exopolysaccharides (EPS) in Microcoleus vaginatus, a cyanobacterium isolated from desert crust, were investigated. After being irradiated with UV-B radiation, photosynthetic activity (Fv/Fm), cellular total carbohydrates, EPS and sucrose production of irradiated cells decreased, while reducing sugars, reactive oxygen species (ROS) generation, malondialdehyde (MDA) production and DNA strand breaks increased significantly. However, when pretreated with 100 mg/L exogenous EPS, EPS production in the culture medium of UV-B stressed cells decreased significantly; Fv/Fm, cellular total carbohydrates, reducing sugars and sucrose synthase (SS) activity of irradiated cells increased significantly, while ROS generation, MDA production and DNA strand breaks of irradiated cells decreased significantly. The results suggested that EPS exhibited a significant protective effect on DNA strand breaks and lipid peroxidation by effectively eliminating ROS induced by UV-B radiation in M. vaginatus.

  2. Diacylglycerolipids isolated from a thermophile cyanobacterium from the Euganean hot springs.

    Science.gov (United States)

    Marcolongo, Gabriele; de Appolonia, Francesca; Venzo, Alfonso; Berrie, Christopher P; Carofiglio, Tommaso; Ceschi Berrini, Cristina

    2006-07-10

    The Phormidium sp. ETS-05 thermophile blue-green alga is one of the most typical and widespread species of cyanobacteria of the thermal muds of the Euganean hot springs, the therapeutic properties of which have been known since ancient times. The polar diacylglycerolipids of this cyanobacterium consists of monogalactosyldiacylglycerol, digalactosyldiacylglycerol, sulfoquinovosyldiacylglycerol and phosphatidylglycerol. We have isolated and purified these four diacylglycerolipids from ETS-05, and then analysed them for their quantitative and structural features and fatty acid contents. The monogalactosyldiacylglycerol and digalactosyldiacylglycerol show a marked presence of polyunsaturated fatty acids, of which C18 : 4 is the most common. We propose that these glycoglycerolipids can be used as markers for monitoring the thermal mud colonisation process.

  3. Introduction of a synthetic CO₂-fixing photorespiratory bypass into a cyanobacterium.

    Science.gov (United States)

    Shih, Patrick M; Zarzycki, Jan; Niyogi, Krishna K; Kerfeld, Cheryl A

    2014-04-01

    Global photosynthetic productivity is limited by the enzymatic assimilation of CO2 into organic carbon compounds. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), the carboxylating enzyme of the Calvin-Benson cycle, poorly discriminates between CO2 and O2, leading to photorespiration and the loss of fixed carbon and nitrogen. With the advent of synthetic biology, it is now feasible to design, synthesize, and introduce biochemical pathways in vivo. We engineered a synthetic photorespiratory bypass based on the 3-hydroxypropionate bi-cycle into the model cyanobacterium, Synechococcus elongatus sp. PCC 7942. The heterologously expressed cycle is designed to function as both a photorespiratory bypass and an additional CO2-fixing pathway, supplementing the Calvin-Benson cycle. We demonstrate the function of all six introduced enzymes and identify bottlenecks to be targeted in subsequent bioengineering. These results have implications for efforts to improve photosynthesis and for the "green" production of high value products of biotechnological interest.

  4. BMAA Inhibits Nitrogen Fixation in the Cyanobacterium Nostoc sp. PCC 7120

    Directory of Open Access Journals (Sweden)

    Birgitta Bergman

    2013-08-01

    Full Text Available Cyanobacteria produce a range of secondary metabolites, one being the neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA, proposed to be a causative agent of human neurodegeneration. As for most cyanotoxins, the function of BMAA in cyanobacteria is unknown. Here, we examined the effects of BMAA on the physiology of the filamentous nitrogen-fixing cyanobacterium Nostoc sp. PCC 7120. Our data show that exogenously applied BMAA rapidly inhibits nitrogenase activity (acetylene reduction assay, even at micromolar concentrations, and that the inhibition was considerably more severe than that induced by combined nitrogen sources and most other amino acids. BMAA also caused growth arrest and massive cellular glycogen accumulation, as observed by electron microscopy. With nitrogen fixation being a process highly sensitive to oxygen species we propose that the BMAA effects found here may be related to the production of reactive oxygen species, as reported for other organisms.

  5. Temporal Gene Expression of the Cyanobacterium Arthrospira in Response to Gamma Rays.

    Science.gov (United States)

    Badri, Hanène; Monsieurs, Pieter; Coninx, Ilse; Nauts, Robin; Wattiez, Ruddy; Leys, Natalie

    2015-01-01

    The edible cyanobacterium Arthrospira is resistant to ionising radiation. The cellular mechanisms underlying this radiation resistance are, however, still largely unknown. Therefore, additional molecular analysis was performed to investigate how these cells can escape from, protect against, or repair the radiation damage. Arthrospira cells were shortly exposed to different doses of 60Co gamma rays and the dynamic response was investigated by monitoring its gene expression and cell physiology at different time points after irradiation. The results revealed a fast switch from an active growth state to a kind of 'survival modus' during which the cells put photosynthesis, carbon and nitrogen assimilation on hold and activate pathways for cellular protection, detoxification, and repair. The higher the radiation dose, the more pronounced this global emergency response is expressed. Genes repressed during early response, suggested a reduction of photosystem II and I activity and reduced tricarboxylic acid (TCA) and Calvin-Benson-Bassham (CBB) cycles, combined with an activation of the pentose phosphate pathway (PPP). For reactive oxygen species detoxification and restoration of the redox balance in Arthrospira cells, the results suggested a powerful contribution of the antioxidant molecule glutathione. The repair mechanisms of Arthrospira cells that were immediately switched on, involve mainly proteases for damaged protein removal, single strand DNA repair and restriction modification systems, while recA was not induced. Additionally, the exposed cells showed significant increased expression of arh genes, coding for a novel group of protein of unknown function, also seen in our previous irradiation studies. This observation confirms our hypothesis that arh genes are key elements in radiation resistance of Arthrospira, requiring further investigation. This study provides new insights into phasic response and the cellular pathways involved in the radiation resistance of

  6. Temporal Gene Expression of the Cyanobacterium Arthrospira in Response to Gamma Rays.

    Directory of Open Access Journals (Sweden)

    Hanène Badri

    Full Text Available The edible cyanobacterium Arthrospira is resistant to ionising radiation. The cellular mechanisms underlying this radiation resistance are, however, still largely unknown. Therefore, additional molecular analysis was performed to investigate how these cells can escape from, protect against, or repair the radiation damage. Arthrospira cells were shortly exposed to different doses of 60Co gamma rays and the dynamic response was investigated by monitoring its gene expression and cell physiology at different time points after irradiation. The results revealed a fast switch from an active growth state to a kind of 'survival modus' during which the cells put photosynthesis, carbon and nitrogen assimilation on hold and activate pathways for cellular protection, detoxification, and repair. The higher the radiation dose, the more pronounced this global emergency response is expressed. Genes repressed during early response, suggested a reduction of photosystem II and I activity and reduced tricarboxylic acid (TCA and Calvin-Benson-Bassham (CBB cycles, combined with an activation of the pentose phosphate pathway (PPP. For reactive oxygen species detoxification and restoration of the redox balance in Arthrospira cells, the results suggested a powerful contribution of the antioxidant molecule glutathione. The repair mechanisms of Arthrospira cells that were immediately switched on, involve mainly proteases for damaged protein removal, single strand DNA repair and restriction modification systems, while recA was not induced. Additionally, the exposed cells showed significant increased expression of arh genes, coding for a novel group of protein of unknown function, also seen in our previous irradiation studies. This observation confirms our hypothesis that arh genes are key elements in radiation resistance of Arthrospira, requiring further investigation. This study provides new insights into phasic response and the cellular pathways involved in the radiation

  7. Sorption and desorption studies of chromium(VI) from nonviable cyanobacterium Nostoc muscorum biomass

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, V.K. [Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667 (India)], E-mail: vinodfcy@iitr.ernet.in; Rastogi, A. [Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2008-06-15

    This communication presents results pertaining to the sorptive and desorptive studies carried out on chromium(VI) removal onto nonviable freshwater cyanobacterium (Nostoc muscorum) biomass. Influence of varying the conditions for removal of chromium(VI), such as the pH of aqueous solution, the dosage of biosorbent, the contact time with the biosorbent, the temperature for the removal of chromium, the effect of light metal ions and the adsorption-desorption studies were investigated. Sorption interaction of chromium on to cyanobacterial species obeyed both the first and the second-order rate equation and the experimental data showed good fit with both the Langmuir and freundlich adsorption isotherm models. The maximum adsorption capacity was 22.92 mg/g at 25 {sup o}C and pH 3.0. The adsorption process was endothermic and the values of thermodynamic parameters of the process were calculated. Various properties of the cyanobacterium, as adsorbent, explored in the characterization part were chemical composition of the adsorbent, surface area calculation by BET method and surface functionality by FTIR. Sorption-desorption of chromium into inorganic solutions and distilled water were observed and this indicated the biosorbent could be regenerated using 0.1 M HNO{sub 3} and EDTA with upto 80% recovery. The biosorbents were reused in five biosorption-desorption cycles without a significant loss in biosorption capacity. Thus, this study demonstrated that the cyanobacterial biomass N. muscorum could be used as an efficient biosorbent for the treatment of chromium(VI) bearing wastewater.

  8. Cellular responses and bioremoval of nonylphenol by the bloom-forming cyanobacterium Planktothrix agardhii 1113

    Science.gov (United States)

    Medvedeva, Nadezda; Zaytseva, Tatyana; Kuzikova, Irina

    2017-07-01

    Nonylphenol (NP) is extensively used in agricultural, industrial and household applications. Moreover, NP is the major breakdown product of the nonionic surfactants, nonylphenol ethoxylates (NPEOs), the most widely used group of surfactants. Nonylphenol is persistent in the environment, highly toxic to aquatic organisms and is a potential endocrine disruptor. NP and NPEOs have been identified as priority hazardous substances under the Environmental Quality Standards Directive 2013/39/EU and are referred to in the list of substances of particular risk to the Baltic Sea. The toxicity of NP to the bloom-forming cyanobacterium Planktothrix agardhii 1113 isolated from the eastern Gulf of Finland, Baltic Sea and the bioremoval of NP by P. agardhii were studied. NP in concentrations > 0.4 mg L- 1 suppressed cyanobacterial growth. The median effective concentration of NP for P. agardhii after 4 days of treatment (EC50) was 1.5 mg L- 1. The removal of NP from the culture medium was primarily due to abiotic processes and biodegradation by the cyanobacterium rather than sorption by the cells. NP significantly increased the photosynthetic pigments, extracellular proteins and soluble exopolysaccharides content. The cyanobacterial growth inhibition was accompanied by the increased synthesis of microcystin dm-RR and of the odorous metabolites, geosmin and 2-methylisoborneol (MIB), by P. agardhii 1113. NP also notably increased the microcystin released into the environment. Increased levels of extracellular proteins, soluble exopolysaccharides, microcystins and odorous metabolites may affect the microbial loop in aquatic ecosystems. An increased level of malondialdehyde (MDA) was indicative of the formation of free radicals in P. agardhii under NP stress, whereas increased levels of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and proline indicated the occurrence of a scavenging mechanism.

  9. Endophytic colonization of rice (Oryza sativa L. by the diazotrophic bacterium Burkholderia kururiensis and its ability to enhance plant growth

    Directory of Open Access Journals (Sweden)

    Katherine A. Mattos

    2008-09-01

    Full Text Available Burkholderia kururiensis is a diazotrophic bacterium originally isolated from a polluted aquifer environment and presents a high level of similarity with the rice endophyte "B. brasilensis" species. This work assessed the ability of B. kururiensis to endophytically colonize rice plantlets by monitoring different tissues of root-inoculated plants for the presence of bacterial growth in different media, electron microscopy and by 16S rDNA analysis. Observations of roots, stems and leaves of inoculated rice plantlets by electron microscopy revealed B. kururiensis colonization predominantly on root hair zones, demonstrating endophytic colonization primarily through the endodermis, followed by spreading into xylem vessels, a possible pathway leading to aerial parts. Although indifferent for the bacterial growth itself, addition of a nitrogen source was a limiting factor for endophytic colonization. As endophytic colonization was directly associated to an enhanced plant development, production of phytohormone auxin/indole-3-acetic acid by B. kururiensis was assayed with transgenic rice plantlets containing an auxin-responsive reporter (DR5-GUS. Our findings suggest the ability of auxin production by plant-associated B. kururiensis which may have a stimulatory effect on plant development, as evidenced by activation of DR5-GUS. We hereby demonstrate, for the first time, the ability of B. kururiensis to endophytically colonize rice, promoting both plant growth and rice grain yield.Burkholderia kururiensis é uma bactéria diazotrófica, originalmente isolada de um ambiente aquático poluído e apresenta alto nível de similaridade com a espécie endofítica "B. brasilensis" encontrada na planta de arroz. Este artigo demonstrou a habilidade de B. kururiensis colonizar endofiticamente plântulas de arroz, após esta bactéria ter sido inoculada na raiz das plantas. Esta capacidade foi confirmada pelo crescimento bacteriano em diferentes tecidos da planta

  10. Assessment of the dinitrogen released as ammonium and dissolved organic nitrogen by unicellular and filamentous marine diazotrophic cyanobacteria grown in culture

    Directory of Open Access Journals (Sweden)

    Hugo eBerthelot

    2015-10-01

    Full Text Available The dinitrogen (N2 released as dissolved nitrogen (DN has been compared in batch cultures of four marine diazotrophic cyanobacteria: the colony forming Trichodesmium IMS101 and the unicellular strains Cyanothece ATCC51142, Crocosphaera watsonii WH8501 and WH0003. Two approaches were conducted for this purpose. The first approach consisted in the comparison of the total accumulation of fixed N2 in the culture (both in dissolved and particulate pools with the net N2 fixation rates (i. e. the fixed N2 incorporated only in the particulate fraction after 15N2 incubation. The difference between the two measures accounted for the fixed N2 released as DN. The second approach consisted in the direct measure of the 15N-enrichment of ammonium (NH4+ and dissolved organic N (DON following the 15N2 incubations. The N2 released as DN accounted for ~0 - 20 % and ~1 % of the N2 fixed after 24 h in the first and second approach, respectively. We show that the recent methodological improvements in the net N2 fixation determination applied in this study tend to reconcile the two approaches that formerly led to contrasted values. However, the large analytical uncertainties of the first approach limit its reliability. Thus, the direct determination of the 15N-enrichment of the dissolved pool remains the best tool to assess the fixed N2 released in the DN pool, in particular as it allows shorter incubation times. There were no clear patterns detected between the filamentous Trichodesmium and unicellular strains, neither in terms of the amount of N2 released as DN nor in terms of the proportion of NH4+ relative to DON. This suggests that N2 release processes are shared among the filamentous and free living diazotrophs.

  11. Diazotrophic microbial mats

    NARCIS (Netherlands)

    Severin, I.; Stal, L.J.; Seckbach, J.; Oren, A.

    2010-01-01

    Microbial mats have been the focus of scientific research for a few decades. These small-scale ecosystems are examples of versatile benthic communities of microorganisms, usually dominated by phototrophic bacteria (e.g., Krumbein et al., 1977; Jørgensen et al., 1983). They develop as vertically stra

  12. D1 protein turnover is involved in protection of Photosystem II against UV-B induced damage in the cyanobacterium Arthrospira (Spirulina) platensis.

    Science.gov (United States)

    Wu, Hongyan; Abasova, Leyla; Cheregi, Otilia; Deák, Zsuzsanna; Gao, Kunshan; Vass, Imre

    2011-01-01

    By using two strains of Arthrospira (Spirulina)platensis, an economically important filamentous cyanobacterium, we compared the impairment of PSII activity and loss of D1 protein content under UV-B radiation. Our study showed that UV-B radiation induced a gradual loss of the oxygen-evolving activity to about 56% after 180 min UV-B irradiation both in strains 439 and D-0083, which have been kept under indoor and an outdoor culturing conditions, respectively for a prolonged period of time. The loss of oxygen evolution was accelerated in both strains in the presence of lincomycin, an inhibitor of protein synthesis, and the amount of D1 protein showed a decrease comparable to that of oxygen evolution during the UV-B exposure. However, the UV-B induced loss of oxygen-evolving activity and D1 protein amount was largely prevented when A. platensis cells were exposed to UV-B irradiance supplemented with visible light. Comparison of the two strains also showed a smaller extent of D1 protein synthesis dependent PSII repair in the indoor strain. Our results show that turnover of the D1 protein is an important defense mechanism to counteract the UV-B induced damage of PSII in A. platensis, and also that visible light plays an important role in maintaining the function of PSII under simultaneous exposure to UV-B and visible light.

  13. Identification of the n-1 fatty acid as an antibacterial constituent from the edible freshwater cyanobacterium Nostoc verrucosum.

    Science.gov (United States)

    Oku, Naoya; Yonejima, Kohsuke; Sugawa, Takao; Igarashi, Yasuhiro

    2014-01-01

    The cyanobacterium Nostoc verrucosum occurs in cool, clear streams and its gelatinous colonies, called "ashitsuki," have been eaten in ancient Japan. Its ethanolic extract was found to inhibit the growth of Gram-positive bacteria and activity-guided fractionation yielded an unusual n-1 fatty acid, (9Z,12Z)-9,12,15-hexadecatrienoic acid (1), as one of the active principles. It inhibited the growth of Staphylococcus aureus at MIC 64 μg/mL.

  14. Discovery of Rare and Highly Toxic Microcystins from Lichen-Associated Cyanobacterium Nostoc sp. Strain IO-102-I

    OpenAIRE

    Oksanen, Ilona; Jokela, Jouni; Fewer, David P.; Wahlsten, Matti; Rikkinen, Jouko; Sivonen, Kaarina

    2004-01-01

    The production of hepatotoxic cyclic heptapeptides, microcystins, is almost exclusively reported from planktonic cyanobacteria. Here we show that a terrestrial cyanobacterium Nostoc sp. strain IO-102-I isolated from a lichen association produces six different microcystins. Microcystins were identified with liquid chromatography-UV mass spectrometry by their retention times, UV spectra, mass fragmentation, and comparison to microcystins from the aquatic Nostoc sp. strain 152. The dominant micr...

  15. Short Communication: Effects of temperature on growth, pigment composition and protein content of an Antarctic Cyanobacterium Nostoc commune

    Directory of Open Access Journals (Sweden)

    RANJANA TRIPATHI

    2012-11-01

    Full Text Available Tripathi R, Dhuldhaj UP, Singh S. 2012. Short Communication: Effects of temperature on growth, pigment composition and protein content of an Antarctic Cyanobacterium Nostoc commune. Nusantara Bioscience 4: 134-137. Effect of temperature variation on biomass accumulation, pigment composition and protein content were studied for the cyanobacterium Nostoc commune, isolated from Antarctica. Results confirmed the psychrotrophic behavior (optimum growth temperature 25◦C of the cyanobacterium. Low temperature increased the duration of lag phase and exponential growth phase. Maximum increase in biomass was recorded on 24th day at 25◦C and on 12th day at 50C. The downshift from 25 to 5◦C had almost negligible effect on chl a content. Maximal protein content was recorded for cultures growing at 50C on 12th day. The carotenoids/chl a ratio was maximum (2.48 at 50C on 9th day. It remained almost constant for cultures growing at 5 and 350C. There was an induction in protein synthesis following downshift in temperature from 25 to 5◦C.

  16. Responses of a rice-field cyanobacterium Anabaena siamensis TISTR-8012 upon exposure to PAR and UV radiation.

    Science.gov (United States)

    Rastogi, Rajesh P; Incharoensakdi, Aran; Madamwar, Datta

    2014-10-15

    The effects of PAR and UV radiation and subsequent responses of certain antioxidant enzymatic and non-enzymatic defense systems were studied in a rice field cyanobacterium Anabaena siamensis TISTR 8012. UV radiation resulted in a decline in growth accompanied by a decrease in chlorophyll a and photosynthetic efficiency. Exposure of cells to UV radiation significantly affected the differentiation of vegetative cells into heterocysts or akinetes. UV-B radiation caused the fragmentation of the cyanobacterial filaments conceivably due to the observed oxidative stress. A significant increase of reactive oxygen species in vivo and DNA strand breaks were observed in UV-B exposed cells followed by those under UV-A and PAR radiation, respectively. The UV-induced oxidative damage was alleviated due to an induction of antioxidant enzymatic/non-enzymatic defense systems. In response to UV irradiation, the studied cyanobacterium exhibited a significant increase in antioxidative enzyme activities of superoxide dismutase, catalase and peroxidase. Moreover, the cyanobacterium also synthesized some UV-absorbing/screening substances. HPLC coupled with a PDA detector revealed the presence of three compounds with UV-absorption maxima at 326, 331 and 345 nm. The induction of the biosynthesis of these UV-absorbing compounds was found under both PAR and UV radiation, thus suggesting their possible function as an active photoprotectant.

  17. Effects of Cylindrospermopsin Producing Cyanobacterium and Its Crude Extracts on a Benthic Green Alga-Competition or Allelopathy?

    Science.gov (United States)

    B-Béres, Viktória; Vasas, Gábor; Dobronoki, Dalma; Gonda, Sándor; Nagy, Sándor Alex; Bácsi, István

    2015-10-30

    Cylindrospermopsin (CYN) is a toxic secondary metabolite produced by filamentous cyanobacteria which could work as an allelopathic substance, although its ecological role in cyanobacterial-algal assemblages is mostly unclear. The competition between the CYN-producing cyanobacterium Chrysosporum (Aphanizomenon) ovalisporum, and the benthic green alga Chlorococcum sp. was investigated in mixed cultures, and the effects of CYN-containing cyanobacterial crude extract on Chlorococcum sp. were tested by treatments with crude extracts containing total cell debris, and with cell debris free crude extracts, modelling the collapse of a cyanobacterial water bloom. The growth inhibition of Chlorococcum sp. increased with the increasing ratio of the cyanobacterium in mixed cultures (inhibition ranged from 26% to 87% compared to control). Interestingly, inhibition of the cyanobacterium growth also occurred in mixed cultures, and it was more pronounced than it was expected. The inhibitory effects of cyanobacterial crude extracts on Chlorococcum cultures were concentration-dependent. The presence of C. ovalisporum in mixed cultures did not cause significant differences in nutrient content compared to Chlorococcum control culture, so the growth inhibition of the green alga could be linked to the presence of CYN and/or other bioactive compounds.

  18. Effects of Cylindrospermopsin Producing Cyanobacterium and Its Crude Extracts on a Benthic Green Alga—Competition or Allelopathy?

    Science.gov (United States)

    B-Béres, Viktória; Vasas, Gábor; Dobronoki, Dalma; Gonda, Sándor; Nagy, Sándor Alex; Bácsi, István

    2015-01-01

    Cylindrospermopsin (CYN) is a toxic secondary metabolite produced by filamentous cyanobacteria which could work as an allelopathic substance, although its ecological role in cyanobacterial-algal assemblages is mostly unclear. The competition between the CYN-producing cyanobacterium Chrysosporum (Aphanizomenon) ovalisporum, and the benthic green alga Chlorococcum sp. was investigated in mixed cultures, and the effects of CYN-containing cyanobacterial crude extract on Chlorococcum sp. were tested by treatments with crude extracts containing total cell debris, and with cell debris free crude extracts, modelling the collapse of a cyanobacterial water bloom. The growth inhibition of Chlorococcum sp. increased with the increasing ratio of the cyanobacterium in mixed cultures (inhibition ranged from 26% to 87% compared to control). Interestingly, inhibition of the cyanobacterium growth also occurred in mixed cultures, and it was more pronounced than it was expected. The inhibitory effects of cyanobacterial crude extracts on Chlorococcum cultures were concentration-dependent. The presence of C. ovalisporum in mixed cultures did not cause significant differences in nutrient content compared to Chlorococcum control culture, so the growth inhibition of the green alga could be linked to the presence of CYN and/or other bioactive compounds. PMID:26528991

  19. Molecular exploration of the highly radiation resistant cyanobacterium Arthrospira sp. PCC 8005

    Science.gov (United States)

    Badri, Hanène; Leys, Natalie; Wattiez, Ruddy

    Arthrospira (Spirulina) is a photosynthetic cyanobacterium able to use sunlight to release oxygen from water and remove carbon dioxide and nitrate from water. In addition, it is suited for human consumption (edible). For these traits, the cyanobacterium Arthrospira sp. PCC 8005 was selected by the European Space Agency (ESA) as part of the life support system MELiSSA for recycling oxygen, water, and food during future long-haul space missions. However, during such extended missions, Arthrospira sp. PCC 8005 will be exposed to continuous artificial illumination and harmful cosmic radiation. The aim of this study was to investigate how Arthrospira will react and behave when exposed to such stress environment. The cyanobacterium Arthrospira sp. PCC 8005 was exposed to high gamma rays doses in order to unravel in details the response of this bacterium following such stress. Test results showed that after acute exposure to high doses of 60Co gamma radiation upto 3200 Gy, Arthrospira filaments were still able to restart photosynthesis and proliferate normally. Doses above 3200 Gy, did have a detrimental effect on the cells, and delayed post-irradiation proliferation. The photosystem activity, measured as the PSII quantum yield immediately after irradiation, decreased significantly at radiation doses above 3200 Gy. Likewise through pigment content analysis a significant decrease in phycocyanin was observed following exposure to 3200 Gy. The high tolerance of this bacterium to 60Co gamma rays (i.e. ca. 1000x more resistant than human cells for example) raised our interest to investigate in details the cellular and molecular mechanisms behind this amazing resistance. Optimised DNA, RNA and protein extraction methods and a new microarray chip specific for Arthrospira sp. PCC 8005 were developed to identify the global cellular and molecular response following exposure to 3200 Gy and 5000 Gy A total of 15,29 % and 30,18 % genes were found differentially expressed in RNA

  20. Lab-Scale Study of the Calcium Carbonate Dissolution and Deposition by Marine Cyanobacterium Phormidium subcapitatum

    Science.gov (United States)

    Karakis, S. G.; Dragoeva, E. G.; Lavrenyuk, T. I.; Rogochiy, A.; Gerasimenko, L. M.; McKay, D. S.; Brown, I. I.

    2006-01-01

    Suggestions that calcification in marine organisms changes in response to global variations in seawater chemistry continue to be advanced (Wilkinson, 1979; Degens et al. 1985; Kazmierczak et al. 1986; R. Riding 1992). However, the effect of [Na+] on calcification in marine cyanobacteria has not been discussed in detail although [Na+] fluctuations reflect both temperature and sea-level fluctuations. The goal of these lab-scale studies therefore was to study the effect of environmental pH and [Na+] on CaCO3 deposition and dissolution by marine cyanobacterium Phormidium subcapitatum. Marine cyanobacterium P. subcapitatum has been cultivated in ASN-III medium. [Ca2+] fluctuations were monitored with Ca(2+) probe. Na(+) concentrations were determined by the initial solution chemistry. It was found that the balance between CaCO3 dissolution and precipitation induced by P. subcapitatum grown in neutral ASN III medium is very close to zero. No CaCO3 precipitation induced by cyanobacterial growth occurred. Growth of P. subcapitatum in alkaline ASN III medium, however, was accompanied by significant oscillations in free Ca(2+) concentration within a Na(+) concentration range of 50-400 mM. Calcium carbonate precipitation occurred during the log phase of P. subcapitatum growth while carbonate dissolution was typical for the stationary phase of P. subcapitatum growth. The highest CaCO3 deposition was observed in the range of Na(+) concentrations between 200-400 mM. Alkaline pH also induced the clamping of P. subcapitatum filaments, which appeared to have a strong affinity to envelop particles of chemically deposited CaCO3 followed by enlargement of those particles size. EDS analysis revealed the presence of Mg-rich carbonate (or magnesium calcite) in the solution containing 10-100 mM Na(+); calcite in the solution containing 200 mM Na(+); and aragonite in the solution containing with 400 mM Na(+). Typical present-day seawater contains xxmM Na(+). Early (Archean) seawater was

  1. PSP toxin release from the cyanobacterium Raphidiopsis brookii D9 (Nostocales) can be induced by sodium and potassium ions.

    Science.gov (United States)

    Soto-Liebe, Katia; Méndez, Marco A; Fuenzalida, Loreto; Krock, Bernd; Cembella, Allan; Vásquez, Mónica

    2012-12-01

    Paralytic shellfish poisoning (PSP) toxins are a group of naturally occurring neurotoxic alkaloids produced among several genera of primarily freshwater cyanobacteria and marine dinoflagellates. Although saxitoxin (STX) and analogs are all potent Na(+) channel blockers in vertebrate cells, the functional role of these compounds for the toxigenic microorganisms is unknown. Based upon the known importance of monovalent cations (such as sodium) in the maintenance of cellular homeostasis and ion channel function, we examined the effect of high extracellular concentrations of these ions on growth, cellular integrity, toxin production and release to the external medium in the filamentous freshwater cyanobacterium, Raphidiopsis brookii D9; a gonyautoxins (GTX2/3) and STX producing toxigenic strain. We observed a toxin export in response to high (17 mM) NaCl and KCl concentrations in the growth medium that was not primarily related to osmotic stress effects, compared to the osmolyte mannitol. Addition of exogenous PSP toxins with the same compositional profile as the one produced by R. brookii D9 was able to partially mitigate this effect of high Na⁺ (17 mM). The PSP toxin biosynthetic gene cluster (sxt) in D9 has two genes (sxtF and sxtM) that encode for a MATE (multidrug and toxic compound extrusion) transporter. This protein family, represented by NorM in the bacterium Vibrio parahaemolyticus, confers resistance to multiple cationic toxic agents through Na⁺/drug antiporters. Conserved domains for Na⁺ and drug recognition have been described in NorM. For the D9 sxt cluster, the Na⁺ recognition domain is conserved in both SxtF and SxtM, but the drug recognition domain differs between them. These results suggest that PSP toxins are exported directly in response to the presence of monovalent cations (Na⁺, K⁺) at least at elevated concentrations. Thus, the presence of both genes in the sxt cluster from strain D9 can be explained as a selective recognition

  2. Proteomic Analysis of the Marine Cyanobacterium Synechococcus WH8102 and Implications for Estimates of the Cellular Iron Content

    Science.gov (United States)

    Saito, M. A.; Bertrand, E. M.; Bulygin, V.; Moran, D.; Waterbury, J. B.

    2008-12-01

    The proteome of the marine cyanobacterium Synechococcus WH8102 was analyzed by nanospray liquid chromatography mass spectrometry (nLC-MS) with two major goals: to provide a first examination of the relative abundance of the most abundant proteins in this important microbe and to provide the necessary mass spectra for future quantification of biogeochemically significant proteins. Analyses of 37 nLC-MS runs of whole cell tryptic digestions and SDS-PAGE gel separated tryptic digestions resulted in a total of 636 proteins identified, 376 identified with two or more tryptic peptides. The identifications used the Sequest algorithm with stringent data filters on 54003 observed peptides, 3066 of which were unique, with a false positive rate of 2.2%. These measured proteins represent ~ 25.2% (14.8% with >= 2 peptides) of the open reading frames (ORFs) in the genome, similar to or higher than the percentage found in other cyanobacterial proteome studies thus far. The relative abundance of the more abundant proteins in the proteome was examined using the exponentially modified protein abundance index from a single nLC-MS run that identified 372 proteins (14.7% of the ORFs) from 7743 observed peptides (1224 unique peptides). Estimates of the relative abundance showed the photosynthesis and respiration category contributing approximately 32% of the total detected protein, hypothetical proteins contributing about 16%, and translation about 12%. Of biogeochemical interest, multiple types of nitrogen assimilation systems were observed to be simultaneously expressed as proteins, only 5 of the 21 B12 biosynthesis proteins were identified likely due to low abundance, and the metalloproteins metallothionein and nickel superoxide dismutase were relatively abundant. In contrast to previous predictions of a high photosystem I: photosystem II ratio of approximately 3 in the cyanobacteria and a resultant high cellular iron content, the ratio of the average relative abundances of all

  3. Molecular Cloning and Biochemical Characterization of the Iron Superoxide Dismutase from the Cyanobacterium Nostoc punctiforme ATCC 29133 and Its Response to Methyl Viologen-Induced Oxidative Stress.

    Science.gov (United States)

    Moirangthem, Lakshmipyari Devi; Ibrahim, Kalibulla Syed; Vanlalsangi, Rebecca; Stensjö, Karin; Lindblad, Peter; Bhattacharya, Jyotirmoy

    2015-12-01

    Superoxide dismutase (SOD) detoxifies cell-toxic superoxide radicals and constitutes an important component of antioxidant machinery in aerobic organisms, including cyanobacteria. The iron-containing SOD (SodB) is one of the most abundant soluble proteins in the cytosol of the nitrogen-fixing cyanobacterium Nostoc punctiforme ATCC 29133, and therefore, we investigated its biochemical properties and response to oxidative stress. The putative SodB-encoding open reading frame Npun_R6491 was cloned and overexpressed in Escherichia coli as a C-terminally hexahistidine-tagged protein. The purified recombinant protein had a SodB specific activity of 2560 ± 48 U/mg protein at pH 7.8 and was highly thermostable. The presence of a characteristic iron absorption peak at 350 nm, and its sensitivity to H2O2 and azide, confirmed that the SodB is an iron-containing SOD. Transcript level of SodB in nitrogen-fixing cultures of N. punctiforme decreased considerably (threefold) after exposure to an oxidative stress-generating herbicide methyl viologen for 4 h. Furthermore, in-gel SOD activity analysis of such cultures grown at increasing concentrations of methyl viologen also showed a loss of SodB activity. These results suggest that SodB is not the primary scavenger of superoxide radicals induced by methyl viologen in N. punctiforme.

  4. Contribution of a Sodium Ion Gradient to Energy Conservation during Fermentation in the Cyanobacterium Arthrospira (Spirulina) maxima CS-328 ▿ †

    Science.gov (United States)

    Carrieri, Damian; Ananyev, Gennady; Lenz, Oliver; Bryant, Donald A.; Dismukes, G. Charles

    2011-01-01

    Sodium gradients in cyanobacteria play an important role in energy storage under photoautotrophic conditions but have not been well studied during autofermentative metabolism under the dark, anoxic conditions widely used to produce precursors to fuels. Here we demonstrate significant stress-induced acceleration of autofermentation of photosynthetically generated carbohydrates (glycogen and sugars) to form excreted organic acids, alcohols, and hydrogen gas by the halophilic, alkalophilic cyanobacterium Arthrospira (Spirulina) maxima CS-328. When suspended in potassium versus sodium phosphate buffers at the start of autofermentation to remove the sodium ion gradient, photoautotrophically grown cells catabolized more intracellular carbohydrates while producing 67% higher yields of hydrogen, acetate, and ethanol (and significant amounts of lactate) as fermentative products. A comparable acceleration of fermentative carbohydrate catabolism occurred upon dissipating the sodium gradient via addition of the sodium-channel blocker quinidine or the sodium-ionophore monensin but not upon dissipating the proton gradient with the proton-ionophore dinitrophenol (DNP). The data demonstrate that intracellular energy is stored via a sodium gradient during autofermentative metabolism and that, when this gradient is blocked, the blockage is compensated by increased energy conversion via carbohydrate catabolism. PMID:21890670

  5. Impact of different group 2 sigma factors on light use efficiency and high salt stress in the cyanobacterium Synechocystis sp. PCC 6803.

    Directory of Open Access Journals (Sweden)

    Taina Tyystjärvi

    Full Text Available Sigma factors of RNA polymerase recognize promoters and have a central role in controlling transcription initiation and acclimation to changing environmental conditions. The cyanobacterium Synechocystis sp. PCC 6803 encodes four non-essential group 2 sigma factors, SigB, SigC, SigD and SigE that closely resemble the essential SigA factor. Three out of four group 2 sigma factors were simultaneously inactivated and acclimation responses of the triple inactivation strains were studied. All triple inactivation strains grew slowly in low light, and our analysis suggests that the reason is a reduced capacity to adjust the perception of light. Simultaneous inactivation of SigB and SigD hampered growth also in high light. SigB is the most important group 2 sigma factor for salt acclimation, and elimination of all the other group 2 sigma factors slightly improved the salt tolerance of Synechocystis. Presence of only SigE allowed full salt acclimation including up-regulation of hspA and ggpS genes, but more slowly than SigB. Cells with only SigD acclimated to high salt but the acclimation processes differed from those of the control strain. Presence of only SigC prevented salt acclimation.

  6. Ammonium/methylammonium permeases of a Cyanobacterium. Identification and analysis of three nitrogen-regulated amt genes in synechocystis sp. PCC 6803.

    Science.gov (United States)

    Montesinos, M L; Muro-Pastor, A M; Herrero, A; Flores, E

    1998-11-20

    Ammonium is an important nitrogen source for many microorganisms and plants. Ammonium transporters whose activity can be probed with [14C]methylammonium have been described in several organisms including some cyanobacteria, and amt genes encoding ammonium/methylammonium permeases have been recently identified in yeast, Arabidopsis thaliana, and some bacteria. The unicellular cyanobacterium Synechocystis sp. PCC 6803 exhibited a [14C]methylammonium uptake activity that was inhibited by externally added ammonium. Three putative amt genes that are found in the recently published complete sequence of the chromosome of strain PCC 6803 were inactivated by insertion of antibiotic resistance-encoding gene-cassettes. The corresponding mutant strains were impaired in uptake of [14C]methylammonium. Open reading frame sll0108 (amt1) was responsible for a high affinity uptake activity (Ks for methylammonium, 2.7 microM), whereas open reading frames sll1017 (amt2) and sll0537 (amt3) made minor contributions to uptake at low substrate concentrations. Expression of the three amt genes was higher in nitrogen-starved cells than in cells incubated in the presence of a source of nitrogen (either ammonium or nitrate), but amt1 was expressed at higher levels than the other two amt genes. Transcription of amt1 was found to take place from a promoter bearing the structure of the cyanobacterial promoters activated by the nitrogen control transcription factor, NtcA.

  7. Crystal Structure of Allophycocyanin from Marine Cyanobacterium Phormidium sp. A09DM.

    Science.gov (United States)

    Sonani, Ravi Raghav; Gupta, Gagan Deep; Madamwar, Datta; Kumar, Vinay

    2015-01-01

    Isolated phycobilisome (PBS) sub-assemblies have been widely subjected to X-ray crystallography analysis to obtain greater insights into the structure-function relationship of this light harvesting complex. Allophycocyanin (APC) is the phycobiliprotein always found in the PBS core complex. Phycocyanobilin (PCB) chromophores, covalently bound to conserved Cys residues of α- and β- subunits of APC, are responsible for solar energy absorption from phycocyanin and for transfer to photosynthetic apparatus. In the known APC structures, heterodimers of α- and β- subunits (known as αβ monomers) assemble as trimer or hexamer. We here for the first time report the crystal structure of APC isolated from a marine cyanobacterium (Phormidium sp. A09DM). The crystal structure has been refined against all the observed data to the resolution of 2.51 Å to Rwork (Rfree) of 0.158 (0.229) with good stereochemistry of the atomic model. The Phormidium protein exists as a trimer of αβ monomers in solution and in crystal lattice. The overall tertiary structures of α- and β- subunits, and trimeric quaternary fold of the Phormidium protein resemble the other known APC structures. Also, configuration and conformation of the two covalently bound PCB chromophores in the marine APC are same as those observed in fresh water cyanobacteria and marine red algae. More hydrophobic residues, however, constitute the environment of the chromophore bound to α-subunit of the Phormidium protein, owing mainly to amino acid substitutions in the marine protein.

  8. Comparative studies on two ferredoxins from the cyanobacterium Nostoc strain MAC.

    Science.gov (United States)

    Hutson, K G; Rogers, L J; Haslett, B G; Boulter, D; Cammack, R

    1978-06-15

    Two ferredoxins were isolated from the cyanobacterium Nostoc strain MAC grown autotrophically in the light or heterotrophically in the dark. In either case approximately three times as much ferredoxin I as ferredoxin II was obtained. Both ferredoxins had absorption maxima at 276, 282 (shoulder), 330, 423 and 465 nm in the oxidized state, and each possessed a single 2 Fe-2S active centre. Their isoelectric points were approx. 3.2. The midpoint redox potentials of the ferredoxins differed markedly; that of ferredoxin I was --350mV and that of ferredoxin II was --445mV, at pH 8.0. The midpoint potential of ferredoxin II was unusual in being pH dependent. Ferredoxin I was most active in supporting NADP+ photoreduction by chloroplasts, whereas ferredoxin II was somewhat more active in pyruvate decarboxylation by the phosphoroclastic system of Clostridum pasteurianum. Though the molecular weights of the ferredoxins determined by ultracentrifugation were the same within experimetnal error, the amino acid compositions showed marked differences. The N-terminal amino acid sequences of ferredoxins I and II were determined by means of an automatic sequencer. There are 11--12 differences between the sequences of the first 32 residues. It appears that the two ferredoxins have evolved separately to fulfil different roles in the organism.

  9. Bioprocess Engineering Aspects of Biopolymer Production by the Cyanobacterium Spirulina Strain LEB 18

    Directory of Open Access Journals (Sweden)

    Roberta Guimarães Martins

    2014-01-01

    Full Text Available Microbial biopolymers can replace environmentally damaging plastics derived from petrochemicals. We investigated biopolymer synthesis by the cyanobacterium Spirulina strain LEB 18. Autotrophic culture used unmodified Zarrouk medium or modified Zarrouk medium in which the NaNO3 content was reduced to 0.25 g L−1 and the NaHCO3 content reduced to 8.4 g L−1 or increased to 25.2 g L−1. Heterotrophic culture used modified Zarrouk medium containing 0.25 g L−1 NaNO3 with the NaHCO3 replaced by 0.2 g L−1, 0.4 g L−1, or 0.6 g L−1 of glucose (C6H12O6 or sodium acetate (CH3COONa. Mixotrophic culture used modified Zarrouk medium containing 0.25 g L−1 NaNO3 plus 16.8 g L−1 NaHCO3 with the addition of 0.2 g L−1, 0.4 g L−1, or 0.6 g L−1 of glucose or sodium acetate. The highest biopolymer yield was 44% when LEB 18 was growing autotrophically in media containing 0.25 g L−1 NaNO3 and 8.4 g L−1 NaHCO3.

  10. The antimicrobial profile of extracts of a Phormidium-like cyanobacterium changes with phosphate levels.

    Science.gov (United States)

    El Semary, Nermin Adel

    2012-02-01

    The antimicrobial activity of lipophilic extracts of mat-forming Phormidium-like cyanobacterium isolated from Egypt was investigated under different phosphate concentrations. The antimicrobial profile changed with different phosphate levels indicating metabolic changes under stressful conditions. The fractions that resulted in highest antimicrobial activity from the three different phosphate concentrations were chosen for further analyses. The bioactive compounds were identified using chromatographic and spectroscopic techniques including UV, FTIR, GC-MS and proton-NMR. The chemical analyses indicated that the compound at standard phosphate concentration was eugenol whereas the bioactive compound at half phosphate concentration was 4-tert-butylcyclohexanol. The third bioactive compound at quarter phosphate concentration was octadecanoic acid. The eugenol is known for its antimicrobial as well as pain relief properties and can be used in many pharmaceutical preparations whereas the octadecanoic acid and cyclohexanol derivative are used in some antimicrobial pharmaceuticals. The study highlights the change in antimicrobial profile of bioactive compounds derived from cyanobacteria through manipulating the concentration of a key nutrient in growth medium. This strategy can be employed for mass production of these compounds and others for future biotechnological applications.

  11. Type II Toxin–Antitoxin Systems in the Unicellular Cyanobacterium Synechocystis sp. PCC 6803

    Directory of Open Access Journals (Sweden)

    Stefan Kopfmann

    2016-07-01

    Full Text Available Bacterial toxin–antitoxin (TA systems are genetic elements, which are encoded by plasmid as well as chromosomal loci. They mediate plasmid and genomic island maintenance through post-segregational killing mechanisms but may also have milder effects, acting as mobile stress response systems that help certain cells of a population in persisting adverse growth conditions. Very few cyanobacterial TA system have been characterized thus far. In this work, we focus on the cyanobacterium Synechocystis 6803, a widely used model organism. We expand the number of putative Type II TA systems from 36 to 69 plus seven stand-alone components. Forty-seven TA pairs are located on the chromosome and 22 are plasmid-located. Different types of toxins are associated with various antitoxins in a mix and match principle. According to protein domains and experimental data, 81% of all toxins in Synechocystis 6803 likely exhibit RNase activity, suggesting extensive potential for toxicity-related RNA degradation and toxin-mediated transcriptome remodeling. Of particular interest is the Ssr8013–Slr8014 system encoded on plasmid pSYSG, which is part of a larger defense island or the pSYSX system Slr6056–Slr6057, which is linked to a bacterial ubiquitin-like system. Consequently, Synechocystis 6803 is one of the most prolific sources of new information about these genetic elements.

  12. Type II Toxin–Antitoxin Systems in the Unicellular Cyanobacterium Synechocystis sp. PCC 6803

    Science.gov (United States)

    Kopfmann, Stefan; Roesch, Stefanie K.; Hess, Wolfgang R.

    2016-01-01

    Bacterial toxin–antitoxin (TA) systems are genetic elements, which are encoded by plasmid as well as chromosomal loci. They mediate plasmid and genomic island maintenance through post-segregational killing mechanisms but may also have milder effects, acting as mobile stress response systems that help certain cells of a population in persisting adverse growth conditions. Very few cyanobacterial TA system have been characterized thus far. In this work, we focus on the cyanobacterium Synechocystis 6803, a widely used model organism. We expand the number of putative Type II TA systems from 36 to 69 plus seven stand-alone components. Forty-seven TA pairs are located on the chromosome and 22 are plasmid-located. Different types of toxins are associated with various antitoxins in a mix and match principle. According to protein domains and experimental data, 81% of all toxins in Synechocystis 6803 likely exhibit RNase activity, suggesting extensive potential for toxicity-related RNA degradation and toxin-mediated transcriptome remodeling. Of particular interest is the Ssr8013–Slr8014 system encoded on plasmid pSYSG, which is part of a larger defense island or the pSYSX system Slr6056–Slr6057, which is linked to a bacterial ubiquitin-like system. Consequently, Synechocystis 6803 is one of the most prolific sources of new information about these genetic elements. PMID:27455323

  13. Effect of Selected Plant Extracts and D- and L-Lysine on the Cyanobacterium Microcystis aeruginosa

    Directory of Open Access Journals (Sweden)

    Miquel Lürling

    2014-06-01

    Full Text Available We tested extracts from Fructus mume, Salvia miltiorrhiza and Moringa oleifera as well as L-lysine and D-Lysine as curative measures to rapidly suppress the cyanobacterium Microcystis aeruginosa NIVA-CYA 43. We tested these compounds under similar conditions to facilitate comparisons. We hypothesized that for each compound, relatively low concentrations—i.e., 5–50 mg L−1, would reduce M. aeruginosa biomass. At these low concentrations, only L-lysine caused a decline in M. aeruginosa biomass at ≥4.3 mg L−1. F. mume extract was effective to do so at high concentrations, i.e., at ≥240 mg L−1, but the others were virtually non-effective. Low pH caused by organic acids is a probable explanation for the effect of F. mume extract. No complete wipe-outs of the experimental population were achieved as Photosystem II efficiency showed a recovery after six days. L-lysine may be effective at low concentrations—meaning low material costs. However, the effect of L-lysine seems relatively short-lived. Overall, the results of our study did not support the use of the tested plant extracts and amino-acid as promising candidates for curative application in M. aeruginosa bloom control.

  14. Semicontinuous cultivation of the cyanobacterium Spirulina platensis in a closed photobioreactor

    Directory of Open Access Journals (Sweden)

    C. C. Reichert

    2006-03-01

    Full Text Available The cultivation of photosynthetic microorganisms such as the cyanobacterium Spirulina platensis has been studied by researchers in many countries because these organisms can produce products with industrial potential. We studied the specific growth rate (µx, day-1 and productivity (Px, in mg/L/day of Spirulina platensis biomass, dry weight basis of two S. platensis strains (LEB-52 and Paracas growing in aerated semicontinuous culture in two-liter Erlenmeyer flasks for 90 days (2160 h at 30°C under 2500 lux of illumination in a 12 h photoperiod. Independent of the S. platensis strain used we found that low biomass concentrations (0.50 g/L and high renewal rates (50% v/v resulted in a high specific growth rate (µx = 0.111 day-1 and high productivity (Px = 42.3 mg/L/day. These values are two to four times higher than those obtained in simple batch cultivation and indicate that the semicontinuous cultivation of S. platensis is viable.

  15. Fractionation and characterization of polysaccharides from cyanobacterium Spirulina (Arthrospira) maxima in nitrogen-limited batch culture

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By a sequentially selective extraction procedure, polysaccharides (PS) from cyanobacterium Spirulina (Arthrospira) maxima that can be bio-functionally healthy components were fractionated in four parts including the culture medium (PSCM), the external layers of the cell (PSEL), the cell wall (PSCW) and storage granules (PSSG). The four fractionated parts of polysaccharides were characterized by gas-liquid chromatography (GLC) equipped with FID and fused-silica capillary column (15 m×0.53 mm i. d.). The contents of PSCM, PSEL, PSCW and PSSG were about 2.0%, 2.6%, 10.0% and 52.0% to cell dry matter, respectively. Glucose was almost the only monosaccharide in PSSG and PSCW and most predominant in PSEL, while in PSCM, xylose, rhamnose and glucose were the main ones. Two uronic acids represented by glucuronic acid and galacturoic acid, six neutral monosaccharides including fucose, rhamnose, xylose, mannose, galactose and glucose, and two possible unidentified sugars were found in PSEL and PSCM. These data are valuable for the selective productions of high-added value sugars from Spirulina.

  16. Anoxygenic Photosynthesis Controls Oxygenic Photosynthesis in a Cyanobacterium from a Sulfidic Spring

    KAUST Repository

    Klatt, Judith M.

    2015-03-15

    Before the Earth\\'s complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39, in which this versatility is still conserved, and we show that the transition between the two photosynthetic modes follows a surprisingly simple kinetic regulation controlled by this organism\\'s affinity for H2S. Specifically, oxygenic photosynthesis is performed in addition to anoxygenic photosynthesis only when H2S becomes limiting and its concentration decreases below a threshold that increases predictably with the available ambient light. The carbon-based growth rates during oxygenic and anoxygenic photosynthesis were similar. However, Pseudanabaena FS39 additionally assimilated NO3 - during anoxygenic photosynthesis. Thus, the transition between anoxygenic and oxygenic photosynthesis was accompanied by a shift of the C/N ratio of the total bulk biomass. These mechanisms offer new insights into the way in which, despite nutrient limitation in the oxic photic zone in the mid-Proterozoic oceans, versatile cyanobacteria might have promoted oxygenic photosynthesis and total primary productivity, a key step that enabled the complete oxygenation of our planet and the subsequent diversification of life.

  17. Anoxygenic photosynthesis controls oxygenic photosynthesis in a cyanobacterium from a sulfidic spring.

    Science.gov (United States)

    Klatt, Judith M; Al-Najjar, Mohammad A A; Yilmaz, Pelin; Lavik, Gaute; de Beer, Dirk; Polerecky, Lubos

    2015-03-01

    Before the Earth's complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39, in which this versatility is still conserved, and we show that the transition between the two photosynthetic modes follows a surprisingly simple kinetic regulation controlled by this organism's affinity for H2S. Specifically, oxygenic photosynthesis is performed in addition to anoxygenic photosynthesis only when H2S becomes limiting and its concentration decreases below a threshold that increases predictably with the available ambient light. The carbon-based growth rates during oxygenic and anoxygenic photosynthesis were similar. However, Pseudanabaena FS39 additionally assimilated NO3 (-) during anoxygenic photosynthesis. Thus, the transition between anoxygenic and oxygenic photosynthesis was accompanied by a shift of the C/N ratio of the total bulk biomass. These mechanisms offer new insights into the way in which, despite nutrient limitation in the oxic photic zone in the mid-Proterozoic oceans, versatile cyanobacteria might have promoted oxygenic photosynthesis and total primary productivity, a key step that enabled the complete oxygenation of our planet and the subsequent diversification of life.

  18. Semicontinuous cultivation of the Cyanobacterium Spirulina platensis in a closed photobioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Reichert, C.C.; Costa, J.A.V. [Fundacao Universidade Federal do Rio Grande (FURG), Rio Grande, RS (Brazil). Dept. de Quimica], Email: dqmjorge@furg.br; Reinehr, C.O. [Universidade de Passo Fundo, RS (Brazil). Centro de Pesquisa em Alimentacao], Email: reinehr@upf.br

    2006-01-15

    The cultivation of photosynthetic microorganisms such as the cyanobacterium Spirulina platensis has been studied by researchers in many countries because these organisms can produce products with industrial potential. We studied the specific growth rate ({mu}{sub x}, day{sup -1}) and productivity (P{sub x}, in mg/L/day of Spirulina platensis biomass, dry weight basis) of two S. platensis strains (LEB-52 and Paracas) growing in aerated semicontinuous culture in two-liter Erlenmeyer flasks for 90 days (2160 h) at 30 deg C under 2500 lux of illumination in a 12 h photoperiod. Independent of the S. platensis strain used we found that low biomass concentrations (0.50 g/L) and high renewal rates (50% v/v) resulted in a high specific growth rate ({mu}{sub x} = 0.111 day{sup -1}) and high productivity (P{sub x} = 42.3 mg/L/day). These values are two to four times higher than those obtained in simple batch cultivation and indicate that the semicontinuous cultivation of S. platensis is viable. (author)

  19. Proteome-wide analysis and diel proteomic profiling of the cyanobacterium Arthrospira platensis PCC 8005.

    Directory of Open Access Journals (Sweden)

    Sabine Matallana-Surget

    Full Text Available The filamentous cyanobacterium Arthrospira platensis has a long history of use as a food supply and it has been used by the European Space Agency in the MELiSSA project, an artificial microecosystem which supports life during long-term manned space missions. This study assesses progress in the field of cyanobacterial shotgun proteomics and light/dark diurnal cycles by focusing on Arthrospira platensis. Several fractionation workflows including gel-free and gel-based protein/peptide fractionation procedures were used and combined with LC-MS/MS analysis, enabling the overall identification of 1306 proteins, which represents 21% coverage of the theoretical proteome. A total of 30 proteins were found to be significantly differentially regulated under light/dark growth transition. Interestingly, most of the proteins showing differential abundance were related to photosynthesis, the Calvin cycle and translation processes. A novel aspect and major achievement of this work is the successful improvement of the cyanobacterial proteome coverage using a 3D LC-MS/MS approach, based on an immobilized metal affinity chromatography, a suitable tool that enabled us to eliminate the most abundant protein, the allophycocyanin. We also demonstrated that cell growth follows a light/dark cycle in A. platensis. This preliminary proteomic study has highlighted new characteristics of the Arthrospira platensis proteome in terms of diurnal regulation.

  20. Photoregulation of morphological structure and its physiological relevance in the cyanobacterium Arthrospira (Spirulina) platensis.

    Science.gov (United States)

    Ma, Zengling; Gao, Kunshan

    2009-07-01

    The spiral structure of the cyanobacterium Arthrospira (Spirulina) platensis (Nordst.) Gomont was previously found to be altered by solar ultraviolet radiation (UVR, 280-400 nm). However, how photosynthetic active radiation (PAR, 400-700 nm) and UVR interact in regulating this morphological change remains unknown. Here, we show that the spiral structure of A. platensis (D-0083) was compressed under PAR alone at 30 degrees C, but that at 20 degrees C, the spirals compressed only when exposed to PAR with added UVR, and that UVR alone (the PAR was filtered out) did not tighten the spiral structure, although its presence accelerated morphological regulation by PAR. Their helix pitch decreased linearly as the cells received increased PAR doses, and was reversible when they were transferred back to low PAR levels. SDS-PAGE analysis showed that a 52.0 kDa periplasmic protein was more abundant in tighter filaments, which may have been responsible for the spiral compression. This spiral change together with the increased abundance of the protein made the cells more resistant to high PAR as well as UVR, resulting in a higher photochemical yield.

  1. Proteome-wide analysis and diel proteomic profiling of the cyanobacterium Arthrospira platensis PCC 8005.

    Science.gov (United States)

    Matallana-Surget, Sabine; Derock, Jérémy; Leroy, Baptiste; Badri, Hanène; Deschoenmaeker, Frédéric; Wattiez, Ruddy

    2014-01-01

    The filamentous cyanobacterium Arthrospira platensis has a long history of use as a food supply and it has been used by the European Space Agency in the MELiSSA project, an artificial microecosystem which supports life during long-term manned space missions. This study assesses progress in the field of cyanobacterial shotgun proteomics and light/dark diurnal cycles by focusing on Arthrospira platensis. Several fractionation workflows including gel-free and gel-based protein/peptide fractionation procedures were used and combined with LC-MS/MS analysis, enabling the overall identification of 1306 proteins, which represents 21% coverage of the theoretical proteome. A total of 30 proteins were found to be significantly differentially regulated under light/dark growth transition. Interestingly, most of the proteins showing differential abundance were related to photosynthesis, the Calvin cycle and translation processes. A novel aspect and major achievement of this work is the successful improvement of the cyanobacterial proteome coverage using a 3D LC-MS/MS approach, based on an immobilized metal affinity chromatography, a suitable tool that enabled us to eliminate the most abundant protein, the allophycocyanin. We also demonstrated that cell growth follows a light/dark cycle in A. platensis. This preliminary proteomic study has highlighted new characteristics of the Arthrospira platensis proteome in terms of diurnal regulation.

  2. Anilofos tolerance and its mineralization by the cyanobacterium Synechocystis sp. strain PUPCCC 64.

    Directory of Open Access Journals (Sweden)

    D P Singh

    Full Text Available This study deals with anilofos tolerance and its mineralization by the common rice field cyanobacterium Synechocystis sp. strain PUPCCC 64. The organism tolerated anilofos up to 25 mg L(-1. The herbicide caused inhibitory effects on photosynthetic pigments of the test organism in a dose-dependent manner. The organism exhibited 60, 89, 96, 85 and 79% decrease in chlorophyll a, carotenoids, phycocyanin, allophycocyanin and phycoerythrin, respectively, in 20 mg L(-1 anilofos on day six. Activities of superoxide dismutase, catalase and peroxidase increased by 1.04 to 1.80 times over control cultures in presence of 20 mg L(-1 anilofos. Glutathione content decreased by 26% while proline content was unaffected by 20 mg L(-1 anilofos. The test organism showed intracellular uptake and metabolized the herbicide. Uptake of herbicide by test organism was fast during initial six hours followed by slow uptake until 120 hours. The organism exhibited maximum anilofos removal at 100 mg protein L(-1, pH 8.0 and 30°C. Its growth in phosphate deficient basal medium in the presence of anilofos (2.5 mg L(-1 indicated that herbicide was used by the strain PUPCCC 64 as a source of phosphate.

  3. Dinitrogen fixation is restricted to the terminal heterocysts in the invasive cyanobacterium Cylindrospermopsis raciborskii CS-505.

    Directory of Open Access Journals (Sweden)

    Álvaro M Plominsky

    Full Text Available The toxin producing nitrogen-fixing heterocystous freshwater cyanobacterium Cylindrospermopsis raciborskii recently radiated from its endemic tropical environment into sub-tropical and temperate regions, a radiation likely to be favored by its ability to fix dinitrogen (diazotrophy. Although most heterocystous cyanobacteria differentiate regularly spaced intercalary heterocysts along their trichomes when combined nitrogen sources are depleted, C. raciborskii differentiates only two terminal heterocysts (one at each trichome end that can reach >100 vegetative cells each. Here we investigated whether these terminal heterocysts are the exclusive sites for dinitrogen fixation in C. raciborskii. The highest nitrogenase activity and NifH biosynthesis (western-blot were restricted to the light phase of a 12/12 light/dark cycle. Separation of heterocysts and vegetative cells (sonication and two-phase aqueous polymer partitioning demonstrated that the terminal heterocysts are the sole sites for nifH expression (RT-PCR and NifH biosynthesis. The latter finding was verified by the exclusive localization of nitrogenase in the terminal heterocysts of intact trichomes (immunogold-transmission electron microscopy and in situ immunofluorescence-light microscopy. These results suggest that the terminal heterocysts provide the combined nitrogen required by the often long trichomes (>100 vegetative cells. Our data also suggests that the terminal-heterocyst phenotype in C. raciborskii may be explained by the lack of a patL ortholog. These data help identify mechanisms by which C. raciborskii and other terminal heterocyst-forming cyanobacteria successfully inhabit environments depleted in combined nitrogen.

  4. Toxin release in response to oxidative stress and programmed cell death in the cyanobacterium Microcystis aeruginosa

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Cliff [Smithsonian Marine Station at Fort Pierce, 701 Seaway Drive, Ft. Pierce, FL 34949 (United States)]. E-mail: Ross@sms.si.edu; Santiago-Vazquez, Lory [Department of Chemistry and Biochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431 (United States); Paul, Valerie [Smithsonian Marine Station at Fort Pierce, 701 Seaway Drive, Ft. Pierce, FL 34949 (United States)

    2006-06-10

    An unprecedented bloom of the cyanobacterium Microcystis aeruginosa Kuetz. occurred in the St. Lucie Estuary, FL in the summer of 2005. Samples were analyzed for toxicity by ELISA and by use of the polymerase chain reaction (PCR) with specific oligonucleotide primers for the mcyB gene that has previously been correlated with the biosynthesis of toxic microcystins. Despite the fact that secreted toxin levels were relatively low in dense natural assemblages (3.5 {mu}g l{sup -1}), detectable toxin levels increased by 90% when M. aeruginosa was stressed by an increase in salinity, physical injury, application of the chemical herbicide paraquat, or UV irradiation. The application of the same stressors caused a three-fold increase in the production of H{sub 2}O{sub 2} when compared to non-stressed cells. The application of micromolar concentrations of H{sub 2}O{sub 2} induced programmed cell death (PCD) as measured by a caspase protease assay. Catalase was capable of inhibiting PCD, implicating H{sub 2}O{sub 2} as the inducing oxidative species. Our results indicate that physical stressors induce oxidative stress, which results in PCD and a concomitant release of toxin into the surrounding media. Remediation strategies that induce cellular stress should be approached with caution since these protocols are capable of releasing elevated levels of microcystins into the environment.

  5. Growth enhancing effect of exogenous glycine and characterization of its uptake in halotolerant cyanobacterium Aphanothece halophytica.

    Science.gov (United States)

    Bualuang, Aporn; Incharoensakdi, Aran

    2015-02-01

    Alkaliphilic halotolerant cyanobacterium Aphanothece halophytica showed optimal growth in the medium containing 0.5 M NaCl. The increase of exogenously added glycine to the medium up to 10 mM significantly promoted cell growth under both normal (0.5 M NaCl) and salt stress (2.0 M NaCl) conditions. Salt stress imposed by either 2.0 or 3.0 M NaCl retarded cell growth; however, exogenously added glycine at 10 mM concentration to salt-stress medium resulted in the reduction of growth inhibition particularly under 3.0 M NaCl condition. The uptake of glycine by intact A. halophytica was shown to exhibit saturation kinetics with an apparent K s of 160 μM and V max of 3.9 nmol/min/mg protein. The optimal pH for glycine uptake was at pH 8.0. The uptake activity was decreased in the presence of high concentration of NaCl. Both metabolic inhibitors and ionophores decreased glycine uptake in A. halophytica suggesting an energy-dependent glycine uptake. Several neutral amino acids showed considerable inhibition of glycine uptake with higher than 50 % inhibition observed with serine, cysteine and alanine whereas acidic, basic and aromatic amino acids showed only slight inhibition of glycine uptake.

  6. Metabolomic approach to optimizing and evaluating antibiotic treatment in the axenic culture of cyanobacterium Nostoc flagelliforme.

    Science.gov (United States)

    Han, Pei-pei; Jia, Shi-ru; Sun, Ying; Tan, Zhi-lei; Zhong, Cheng; Dai, Yu-jie; Tan, Ning; Shen, Shi-gang

    2014-09-01

    The application of antibiotic treatment with assistance of metabolomic approach in axenic isolation of cyanobacterium Nostoc flagelliforme was investigated. Seven antibiotics were tested at 1-100 mg L(-1), and order of tolerance of N. flagelliforme cells was obtained as kanamycin > ampicillin, tetracycline > chloromycetin, gentamicin > spectinomycin > streptomycin. Four antibiotics were selected based on differences in antibiotic sensitivity of N. flagelliforme and associated bacteria, and their effects on N. flagelliforme cells including the changes of metabolic activity with antibiotics and the metabolic recovery after removal were assessed by a metabolomic approach based on gas chromatography-mass spectrometry combined with multivariate analysis. The results showed that antibiotic treatment had affected cell metabolism as antibiotics treated cells were metabolically distinct from control cells, but the metabolic activity would be recovered via eliminating antibiotics and the sequence of metabolic recovery time needed was spectinomycin, gentamicin > ampicillin > kanamycin. The procedures of antibiotic treatment have been accordingly optimized as a consecutive treatment starting with spectinomycin, then gentamicin, ampicillin and lastly kanamycin, and proved to be highly effective in eliminating the bacteria as examined by agar plating method and light microscope examination. Our work presented a strategy to obtain axenic culture of N. flagelliforme and provided a method for evaluating and optimizing cyanobacteria purification process through diagnosing target species cellular state.

  7. Structural Elucidation and Molecular Docking of a Novel Antibiotic Compound from Cyanobacterium Nostoc sp. MGL001

    Science.gov (United States)

    Niveshika; Verma, Ekta; Mishra, Arun K.; Singh, Angad K.; Singh, Vinay K.

    2016-01-01

    Cyanobacteria are rich source of array of bioactive compounds. The present study reports a novel antibacterial bioactive compound purified from cyanobacterium Nostoc sp. MGL001 using various chromatographic techniques viz. thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Further characterization was done using electrospray ionization mass spectroscopy (ESIMS) and nuclear magnetic resonance (NMR) and predicted structure of bioactive compound was 9-Ethyliminomethyl-12-(morpholin - 4 - ylmethoxy) -5, 8, 13, 16–tetraaza–hexacene - 2, 3 dicarboxylic acid (EMTAHDCA). Structure of EMTAHDCA clearly indicated that it is a novel compound that was not reported in literature or natural product database. The compound exhibited growth inhibiting effects mainly against the gram negative bacterial strains and produced maximum zone of inhibition at 150 μg/mL concentration. The compound was evaluated through in silico studies for its ability to bind 30S ribosomal fragment (PDB ID: 1YRJ, 1MWL, 1J7T, and 1LC4) and OmpF porin protein (4GCP, 4GCQ, and 4GCS) which are the common targets of various antibiotic drugs. Comparative molecular docking study revealed that EMTAHDCA has strong binding affinity for these selected targets in comparison to a number of most commonly used antibiotics. The ability of EMTAHDCA to bind the active sites on the proteins and 30S ribosomal fragments where the antibiotic drugs generally bind indicated that it is functionally similar to the commercially available drugs. PMID:27965634

  8. Anti-MRSA-acting carbamidocyclophanes H-L from the Vietnamese cyanobacterium Nostoc sp. CAVN2.

    Science.gov (United States)

    Preisitsch, Michael; Harmrolfs, Kirsten; Pham, Hang T L; Heiden, Stefan E; Füssel, Anna; Wiesner, Christoph; Pretsch, Alexander; Swiatecka-Hagenbruch, Monika; Niedermeyer, Timo H J; Müller, Rolf; Mundt, Sabine

    2015-03-01

    The methanol extract of the Vietnamese freshwater cyanobacterium Nostoc sp. CAVN2 exhibited cytotoxic effects against MCF-7 and 5637 cancer cell lines as well as against nontumorigenic FL and HaCaT cells and was active against methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pneumoniae. High-resolution mass spectrometric analysis indicated the presence of over 60 putative cyclophane-like compounds in an antimicrobially active methanol extract fraction. A paracyclophanes-focusing extraction and separation methodology led to the isolation of 5 new carbamidocyclophanes (1-5) and 11 known paracyclophanes (6-16). The structures and their stereochemical configurations were elucidated by a combination of spectrometric and spectroscopic methods including HRMS, 1D and 2D NMR analyses and detailed comparative CD analysis. The newly described monocarbamoylated [7.7]paracyclophanes (1, 2, 4 and 5) differ by a varying degree of chlorination in the side chains. Carbamidocyclophane J (3) is the very first reported carbamidocyclophane bearing a single halogenation in both butyl residues. Based on previous studies a detailed phylogenetic examination of cyclophane-producing cyanobacteria was carried out. The biological evaluation of 1-16 against various clinical pathogens highlighted a remarkable antimicrobial activity against MRSA with MICs of 0.1-1.0 μM, and indicated that the level of antibacterial activity is related to the presence of carbamoyl moieties.

  9. Structural elucidation and molecular docking of a novel antibiotic compound from cyanobacterium Nostoc sp. MGL001

    Directory of Open Access Journals (Sweden)

    Niveshika No Name

    2016-11-01

    Full Text Available Cyanobacteria are rich source of array of bioactive compounds. The present study reports a novel antibacterial bioactive compound purified from cyanobacterium Nostoc sp. MGL001 using various chromatographic techniques viz. thin layer chromatography (TLC and high performance liquid chromatography (HPLC. Further characterization was done using electrospray ionisation mass spectroscopy (ESIMS and nuclear magnetic resonance (NMR and predicted structure of bioactive compound was 9-Ethyliminomethyl-12-(morpholin - 4 - ylmethoxy -5, 8, 13, 16 – tetraaza – hexacene - 2, 3 dicarboxylic acid (EMTAHDCA. Structure of EMTAHDCA clearly indicated that it is a novel compound that was not reported in literature or natural product database. The compound exhibited growth inhibiting effects mainly against the gram negative bacterial strains and produced maximum zone of inhibition at 150 μg/mL concentration. The compound was evaluated through in silico studies for its ability to bind 30S ribosomal fragment (PDB ID: 1YRJ, 1MWL, 1J7T and 1LC4 and OmpF porin protein (4GCP, 4GCQ and 4GCS which are the common targets of various antibiotic drugs. Comparative molecular docking study revealed that EMTAHDCA has strong binding affinity for these selected targets in comparison to a number of most commonly used antibiotics. The ability of EMTAHDCA to bind the active sites on the proteins and 30S ribosomal fragments where the antibiotic drugs generally bind indicated that it is functionally similar to the commercially available drugs.

  10. Nostopeptolide plays a governing role during cellular differentiation of the symbiotic cyanobacterium Nostoc punctiforme.

    Science.gov (United States)

    Liaimer, Anton; Helfrich, Eric J N; Hinrichs, Katrin; Guljamow, Arthur; Ishida, Keishi; Hertweck, Christian; Dittmann, Elke

    2015-02-10

    Nostoc punctiforme is a versatile cyanobacterium that can live either independently or in symbiosis with plants from distinct taxa. Chemical cues from plants and N. punctiforme were shown to stimulate or repress, respectively, the differentiation of infectious motile filaments known as hormogonia. We have used a polyketide synthase mutant that accumulates an elevated amount of hormogonia as a tool to understand the effect of secondary metabolites on cellular differentiation of N. punctiforme. Applying MALDI imaging to illustrate the reprogramming of the secondary metabolome, nostopeptolides were identified as the predominant difference in the pks2(-) mutant secretome. Subsequent differentiation assays and visualization of cell-type-specific expression of nostopeptolides via a transcriptional reporter strain provided evidence for a multifaceted role of nostopeptolides, either as an autogenic hormogonium-repressing factor or as a chemoattractant, depending on its extracellular concentration. Although nostopeptolide is constitutively expressed in the free-living state, secreted levels dynamically change before, during, and after the hormogonium differentiation phase. The metabolite was found to be strictly down-regulated in symbiosis with Gunnera manicata and Blasia pusilla, whereas other metabolites are up-regulated, as demonstrated via MALDI imaging, suggesting plants modulate the fine-balanced cross-talk network of secondary metabolites within N. punctiforme.

  11. Merocyclophanes C and D from the Cultured Freshwater Cyanobacterium Nostoc sp. (UIC 10110).

    Science.gov (United States)

    May, Daniel S; Chen, Wei-Lun; Lantvit, Daniel D; Zhang, Xiaoli; Krunic, Aleksej; Burdette, Joanna E; Eustaquio, Alessandra; Orjala, Jimmy

    2017-04-28

    Merocyclophanes C and D (1 and 2) were isolated from the cell extract of the cultured cyanobacterium UIC 10110. The structures were determined by one-dimensional nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry and confirmed by 2D NMR techniques. The absolute configurations were determined using electronic circular dichroism spectroscopy. Merocyclophanes C and D represent the first known analogues of the merocyclophane core structure, a recently discovered scaffold of [7,7] paracyclophanes characterized by an α-branched methyl at C-1/C-14; 1 and 2 showed antiproliferative activity against the MDA-MB-435 cell line with IC50 values of 1.6 and 0.9 μM, respectively. Partial 16S analysis determined UIC 10110 to be a Nostoc sp., and it was found to clade with UIC 10062 Nostoc sp., the only other strain known to produce merocyclophanes. The genome of UIC 10110 was sequenced, and a biosynthetic gene cluster was identified that is proposed to encode type I and type III polyketide synthases that are potentially responsible for production of the merocyclophanes; however, further experiments will be required to verify the true function of the gene cluster. The gene cluster provides a genetic basis for the observed structural differences of the [7,7] paracyclophane core structures.

  12. Photosynthetic performance of a helical tubular photobioreactor incorporating the cyanobacterium Spirulina platensis

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Yoshitomo; Hall, D.O. [Univ. of London (United Kingdom); Nouee, J. De La [Univ. Laval, Quebec City, Quebec (Canada). Dept. of Food Science and Technology

    1995-07-20

    The photosynthetic performance of a helical tubular photobioreactor (``Biocoil``), incorporating the filamentous cyanobacterium Spirulina platensis, was investigated. The photobioreactor was constructed in a cylindrical shape with a 0.25-m{sup 2} basal area and a photostage comprising 60 m of transparent PVC tubing of 1.6-cm inner diameter. The inner surface of the cylinder was illuminated with cool white fluorescent lamps; the energy input of photosynthetically active radiation into the photobioreactor was 2,920 kJ per day. An air-lift system incorporating 4% CO{sub 2} was used to circulate the growth medium in the tubing. The maximum productivity achieved in batch culture was 7.18 g dry biomass per day which corresponded to a photosynthetic (PAR) efficiency of 5.45%. The CO{sub 2} was efficiently removed from the gaseous stream; monitoring the CO{sub 2} in the outlet and inlet gas streams showed a 70% removal of CO{sub 2} from the inlet gas over an 8-h period with almost maximum growth rate.

  13. Hydrogen sulfide can inhibit and enhance oxygenic photosynthesis in a cyanobacterium from sulfidic springs.

    Science.gov (United States)

    Klatt, Judith M; Haas, Sebastian; Yilmaz, Pelin; de Beer, Dirk; Polerecky, Lubos

    2015-09-01

    We used microsensors to investigate the combinatory effect of hydrogen sulfide (H2 S) and light on oxygenic photosynthesis in biofilms formed by a cyanobacterium from sulfidic springs. We found that photosynthesis was both positively and negatively affected by H2 S: (i) H2 S accelerated the recovery of photosynthesis after prolonged exposure to darkness and anoxia. We suggest that this is possibly due to regulatory effects of H2 S on photosystem I components and/or on the Calvin cycle. (ii) H2 S concentrations of up to 210 μM temporarily enhanced the photosynthetic rates at low irradiance. Modelling showed that this enhancement is plausibly based on changes in the light-harvesting efficiency. (iii) Above a certain light-dependent concentration threshold H2 S also acted as an inhibitor. Intriguingly, this inhibition was not instant but occurred only after a specific time interval that decreased with increasing light intensity. That photosynthesis is most sensitive to inhibition at high light intensities suggests that H2 S inactivates an intermediate of the oxygen evolving complex that accumulates with increasing light intensity. We discuss the implications of these three effects of H2 S in the context of cyanobacterial photosynthesis under conditions with diurnally fluctuating light and H2 S concentrations, such as those occurring in microbial mats and biofilms. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  14. Accelerating of Pink Pigment Excretion from Cyanobacterium Oscillatoria by Co-Cultivation with Anabaena

    Directory of Open Access Journals (Sweden)

    DWI SUSILANINGSIH

    2007-03-01

    Full Text Available The freshwater cyanobacterium Oscillatoria BTCC/A 0004 excretes pink pigment containing lipoproteins with molecular weights of about 10 kDa. This pigment has surfactant properties with strong emulsification activity toward several hydrocarbons. This extracellular metabolite was suspected as toxin or allelochemical in their habitat. In this study, I investigated the effect of co-cultivation of Oscillatoria with Anabaena variabilis on the pigment excretion to explore the physiological roles of this pigment in its natural environment. The dead or viable cells and medium of A. variabilis were added into Oscillatoria cultures. Results showed that co-cultivation of free viable cells of A. variabilis enhanced the excretion of pigment without effect on the cell growth. Co-cultivation with viable cells in separated method and dead cells did not influenced the pigment production. The addition of A. variabilis medium was slightly increased the excretion of the pigment. Those results indicated that direct contact with A. variabilis caused Oscillatoria released a certain signaling compound.

  15. Effect of growth conditions on the hydrogen production with cyanobacterium Anabaena sp. strain CH3

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Pei-Chung [Institute of Clinical Nutrition, Hungkuang University, 34, Chung-Chie Road, Sha Lu, Taichung 433 (China); Fan, Shin-Huei; Chiang, Char-Lin; Lee, Chi-Mei [Department of Environmental Engineering, National Chung Hsing University, 250, Kuo-Kuang Road, Taichung 402 (China)

    2008-03-15

    Cyanobacteria could use sugars as carbon source and reductant to produce hydrogen by nitrogenase. However, oxygen is also produced during photosynthesis and it is an inhibitor of the enzyme nitrogenase. Filamentous cyanobacterium Anabaena sp. CH{sub 3} could use sugars as substrate to produce molecular hydrogen anaerobically. The production activity was dependent on growth phases. It was found that the cells at sub-stage of late-log phase had better ability to produce hydrogen than at log phase. In such case, oxygen content was too low to be detected to inhibit hydrogen production. Among different kinds of sugar, fructose and glucose had the best performance for producing hydrogen. Hydrogen could be accumulated to 0.6 mmol (in 40 ml head space) in 100 h from 1000 ppm fructose. Increasing light intensities from 65 to 130{mu}molm{sup -2}s{sup -1} would enhance hydrogen production to 0.8 mmol. Under illumination of 130{mu}molm{sup -2}s{sup -1} and 2000 ppm fructose, 1.7 mmol of hydrogen could be accumulated. When fructose content was higher than 2000 ppm, cells could not produce more hydrogen at all. (author)

  16. Paired cloning vectors for complementation of mutations in the cyanobacterium Anabaena sp. strain PCC 7120

    Energy Technology Data Exchange (ETDEWEB)

    Wolk, C. Peter Wolk [Michigan State University, East Lansing; Fan, Qing [Northwestern University, Evanston; Zhou, Ruanbao [Anhui Normal University, People' s Republic of China; Huang, Guocun [University of Texas Southwestern Medical; Lechno-Yossef, Sigal [Michigan State University, East Lansing; Kuritz, Tanya [ORNL; Wojciuch, Elizabeth [Michigan State University, East Lansing

    2007-01-01

    The clones generated in a sequencing project represent a resource for subsequent analysis of the organism whose genome has been sequenced. We describe an interrelated group of cloning vectors that either integrate into the genome or replicate, and that enhance the utility, for developmental and other studies, of the clones used to determine the genomic sequence of the cyanobacterium, Anabaena sp. strain PCC 7120. One integrating vector is a mobilizable BAC vector that was used both to generate bridging clones and to complement transposon mutations. Upon addition of a cassette that permits mobilization and selection, pUC-based sequencing clones can also integrate into the genome and thereupon complement transposon mutations. The replicating vectors are based on cyanobacterial plasmid pDU1, whose sequence we report, and on broad-host-range plasmid RSF1010. The RSF1010- and pDU1-based vectors provide the opportunity to express different genes from either cell-type-specific or -generalist promoters, simultaneously from different plasmids in the same cyanobacterial cells. We show that pDU1 ORF4 and its upstream region play an essential role in the replication and copy number of pDU1, and that ORFs alr2887 and alr3546 (hetF{sub A}) of Anabaena sp. are required specifically for fixation of dinitrogen under oxic conditions.

  17. Fluorapatite as Inorganic Phosphate Source for the Cyanobacterium Anabaena PCC 7120

    Science.gov (United States)

    Schaperdoth, I.; Brantley, S.

    2003-12-01

    We investigated the hypothesis that the cyanobacterium Anabaena PCC 7120 is able to use fluorapatite (FAP) as sole phosphate source for growth. In the experimental setup the dissolution of FAP was tested in a phosphate free growth medium in the presence and absence of the Anabaena, as well as the cell free supernatant of an Anabaena culture. The results were compared with that of an Anabaena culture grown without fluorapatite. Parameters measured were pH, dissolved P and Ca, as well as cell density. The FAP grains were analyzed using SEM and XPS. Additionally, the differential expression of secreted proteins in cultures with and without dissolved phosphate was examined. P-limited Anabaena cultures tend to aggregate and in the presence of FAP the cells attached themselves to the mineral grains. The cultures benefit from the presence of FAP. The cells have a very effective P-uptake system that is able to take up dissolved phosphate very efficiently and draw the concentrations down to very low levels. Furthermore, the SEM analysis of FAP showed an etching of the mineral grains in the samples from the Anabaena cultures. The mechanism of apatite dissolution with and without Anabaena will be discussed in terms of these experimental observations.

  18. Multiple modes of iron uptake by the filamentous, siderophore-producing cyanobacterium, Anabaena sp. PCC 7120.

    Science.gov (United States)

    Rudolf, Mareike; Kranzler, Chana; Lis, Hagar; Margulis, Ketty; Stevanovic, Mara; Keren, Nir; Schleiff, Enrico

    2015-08-01

    Iron is a member of a small group of nutrients that limits aquatic primary production. Mechanisms for utilizing iron have to be efficient and adapted according to the ecological niche. In respect to iron acquisition cyanobacteria, prokaryotic oxygen evolving photosynthetic organisms can be divided into siderophore- and non-siderophore-producing strains. The results presented in this paper suggest that the situation is far more complex. To understand the bioavailability of different iron substrates and the advantages of various uptake strategies, we examined iron uptake mechanisms in the siderophore-producing cyanobacterium Anabaena sp. PCC 7120. Comparison of the uptake of iron complexed with exogenous (desferrioxamine B, DFB) or to self-secreted (schizokinen) siderophores by Anabaena sp. revealed that uptake of the endogenous produced siderophore complexed to iron is more efficient. In addition, Anabaena sp. is able to take up dissolved, ferric iron hydroxide species (Fe') via a reductive mechanism. Thus, Anabaena sp. exhibits both, siderophore- and non-siderophore-mediated iron uptake. While assimilation of Fe' and FeDFB are not induced by iron starvation, FeSchizokinen uptake rates increase with increasing iron starvation. Consequently, we suggest that Fe' reduction and uptake is advantageous for low-density cultures, while at higher densities siderophore uptake is preferred.

  19. Functional Diversity of Transcriptional Regulators in the Cyanobacterium Synechocystis sp. PCC 6803

    Science.gov (United States)

    Shi, Mengliang; Zhang, Xiaoqing; Pei, Guangsheng; Chen, Lei; Zhang, Weiwen

    2017-01-01

    Functions of transcriptional regulators (TRs) are still poorly understood in the model cyanobacterium Synechocystis sp. PCC 6803. To address the issue, we constructed knockout mutants for 32 putative TR-encoding genes of Synechocystis, and comparatively analyzed their phenotypes under autotrophic growth condition and metabolic profiles using liquid chromatography-mass spectrometry-based metabolomics. The results showed that only four mutants of TR genes, sll1872 (lytR), slr0741 (phoU), slr0395 (ntcB), and slr1871 (pirR), showed differential growth patterns in BG11 medium when compared with the wild type; however, in spite of no growth difference observed for the remaining TR mutants, metabolomic profiling showed that they were different at the metabolite level, suggesting significant functional diversity of TRs in Synechocystis. In addition, an integrative metabolomic and gene families’ analysis of all TR mutants led to the identification of five pairs of TR genes that each shared close relationship in both gene families and metabolomic clustering trees, suggesting possible conserved functions of these TRs during evolution. Moreover, more than a dozen pairs of TR genes with different origin and evolution were found with similar metabolomic profiles, suggesting a possible functional convergence of the TRs during genome evolution. Finally, a protein–protein network analysis was performed to predict regulatory targets of TRs, allowing inference of possible regulatory gene targets for 4 out of five pairs of TRs. This study provided new insights into the regulatory functions and evolution of TR genes in Synechocystis. PMID:28270809

  20. Fur-type transcriptional repressors and metal homeostasis in the cyanobacterium Synechococcus sp. PCC 7002

    Directory of Open Access Journals (Sweden)

    Marcus eLudwig

    2015-10-01

    Full Text Available Metal homeostasis is a crucial cellular function for nearly all organisms. Some heavy metals (e.g. Fe, Zn, Co, Mo are essential because they serve as cofactors for enzymes or metalloproteins, and chlorophototrophs such as cyanobacteria have an especially high demand for iron. At excessive levels, however, metals become toxic to cyanobacteria. Therefore, a tight control mechanism is essential for metal homeostasis. Metal homeostasis in microorganisms comprises two elements: metal acquisition from the environment and detoxification or excretion of excess metal ions. Different families of metal-sensing regulators exist in cyanobacteria and each addresses a more or less specific set of target genes. In this study the regulons of three Fur-type and two ArsR-SmtB-type regulators were investigated in a comparative approach in the cyanobacterium Synechococcus sp. PCC 7002. One Fur-type regulator controls genes for iron acquisition (Fur; one controls genes for zinc acquisition (Zur; and the third controls two genes involved in oxidative stress (Per. Compared to other well-investigated cyanobacterial strains, however, the set of target genes for each regulator is relatively small. Target genes for the two ArsR-SmtB transcriptional repressors (SmtB (SYNPCC7002_A2564 and SYNPCC7002_A0590; ArsR are involved in zinc homeostasis in addition to Zur. Their target genes, however, are less specific for zinc and point to roles in a broader heavy metal detoxification response.

  1. Molecular genetic and chemotaxonomic characterization of the terrestrial cyanobacterium Nostoc commune and its neighboring species.

    Science.gov (United States)

    Arima, Hiromi; Horiguchi, Noriomi; Takaichi, Shinichi; Kofuji, Rumiko; Ishida, Ken-Ichiro; Wada, Keishiro; Sakamoto, Toshio

    2012-01-01

    The phylogeny of the terrestrial cyanobacterium Nostoc commune and its neighboring Nostoc species was studied using molecular genetic and chemotaxonomic approaches. At least eight genotypes of N. commune were characterized by the differences among 16S rRNA gene sequences and the petH gene encoding ferredoxin-NADP⁺ oxidoreductase and by random amplified polymorphic DNA analysis. The genotypes of N. commune were distributed in Japan without regional specificity. The nrtP gene encoding NrtP-type nitrate/nitrite permease was widely distributed in the genus Nostoc, suggesting that the occurrence of the nrtP gene can be one of the characteristic features that separate cyanobacteria into two groups. The wspA gene encoding a 36-kDa water stress protein was only found in N. commune and Nostoc verrucosum, suggesting that these Nostoc species that form massive colonies with extracellular polysaccharides can be exclusively characterized by the occurrence of the wspA gene. Fifteen species of Nostoc and Anabaena were investigated by comparing their carotenoid composition. Three groups with distinct patterns of carotenoids were related to the phylogenic tree constructed on the basis of 16S rRNA sequences. Nostoc commune and Nostoc punctiforme were clustered in one monophyletic group and characterized by the occurrence of nostoxanthin, canthaxanthin, and myxol glycosides.

  2. Glycosylated porphyra-334 and palythine-threonine from the terrestrial cyanobacterium Nostoc commune.

    Science.gov (United States)

    Nazifi, Ehsan; Wada, Naoki; Yamaba, Minami; Asano, Tomoya; Nishiuchi, Takumi; Matsugo, Seiichi; Sakamoto, Toshio

    2013-08-26

    Mycosporine-like amino acids (MAAs) are water-soluble UV-absorbing pigments, and structurally different MAAs have been identified in eukaryotic algae and cyanobacteria. In this study novel glycosylated MAAs were found in the terrestrial cyanobacterium Nostoc commune (N. commune). An MAA with an absorption maximum at 334 nm was identified as a hexose-bound porphyra-334 derivative with a molecular mass of 508 Da. Another MAA with an absorption maximum at 322 nm was identified as a two hexose-bound palythine-threonine derivative with a molecular mass of 612 Da. These purified MAAs have radical scavenging activities in vitro, which suggests multifunctional roles as sunscreens and antioxidants. The 612-Da MAA accounted for approximately 60% of the total MAAs and contributed approximately 20% of the total radical scavenging activities in a water extract, indicating that it is the major water-soluble UV-protectant and radical scavenger component. The hexose-bound porphyra-334 derivative and the glycosylated palythine-threonine derivatives were found in a specific genotype of N. commune, suggesting that glycosylated MAA patterns could be a chemotaxonomic marker for the characterization of the morphologically indistinguishable N. commune. The glycosylation of porphyra-334 and palythine-threonine in N. commune suggests a unique adaptation for terrestrial environments that are drastically fluctuating in comparison to stable aquatic environments.

  3. Sulfonamide inhibition studies of the γ-carbonic anhydrase from the Antarctic cyanobacterium Nostoc commune.

    Science.gov (United States)

    Vullo, Daniela; De Luca, Viviana; Del Prete, Sonia; Carginale, Vincenzo; Scozzafava, Andrea; Capasso, Clemente; Supuran, Claudiu T

    2015-04-15

    A carbonic anhydrase (CA, EC 4.2.1.1) belonging to the γ-class has been cloned, purified and characterized from the Antarctic cyanobacterium Nostoc commune. The enzyme showed a good catalytic activity for the physiologic reaction (hydration of carbon dioxide to bicarbonate and a proton) with the following kinetic parameters, kcat of 9.5×10(5)s(-1) and kcat/KM of 8.3×10(7)M(-1)s(-1), being the γ-CA with the highest catalytic activity described so far. A range of aromatic/heterocyclic sulfonamides and one sulfamate were investigated as inhibitors of the new enzyme, denominated here NcoCA. The best NcoCA inhibitors were some sulfonylated sulfanilamide derivatives possessing elongated molecules, aminobenzolamide, acetazolamide, benzolamide, dorzolamide, brinzolamide and topiramate, which showed inhibition constants in the range of 40.3-92.3nM. As 1,5-bisphosphate carboxylase/oxygenase (RubisCO) and γ-CAs are closely associated in carboxysomes of cyanobacteria for enhancing the affinity of RubisCO for CO2 and the efficiency of photosynthesis, investigation of this new enzyme and its affinity for modulators of its activity may bring new insights in these crucial processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Novel glycosylated mycosporine-like amino acids with radical scavenging activity from the cyanobacterium Nostoc commune.

    Science.gov (United States)

    Matsui, Kei; Nazifi, Ehsan; Kunita, Shinpei; Wada, Naoki; Matsugo, Seiichi; Sakamoto, Toshio

    2011-10-05

    Mycosporine-like amino acids (MAAs) are UV absorbing pigments, and structurally distinct MAAs have been identified in taxonomically diverse organisms. Two novel MAAs were purified from the cyanobacterium Nostoc commune, and their chemical structures were characterized. An MAA with an absorption maximum at 335 nm was identified as a pentose-bound porphyra-334 derivative with a molecular mass of 478 Da. Another identified MAA had double absorption maxima at 312 and 340 nm and a molecular mass of 1,050 Da. Its unique structure consisted of two distinct chromophores of 3-aminocyclohexen-1-one and 1,3-diaminocyclohexen and two pentose and hexose sugars. These MAAs had radical scavenging activity in vitro; the 1050-Da MAA contributed approximately 27% of the total radical scavenging activities in a water extract of N. commune. These results suggest that these glycosylated MAAs have multiple roles as a UV protectant and an antioxidant relevant to anhydrobiosis in N. commune. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Effects of overexpressing photosynthetic carbon flux control enzymes in the cyanobacterium Synechocystis PCC 6803.

    Science.gov (United States)

    Liang, Feiyan; Lindblad, Peter

    2016-11-01

    Synechocystis PCC 6803 is a model unicellular cyanobacterium used in e.g. photosynthesis and CO2 assimilation research. In the present study we examined the effects of overexpressing Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), sedoheptulose 1,7-biphosphatase (SBPase), fructose-bisphosphate aldolase (FBA) and transketolase (TK), confirmed carbon flux control enzymes of the Calvin-Bassham-Benson (CBB) cycle in higher plants, in Synechocystis PCC 6803. Overexpressing RuBisCO, SBPase and FBA resulted in increased in vivo oxygen evolution (maximal 115%), growth rate and biomass accumulation (maximal 52%) under 100μmolphotonsm(-2)s(-1) light condition. Cells overexpressing TK showed a chlorotic phenotype but increased biomass by approximately 42% under 100μmolphotonsm(-2)s(-1) light condition. Under 15μmolphotonsm(-2)s(-1) light condition, cells overexpressing TK showed enhanced in vivo oxygen evolution. This study demonstrates increased growth and biomass accumulation when overexpressing selected enzymes of the CBB cycle. RuBisCO, SBPase, FBA and TK are identified as four potential targets to improve growth and subsequently also yield of valuable products from Synechocystis PCC 6803. Copyright © 2016 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  6. Interplay between gold nanoparticle biosynthesis and metabolic activity of cyanobacterium Synechocystis sp. PCC 6803

    Science.gov (United States)

    Focsan, Monica; Ardelean, Ioan I.; Craciun, Constantin; Astilean, Simion

    2011-12-01

    Many microorganisms have long been known to be able to synthesize nanoparticles either in extracellular media or inside cells but the biochemical mechanisms involved in biomineralization are still poorly understood. In this paper we report the intracellular synthesis of gold nanoparticles (GNPs) by the cyanobacterium Synechocystis sp. PCC 6803 exposed to an aqueous solution of chloroauric acid. We assess the interplay between the biomineralization process and the metabolic activities (i.e. photosynthesis and respiration) of cyanobacteria cells by correlating the GNP synthesis yield with the amount of respiratory and photosynthetic oxygen exchange. The biogenic GNPs are compared in terms of their internalization and biological effects to GNPs synthesized by a standard citrate reduction procedure (cGNPs). The TEM analysis, in conjunction with spectroscopic measurements (i.e. surface plasmon resonance, fluorescence quenching and surface-enhanced Raman scattering, SERS), reveals the localization of biogenic GNPs at the level of intracytoplasmic membranes whereas the pre-formed cGNPs are located at the level of external cellular membrane. Our findings have implications for better understanding the process of biomineralization and assessing the potential risks associated with the accumulation of nanomaterials by various biological systems.

  7. Regulation of the scp Genes in the Cyanobacterium Synechocystis sp. PCC 6803--What is New?

    Science.gov (United States)

    Cheregi, Otilia; Funk, Christiane

    2015-08-12

    In the cyanobacterium Synechocystis sp. PCC 6803 there are five genes encoding small CAB-like (SCP) proteins, which have been shown to be up-regulated under stress. Analyses of the promoter sequences of the scp genes revealed the existence of an NtcA binding motif in two scp genes, scpB and scpE. Binding of NtcA, the key transcriptional regulator during nitrogen stress, to the promoter regions was shown by electrophoretic mobility shift assay. The metabolite 2-oxoglutarate did not increase the affinity of NtcA for binding to the promoters of scpB and scpE. A second motif, the HIP1 palindrome 5' GGCGATCGCC 3', was detected in the upstream regions of scpB and scpC. The transcription factor encoded by sll1130 has been suggested to recognize this motif to regulate heat-responsive genes. Our data suggest that HIP1 is not a regulatory element within the scp genes. Further, the presence of the high light regulatory (HLR1) motif was confirmed in scpB-E, in accordance to their induced transcriptions in cells exposed to high light. The HLR1 motif was newly discovered in eight additional genes.

  8. Type II Toxin-Antitoxin Systems in the Unicellular Cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Kopfmann, Stefan; Roesch, Stefanie K; Hess, Wolfgang R

    2016-07-21

    Bacterial toxin-antitoxin (TA) systems are genetic elements, which are encoded by plasmid as well as chromosomal loci. They mediate plasmid and genomic island maintenance through post-segregational killing mechanisms but may also have milder effects, acting as mobile stress response systems that help certain cells of a population in persisting adverse growth conditions. Very few cyanobacterial TA system have been characterized thus far. In this work, we focus on the cyanobacterium Synechocystis 6803, a widely used model organism. We expand the number of putative Type II TA systems from 36 to 69 plus seven stand-alone components. Forty-seven TA pairs are located on the chromosome and 22 are plasmid-located. Different types of toxins are associated with various antitoxins in a mix and match principle. According to protein domains and experimental data, 81% of all toxins in Synechocystis 6803 likely exhibit RNase activity, suggesting extensive potential for toxicity-related RNA degradation and toxin-mediated transcriptome remodeling. Of particular interest is the Ssr8013-Slr8014 system encoded on plasmid pSYSG, which is part of a larger defense island or the pSYSX system Slr6056-Slr6057, which is linked to a bacterial ubiquitin-like system. Consequently, Synechocystis 6803 is one of the most prolific sources of new information about these genetic elements.

  9. GABA accumulation in response to different nitrogenous compounds in unicellular cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Kanwal, Simab; Khetkorn, Wanthanee; Incharoensakdi, Aran

    2015-01-01

    GABA accumulation and glutamate decarboxylase (GAD) activity, the principal enzyme involved in GABA formation, was investigated in cyanobacterium Synechocystis sp. PCC 6803 wild-type (WT) and gad knockout mutant strains grown in medium containing different nitrogenous compounds. Nitrate was the best nitrogen source for GAD activity and GABA accumulation followed by nitrite, ammonium, and urea. An increase in the accumulation of GABA was observed in WT and mutant cells grown for 24 h in medium supplemented with 0.5 mM putrescine or spermidine with a parallel increase in GAD activity. The mutant could not accumulate GABA at all the conditions tested except when supplemented with putrescine or spermidine, where high GABA levels were observed in both WT and mutant strains. Glutamate supplementation up to 10 mM for 24 h resulted in a significant increase in both GAD activity and GABA content. Overall results suggested that optimization of nitrogen source and nitrogenous compounds supplementation was effective for the enhancement of GABA accumulation in Synechocystis.

  10. Isolation and characterization of a new reported cyanobacterium Leptolyngbya bijugata coproducing odorous geosmin and 2-methylisoborneol.

    Science.gov (United States)

    Wang, Zhongjie; Xiao, Peng; Song, Gaofei; Li, Yeguang; Li, Renhui

    2015-08-01

    The earthy-musty compounds geosmin and 2-methylisoborneol (MIB) produced by cyanobacteria are considered as the main biological causes of off-flavor events, especially in aquatic ecosystems. More than 50 filamentous cyanobacteria species have been documented as geosmin or MIB producers; however, little is known about the species coproducing these two metabolites. In this study, an epiphytic sample was collected from a river in Hubei, China. Three isolated strains (A2, B2, and B4) producing earthy odors were successfully isolated and identified as the cyanobacterium Leptolyngbya bijugata Anagnostidis et Komárek 1988 based on morphology and 16S rDNA sequences. Gas chromatography analysis confirmed that the isolated L. bijugata strains were geosmin and MIB coproducers, with accumulation ranging from 13.6 to 22.4 and 12.3 to 57.5 μg L(-1), respectively. The partial fragments of geosmin and MIB synthesis genes in the L. bijugata strains were cloned and sequenced. Further sequences and phylogenetic analysis indicated the high conservation and a common origin of these genes in cyanobacteria. This study is the first to report and characterize the coproduction of geosmin and MIB by L. bijugata, representing a new source for potential risk of off-flavor events.

  11. Nitrate assimilation gene cluster from the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Frías, J E; Flores, E; Herrero, A

    1997-01-01

    A region of the genome of the filamentous, nitrogen-fixing, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 that contains a cluster of genes involved in nitrate assimilation has been identified. The genes nir, encoding nitrite reductase, and nrtABC, encoding elements of a nitrate permease, have been cloned. Insertion of a gene cassette into the nir-nrtA region impaired expression of narB, the nitrate reductase structural gene which together with nrtD is found downstream from nrtC in the gene cluster. This indicates that the nir-nrtABCD-narB genes are cotranscribed, thus constituting an operon. Expression of the nir operon in strain PCC 7120 is subjected to ammonium-promoted repression and takes place from an NtcA-activated promoter located 460 bp upstream from the start of the nir gene. In the absence of ammonium, cellular levels of the products of the nir operon are higher in the presence of nitrate than in the absence of combined nitrogen.

  12. Characterization of red-shifted phycobilisomes isolated from the chlorophyll f-containing cyanobacterium Halomicronema hongdechloris.

    Science.gov (United States)

    Li, Yaqiong; Lin, Yuankui; Garvey, Christopher J; Birch, Debra; Corkery, Robert W; Loughlin, Patrick C; Scheer, Hugo; Willows, Robert D; Chen, Min

    2016-01-01

    Phycobilisomes are the main light-harvesting protein complexes in cyanobacteria and some algae. It is commonly accepted that these complexes only absorb green and orange light, complementing chlorophyll absorbance. Here, we present a new phycobilisome derived complex that consists only of allophycocyanin core subunits, having red-shifted absorption peaks of 653 and 712 nm. These red-shifted phycobiliprotein complexes were isolated from the chlorophyll f-containing cyanobacterium, Halomicronema hongdechloris, grown under monochromatic 730 nm-wavelength (far-red) light. The 3D model obtained from single particle analysis reveals a double disk assembly of 120-145 Å with two α/β allophycocyanin trimers fitting into the two separated disks. They are significantly smaller than typical phycobilisomes formed from allophycocyanin subunits and core-membrane linker proteins, which fit well with a reduced distance between thylakoid membranes observed from cells grown under far-red light. Spectral analysis of the dissociated and denatured phycobiliprotein complexes grown under both these light conditions shows that the same bilin chromophore, phycocyanobilin, is exclusively used. Our findings show that red-shifted phycobilisomes are required for assisting efficient far-red light harvesting. Their discovery provides new insights into the molecular mechanisms of light harvesting under extreme conditions for photosynthesis, as well as the strategies involved in flexible chromatic acclimation to diverse light conditions.

  13. Envelope structure of Synechococcus sp. WH8113, a nonflagellated swimming cyanobacterium

    Directory of Open Access Journals (Sweden)

    Reese Thomas S

    2001-04-01

    Full Text Available Abstract Background Many bacteria swim by rotating helical flagellar filaments [1]. Waterbury et al. [15] discovered an exception, strains of the cyanobacterium Synechococcus that swim without flagella or visible changes in shape. Other species of cyanobacteria glide on surfaces [2,7]. The hypothesis that Synechococcus might swim using traveling surface waves [6,13] prompted this investigation. Results Using quick-freeze electron microscopy, we have identified a crystalline surface layer that encloses the outer membrane of the motile strain Synechococcus sp. WH8113, the components of which are arranged in a rhomboid lattice. Spicules emerge in profusion from the layer and extend up to 150 nm into the surrounding fluid. These spicules also send extensions inwards to the inner cell membrane where motility is powered by an ion-motive force [17]. Conclusion The envelope structure of Synechococcus sp. WH8113 provides new constraints on its motile mechanism. The spicules are well positioned to transduce energy at the cell membrane into mechanical work at the cell surface. One model is that an unidentified motor embedded in the cell membrane utilizes the spicules as oars to generate a traveling wave external to the surface layer in the manner of ciliated eukaryotes.

  14. Engineered xylose utilization enhances bio-products productivity in the cyanobacterium Synechocystis sp. PCC 6803

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Tai-Chi; Xiong, Wei; Paddock, Troy; Carrieri, Damian; Chang, Ing-Feng; Chiu, Hui-Fen; Ungerer, Justin; Hank Juo, Suh-Hang; Maness, Pin-Ching; Yu, Jianping

    2015-06-12

    Hydrolysis of plant biomass generates a mixture of simple sugars that is particularly rich in glucose and xylose. Fermentation of the released sugars emits CO2 as byproduct due to metabolic inefficiencies. Therefore, the ability of a microbe to simultaneously convert biomass sugars and photosynthetically fix CO2 into target products is very desirable. In this work, the cyanobacterium, Synechocystis 6803, was engineered to grow on xylose in addition to glucose. Both the xylA (xylose isomerase) and xylB (xylulokinase) genes from Escherichia coli were required to confer xylose utilization, but a xylose-specific transporter was not required. Introducing xylAB into an ethylene-producing strain increased the rate of ethylene production in the presence of xylose. Additionally, introduction of xylAB into a glycogen-synthesis mutant enhanced production of keto acids. Moreover, isotopic tracer studies found that nearly half of the carbon in the excreted keto acids was derived from the engineered xylose metabolism, while the remainder was derived from CO2 fixation.

  15. Effect of carbon and nitrogen assimilation on chlorophyll fluorescence emission by the cyanobacterium Anacystis nidulans

    Energy Technology Data Exchange (ETDEWEB)

    Romero, J.M.; Lara, C. (Instituto de Bioquimica Vegetal y Fotosintesis, Univ. de Sevilla y CSIC, Sevilla (ES)); Sivak, M.N. (Dept. of Biochemistry, Michigan State Univ., East Lansing (US))

    1992-01-01

    O{sub 2} evolution and chlorophyll A fluorescence emission have been monitored in intact cells of the cyanobacterium Anacystis nidulans 1402-1 to study the influence of carbon and nitrogen assimilation on the operation of the photosynthetic apparatus. The pattern of fluorescence induction in dark-adapted cyanobacterial cells was different from that of higher plants. Cyanobacteria undergo large, rapid state transitions upon illumination, which lead to marked changes in the fluorescence yield, complicating the estimation of quenching coefficients. The Kautsky effect was not evident, although it could be masked by a state II-state I transition, upon illumination with actinic light. The use of inhibitors of carbon assimilation such as D,L-glyceraldehyde or iodoacetamide allowed us to relate changes in variable fluorescence to active CO{sub 2} fixation. Ammonium, but not nitrate, induced non-photochemical fluorescence quenching, in agreement with a previous report on green algae, indicative of an ammonium-induced state i transition. (au).

  16. Changes in photosynthesis and pigmentation in an agp deletion mutant of the cyanobacterium Synechocystis sp.

    Science.gov (United States)

    Miao, Xiaoling; Wu, Qingyu; Wu, Guifang; Zhao, Nanming

    2003-03-01

    The agp gene encoding ADP-glucose pyrophosphorylase is involved in cyanobacterial glycogen synthesis. By in vitro DNA recombination technology, agp deletion mutant (agp-) of cyanobacterium Synechocystis sp. PCC 6803 was constructed. This mutation led to a complete absence of glycogen biosynthesis. As compared with WT (wild type), a 60% decrease in ratio of the c-phycocyanine/chlorophyll a and no significant change in the carotenoid/chlorophyll a were observed in agp- cells. The agp- mutant had 38% less photosynthetic capacity when grown in light over 600 micromol m(-2) s(-1). Under lower light intensity, the final biomass of the mutant strain was only 1.1 times of that of the WT strain under mixotrophic condition after 6 d culture. Under higher light intensity, however, the final biomass of the WT strain under mixotrophic conditions was 3 times that of the mutant strain after 6 d culture and 1.5 times under photoautotrophic conditions. The results indicate that there is a minimum requirement for glycogen synthesis for normal growth and development in cyanobacteria.

  17. Higher production of C-phycocyanin by nitrogen-free (diazotrophic) cultivation of Nostoc sp. NK and simplified extraction by dark-cold shock.

    Science.gov (United States)

    Lee, Na Kyeong; Oh, Hee-Mock; Kim, Hee-Sik; Ahn, Chi-Yong

    2017-03-01

    Nostoc sp. NK (KCTC 12772BP) was isolated and cultivated in a BG11 medium and a nitrate-free BG11 medium (BG110). To enhance C-phycocyanin (C-PC) content in the cells, different fluorescent lamps (white, plant, and red) were used as light sources for complementary chromatic adaptation (CCA). The maximum biomass productivity was 0.42g/L/d and 0.32g/L/d under BG11 and BG110 conditions, respectively. The maximum C-PC contents were 8.4% (w/w) under white lamps, 13.6% (w/w) under plant lamps, and 18% (w/w) under BG110 and the red light condition. The maximum C-PC productivity was 57.4mg/L/d in BG110 under the red lamp condition. These results indicate that a higher C-PC content could be obtained under a diazotrophic condition and a CCA reaction. The C-PC could be released naturally from cells without any extraction processes, when Nostoc sp. NK was cultivated in the BG110 medium with CO2 aeration and put in dark conditions at 5°C. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Organic matter inoculated with diazotrophic bacterium Beijerinckia indica and Cunninghamella elegans fungus containing chitosan on banana “Williams” in field

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    Newton Pereira Stamford

    2017-01-01

    Full Text Available The production of biofertilizers from rocks increases nutrients for plant nutrition without environmental pollution. The aim of this study was to evaluate the effectiveness of biofertilizers from phosphate and potassium rocks mixed with organic matter (earthworm compound inoculated with free living diazotrophic bacteria (NFB 10001 and Cunninghamella elegans (fungus with chitosan on yield, characteristics, and nutrient uptake of banana (cv. Williams, and attributes of a Red Yellow Argisoil of the rainforest Zone of Pernambuco, Brazil. The experimental design included two biofertilizers: (a PK rock biofertilizers plus organic matter (NPKB and (b bioprotector (NPKP applied at 50, 100 and 150% of the recommended rate for banana, which were compared with soluble mineral fertilizers (NPKF applied at the recommended rate, and earthworm compound (20 ton ha-1. The best results of the plant parameters were obtained with NPKB and NPKP applied at the highest rates (150% RR. A normal yield was produced when NPKB and NPKP were applied at the highest rates and NPKF at the recommended rate. The available P and K in the soil showed a significant fertilization effect, especially when NPKB and NPKP were applied at the highest rates. The biofertilizer and bioprotector may be alternatives to mineral soluble fertilizers.

  19. The success of the cyanobacterium Cylindrospermopsis raciborskii in freshwaters is enhanced by the combined effects of light intensity and temperature

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    Sylvia Bonilla

    2016-06-01

    Full Text Available Toxic cyanobacterial blooms in freshwaters are thought to be a consequence of the combined effects of anthropogenic eutrophication and climate change. It is expected that climate change will affect water mixing regimes that alter the water transparency and ultimately the light environment for phytoplankton. Blooms of the potentially toxic cyanobacterium Cylindrospermopsis raciborskii are expanding from tropical towards temperate regions. Several hypotheses have been proposed to explain this expansion, including an increase in water temperature due to climate change and the high phenotypic plasticity of the species that allows it to exploit different light environments. We performed an analysis based on eight lakes in tropical, subtropical and temperate regions to examine the distribution and abundance of C. raciborskii in relation to water temperature and transparency. We then conducted a series of short-term factorial experiments that combined three temperatures and two light intensity levels using C. raciborskii cultures alone and in interaction with another cyanobacterium to identify its growth capacity. Our results from the field, in contrast to predictions, showed no differences in dominance (>40% to the total biovolume of C. raciborskii between climate regions. C. raciborskii was able to dominate the phytoplankton in a wide range of light environments (euphotic zone = 1.5 to 5 m, euphotic zone/mixing zone ratio <0.5 to >1.5. Moreover, C. raciborskii was capable of dominating the phytoplankton at low temperatures (<15°C. Our experimental results showed that C. raciborskii growing in interaction was enhanced by the increase of the temperature and light intensity. C. raciborskii growth in high light intensities and at a wide range of temperatures, suggests that any advantage that this species may derive from climate change that favors its dominance in the phytoplankton is likely due to changes in the light environment rather than changes in

  20. Characterization of three putative xylulose 5-phosphate/fructose 6-phosphate phosphoketolases in the cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Moriyama, Takashi; Tajima, Naoyuki; Sekine, Kohsuke; Sato, Naoki

    2015-01-01

    Xylulose 5-phosphate/fructose 6-phosphate phosphoketolase (Xfp) is a key enzyme in the central carbohydrate metabolism in heterofermentative bacteria, in which enzymatic property of Xfps is well characterized. This is not the case in other microbes. The cyanobacterium Anabaena sp. PCC 7120 possesses three putative genes encoding Xfp, all1483, all2567, and alr1850. We purified three putative Xfps as recombinant proteins. The results of gel filtration indicated that these proteins form homomultimer complex. All1483 and All2567 showed phosphoketolase activity, whereas Alr1850 did not show the activity. Kinetic analyses demonstrated that substrates, fructose 6-phosphate and inorganic phosphate, are cooperatively bound to enzymes positively and negatively, respectively.

  1. The biosynthetic pathway for myxol-2' fucoside (myxoxanthophyll) in the cyanobacterium Synechococcus sp. strain PCC 7002.

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    Graham, Joel E; Bryant, Donald A

    2009-05-01

    Synechococcus sp. strain PCC 7002 produces a variety of carotenoids, which comprise predominantly dicylic beta-carotene and two dicyclic xanthophylls, zeaxanthin and synechoxanthin. However, this cyanobacterium also produces a monocyclic myxoxanthophyll, which was identified as myxol-2' fucoside. Compared to the carotenoid glycosides produced by diverse microorganisms, cyanobacterial myxoxanthophyll and closely related compounds are unusual because they are glycosylated on the 2'-OH rather than on the 1'-OH position of the psi end of the molecule. In this study, the genes encoding two enzymes that modify the psi end of myxoxanthophyll in Synechococcus sp. strain PCC 7002 were identified. Mutational and biochemical studies showed that open reading frame SynPCC7002_A2032, renamed cruF, encodes a 1',2'-hydroxylase [corrected] and that open reading frame SynPCC7002_A2031, renamed cruG, encodes a 2'-O-glycosyltransferase. The enzymatic activity of CruF was verified by chemical characterization of the carotenoid products synthesized when cruF was expressed in a lycopene-producing strain of Escherichia coli. Database searches showed that homologs of cruF and cruG occur in the genomes of all sequenced cyanobacterial strains that are known to produce myxol or the acylic xanthophyll oscillaxanthin. The genomes of many other bacteria that produce hydroxylated carotenoids but do not contain crtC homologs also contain cruF orthologs. Based upon observable intermediates, a complete biosynthetic pathway for myxoxanthophyll is proposed. This study expands the suite of enzymes available for metabolic engineering of carotenoid biosynthetic pathways for biotechnological applications.

  2. Radiation characteristics and effective optical properties of dumbbell-shaped cyanobacterium Synechocystis sp.

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    Heng, Ri-Liang; Pilon, Laurent

    2016-05-01

    This study presents experimental measurements of the radiation characteristics of unicellular freshwater cyanobacterium Synechocystis sp. during their exponential growth in F medium. Their scattering phase function at 633 nm average spectral absorption and scattering cross-sections between 400 and 750 nm were measured. In addition, an inverse method was used for retrieving the spectral effective complex index of refraction of overlapping or touching bispheres and quadspheres from their absorption and scattering cross-sections. The inverse method combines a genetic algorithm and a forward model based on Lorenz-Mie theory, treating bispheres and quadspheres as projected area and volume-equivalent coated spheres. The inverse method was successfully validated with numerically predicted average absorption and scattering cross-sections of suspensions consisting of bispheres and quadspheres, with realistic size distributions, using the T-matrix method. It was able to retrieve the monomers' complex index of refraction with size parameter up to 11, relative refraction index less than 1.3, and absorption index less than 0.1. Then, the inverse method was applied to retrieve the effective spectral complex index of refraction of Synechocystis sp. approximated as randomly oriented aggregates consisting of two overlapping homogeneous spheres. Both the measured absorption cross-section and the retrieved absorption index featured peaks at 435 and 676 nm corresponding to chlorophyll a, a peak at 625 nm corresponding to phycocyanin, and a shoulder around 485 nm corresponding to carotenoids. These results can be used to optimize and control light transfer in photobioreactors. The inverse method and the equivalent coated sphere model could be applied to other optically soft particles of similar morphologies.

  3. Using oxidized liquid and solid human waste as nutrients for Chlorella vulgaris and cyanobacterium Oscillatoria deflexa

    Science.gov (United States)

    Trifonov, Sergey V.; Kalacheva, Galina; Tirranen, Lyalya; Gribovskaya, Iliada

    At stationary terrestrial and space stations with closed and partially closed substance exchange not only plants, but also algae can regenerate atmosphere. Their biomass can be used for feeding Daphnia and Moina species, which, in their turn, serve as food for fish. In addition, it is possible to use algae for production of biological fuel. We suggested two methods of human waste mineralization: dry (evaporation with subsequent incineration in a muffle furnace) and wet (oxidation in a reactor using hydrogen peroxide). The research task was to prepare nutrient media for green alga Chlorella vulgaris and cyanobacterium Oscillatoria deflexa using liquid human waste mineralized by dry method, and to prepare media for chlorella on the basis of 1) liquid and 2) liquid and solid human waste mineralized by wet method. The algae were grown in batch culture in a climate chamber with the following parameters: illumination 7 klx, temperature 27-30 (°) C, culture density 1-2 g/l of dry weight. The control for chlorella was Tamiya medium, pH-5, and for oscillstoria — Zarrouk medium, pH-10. Maximum permissible concentrations of NaCl, Cl, urea (NH _{2}) _{2}CO, and native urine were established for algae. Missing ingredients (such as salts and acids) for experimental nutrient media were determined: their addition made it possible to obtain the biomass production not less than that in the control. The estimation was given of the mineral and biochemical composition of algae grown on experimental media. Microbiological test revealed absence of foreign microbial flora in experimental cultures.

  4. Isolation and characterization of a cyanophage infecting the toxic cyanobacterium Microcystis aeruginosa.

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    Yoshida, Takashi; Takashima, Yukari; Tomaru, Yuji; Shirai, Yoko; Takao, Yoshitake; Hiroishi, Shingo; Nagasaki, Keizo

    2006-02-01

    We isolated a cyanophage (Ma-LMM01) that specifically infects a toxic strain of the bloom-forming cyanobacterium Microcystis aeruginosa. Transmission electron microscopy showed that the virion is composed of anisometric head and a tail complex consisting of a central tube and a contractile sheath with helical symmetry. The morphological features and the host specificity suggest that Ma-LMM01 is a member of the cyanomyovirus group. Using semi-one-step growth experiments, the latent period and burst size were estimated to be 6 to 12 h and 50 to 120 infectious units per cell, respectively. The size of the phage genome was estimated to be ca. 160 kbp using pulse-field gel electrophoresis; the nucleic acid was sensitive to DNase I, Bal31, and all 14 restriction enzymes tested, suggesting that it is a linear double-stranded DNA having a low level of methylation. Phylogenetic analyses based on the deduced amino acid sequences of two open reading frames coding for ribonucleotide reductase alpha- and beta-subunits showed that Ma-LMM01 forms a sister group with marine and freshwater cyanobacteria and is apparently distinct from T4-like phages. Phylogenetic analysis of the deduced amino acid sequence of the putative sheath protein showed that Ma-LMM01 does not form a monophyletic group with either the T4-like phages or prophages, suggesting that Ma-LMM01 is distinct from other T4-like phages that have been described despite morphological similarity. The host-phage system which we studied is expected to contribute to our understanding of the ecology of Microcystis blooms and the genetics of cyanophages, and our results suggest the phages could be used to control toxic cyanobacterial blooms.

  5. Isolation and in silico analysis of Fe-superoxide dismutase in the cyanobacterium Nostoc commune.

    Science.gov (United States)

    Kesheri, Minu; Kanchan, Swarna; Richa; Sinha, Rajeshwar P

    2014-12-15

    Cyanobacteria are known to endure various stress conditions due to the inbuilt potential for oxidative stress alleviation owing to the presence of an array of antioxidants. The present study shows that Antarctic cyanobacterium Nostoc commune possesses two antioxidative enzymes viz., superoxide dismutase (SOD) and catalase that jointly cope with environmental stresses prevailing at its natural habitat. Native-PAGE analysis illustrates the presence of a single prominent isoform recognized as Fe-SOD and three distinct isoforms of catalase. The protein sequence of Fe-SOD in N. commune retrieved from NCBI protein sequence database was used for in silico analysis. 3D structure of N. commune was predicted by comparative modeling using MODELLER 9v11. Further, this model was validated for its quality by Ramachandran plot, ERRAT, Verify 3D and ProSA-web which revealed good structure quality of the model. Multiple sequence alignment showed high conservation in N and C-terminal domain regions along with all metal binding positions in Fe-SOD which were also found to be highly conserved in all 28 cyanobacterial species under study, including N. commune. In silico prediction of isoelectric point and molecular weight of Fe-SOD was found to be 5.48 and 22,342.98Da respectively. The phylogenetic tree revealed that among 28 cyanobacterial species, Fe-SOD in N. commune was the closest evolutionary homolog of Fe-SOD in Nostoc punctiforme as evident by strong bootstrap value. Thus, N. commune may serve as a good biological model for studies related to survival of life under extreme conditions prevailing at the Antarctic region. Moreover cyanobacteria may be exploited for biochemical and biotechnological applications of enzymatic antioxidants. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Isolation and characterization of the small subunit of the uptake hydrogenase from the cyanobacterium Nostoc punctiforme.

    Science.gov (United States)

    Raleiras, Patrícia; Kellers, Petra; Lindblad, Peter; Styring, Stenbjörn; Magnuson, Ann

    2013-06-21

    In nitrogen-fixing cyanobacteria, hydrogen evolution is associated with hydrogenases and nitrogenase, making these enzymes interesting targets for genetic engineering aimed at increased hydrogen production. Nostoc punctiforme ATCC 29133 is a filamentous cyanobacterium that expresses the uptake hydrogenase HupSL in heterocysts under nitrogen-fixing conditions. Little is known about the structural and biophysical properties of HupSL. The small subunit, HupS, has been postulated to contain three iron-sulfur clusters, but the details regarding their nature have been unclear due to unusual cluster binding motifs in the amino acid sequence. We now report the cloning and heterologous expression of Nostoc punctiforme HupS as a fusion protein, f-HupS. We have characterized the anaerobically purified protein by UV-visible and EPR spectroscopies. Our results show that f-HupS contains three iron-sulfur clusters. UV-visible absorption of f-HupS has bands ∼340 and 420 nm, typical for iron-sulfur clusters. The EPR spectrum of the oxidized f-HupS shows a narrow g = 2.023 resonance, characteristic of a low-spin (S = ½) [3Fe-4S] cluster. The reduced f-HupS presents complex EPR spectra with overlapping resonances centered on g = 1.94, g = 1.91, and g = 1.88, typical of low-spin (S = ½) [4Fe-4S] clusters. Analysis of the spectroscopic data allowed us to distinguish between two species attributable to two distinct [4Fe-4S] clusters, in addition to the [3Fe-4S] cluster. This indicates that f-HupS binds [4Fe-4S] clusters despite the presence of unusual coordinating amino acids. Furthermore, our expression and purification of what seems to be an intact HupS protein allows future studies on the significance of ligand nature on redox properties of the iron-sulfur clusters of HupS.

  7. Hopanoids play a role in stress tolerance and nutrient storage in the cyanobacterium Nostoc punctiforme.

    Science.gov (United States)

    Ricci, J N; Morton, R; Kulkarni, G; Summers, M L; Newman, D K

    2017-01-01

    Hopanes are abundant in ancient sedimentary rocks at discrete intervals in Earth history, yet interpreting their significance in the geologic record is complicated by our incomplete knowledge of what their progenitors, hopanoids, do in modern cells. To date, few studies have addressed the breadth of diversity of physiological functions of these lipids and whether those functions are conserved across the hopanoid-producing bacterial phyla. Here, we generated mutants in the filamentous cyanobacterium, Nostoc punctiforme, that are unable to make all hopanoids (shc) or 2-methylhopanoids (hpnP). While the absence of hopanoids impedes growth of vegetative cells at high temperature, the shc mutant grows faster at low temperature. This finding is consistent with hopanoids acting as membrane rigidifiers, a function shared by other hopanoid-producing phyla. Apart from impacting fitness under temperature stress, hopanoids are dispensable for vegetative cells under other stress conditions. However, hopanoids are required for stress tolerance in akinetes, a resting survival cell type. While 2-methylated hopanoids do not appear to contribute to any stress phenotype, total hopanoids and to a lesser extent 2-methylhopanoids were found to promote the formation of cyanophycin granules in akinetes. Finally, although hopanoids support symbiotic interactions between Alphaproteobacteria and plants, they do not appear to facilitate symbiosis between N. punctiforme and the hornwort Anthoceros punctatus. Collectively, these findings support interpreting hopanes as general environmental stress biomarkers. If hopanoid-mediated enhancement of nitrogen-rich storage products turns out to be a conserved phenomenon in other organisms, a better understanding of this relationship may help us parse the enrichment of 2-methylhopanes in the rock record during episodes of disrupted nutrient cycling. © 2016 John Wiley & Sons Ltd.

  8. Global transcriptional profiles of the copper responses in the cyanobacterium Synechocystis sp. PCC 6803.

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    Joaquin Giner-Lamia

    Full Text Available Copper is an essential element involved in fundamental processes like respiration and photosynthesis. However, it becomes toxic at high concentration, which has forced organisms to control its cellular concentration. We have recently described a copper resistance system in the cyanobacterium Synechocystis sp. PCC 6803, which is mediated by the two-component system, CopRS, a RND metal transport system, CopBAC and a protein of unknown function, CopM. Here, we report the transcriptional responses to copper additions at non-toxic (0.3 µM and toxic concentrations (3 µM in the wild type and in the copper sensitive copR mutant strain. While 0.3 µM copper slightly stimulated metabolism and promoted the exchange between cytochrome c6 and plastocyanin as soluble electron carriers, the addition of 3 µM copper catalyzed the formation of ROS, led to a general stress response and induced expression of Fe-S cluster biogenesis genes. According to this, a double mutant strain copRsufR, which expresses constitutively the sufBCDS operon, tolerated higher copper concentration than the copR mutant strain, suggesting that Fe-S clusters are direct targets of copper toxicity in Synechocystis. In addition we have also demonstrated that InrS, a nickel binding transcriptional repressor that belong to the CsoR family of transcriptional factor, was involved in heavy metal homeostasis, including copper, in Synechocystis. Finally, global gene expression analysis of the copR mutant strain suggested that CopRS only controls the expression of copMRS and copBAC operons in response to copper.

  9. Highly plastic genome of Microcystis aeruginosa PCC 7806, a ubiquitous toxic freshwater cyanobacterium

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    Latifi Amel

    2008-06-01

    Full Text Available Abstract Background The colonial cyanobacterium Microcystis proliferates in a wide range of freshwater ecosystems and is exposed to changing environmental factors during its life cycle. Microcystis blooms are often toxic, potentially fatal to animals and humans, and may cause environmental problems. There has been little investigation of the genomics of these cyanobacteria. Results Deciphering the 5,172,804 bp sequence of Microcystis aeruginosa PCC 7806 has revealed the high plasticity of its genome: 11.7% DNA repeats containing more than 1,000 bases, 6.8% putative transposases and 21 putative restriction enzymes. Compared to the genomes of other cyanobacterial lineages, strain PCC 7806 contains a large number of atypical genes that may have been acquired by lateral transfers. Metabolic pathways, such as fermentation and a methionine salvage pathway, have been identified, as have genes for programmed cell death that may be related to the rapid disappearance of Microcystis blooms in nature. Analysis of the PCC 7806 genome also reveals striking novel biosynthetic features that might help to elucidate the ecological impact of secondary metabolites and lead to the discovery of novel metabolites for new biotechnological applications. M. aeruginosa and other large cyanobacterial genomes exhibit a rapid loss of synteny in contrast to other microbial genomes. Conclusion Microcystis aeruginosa PCC 7806 appears to have adopted an evolutionary strategy relying on unusual genome plasticity to adapt to eutrophic freshwater ecosystems, a property shared by another strain of M. aeruginosa (NIES-843. Comparisons of the genomes of PCC 7806 and other cyanobacterial strains indicate that a similar strategy may have also been used by the marine strain Crocosphaera watsonii WH8501 to adapt to other ecological niches, such as oligotrophic open oceans.

  10. Efficient Gene Induction and Endogenous Gene Repression Systems for the Filamentous Cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Higo, Akiyoshi; Isu, Atsuko; Fukaya, Yuki; Hisabori, Toru

    2016-02-01

    In the last decade, many studies have been conducted to employ genetically engineered cyanobacteria in the production of various metabolites. However, the lack of a strict gene regulation system in cyanobacteria has hampered these attempts. The filamentous cyanobacterium Anabaena sp. PCC 7120 performs both nitrogen and carbon fixation and is, therefore, a good candidate organism for such production. To employ Anabaena cells for this purpose, we intended to develop artificial gene regulation systems to alter the cell metabolic pathways efficiently. We introduced into Anabaena a transcriptional repressor TetR, widely used in diverse organisms, and green fluorescent protein (GFP) as a reporter. We found that anhydrotetracycline (aTc) substantially induced GFP fluorescence in a concentration-dependent manner. By expressing tetR under the nitrate-specific promoter nirA, we successfully reduced the concentration of aTc required for the induction of gfp under nitrogen fixation conditions (to 10% of the concentration needed under nitrate-replete conditions). Further, we succeeded in the overexpression of GFP by depletion of nitrate without the inducer by means of promoter engineering of the nirA promoter. Moreover, we applied these gene regulation systems to a metabolic enzyme in Anabaena and successfully repressed glnA, the gene encoding glutamine synthetase that is essential for nitrogen assimilation in cyanobacteria, by expressing the small antisense RNA for glnA. Consequently, the ammonium production of an ammonium-excreting Anabaena mutant was significantly enhanced. We therefore conclude that the gene regulation systems developed in this study are useful tools for the regulation of metabolic enzymes and will help to increase the production of desired substances in Anabaena.

  11. Oxidative stress and photoinhibition can be separated in the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Hakkila, Kaisa; Antal, Taras; Rehman, Ateeq Ur; Kurkela, Juha; Wada, Hajime; Vass, Imre; Tyystjärvi, Esa; Tyystjärvi, Taina

    2014-02-01

    Roles of oxidative stress and photoinhibition in high light acclimation were studied using a regulatory mutant of the cyanobacterium Synechocystis sp. PCC 6803. The mutant strain ΔsigCDE contains the stress responsive SigB as the only functional group 2 σ factor. The ∆sigCDE strain grew more slowly than the control strain in methyl-viologen-induced oxidative stress. Furthermore, a fluorescence dye detecting H2O2, hydroxyl and peroxyl radicals and peroxynitrite, produced a stronger signal in ∆sigCDE than in the control strain, and immunological detection of carbonylated residues showed more protein oxidation in ∆sigCDE than in the control strain. These results indicate that ∆sigCDE suffers from oxidative stress in standard conditions. The oxidative stress may be explained by the findings that ∆sigCDE had a low content of glutathione and low amount of Flv3 protein functioning in the Mehler-like reaction. Although ∆sigCDE suffers from oxidative stress, up-regulation of photoprotective carotenoids and Flv4, Sll2018, Flv2 proteins protected PSII against light induced damage by quenching singlet oxygen more efficiently in ∆sigCDE than in the control strain in visible and in UV-A/B light. However, in UV-C light singlet oxygen is not produced and PSII damage occurred similarly in the ∆sigCDE and control strains. According to our results, resistance against the light-induced damage of PSII alone does not lead to high light tolerance of the cells, but in addition efficient protection against oxidative stress would be required. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Purification and properties of NADP-isocitrate dehydrogenase from the unicellular cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Muro-Pastor, M I; Florencio, F J

    1992-01-15

    NADP-dependent isocitrate dehydrogenase activity has been screened in several cyanobacteria grown on different nitrogen sources; in all the strains tested isocitrate dehydrogenase activity levels were similar in cells grown either on ammonium or nitrate. The enzyme from the unicellular cyanobacterium Synechocystis sp. PCC 6803 has been purified to electrophoretic homogeneity by a procedure that includes Reactive-Red-120-agarose affinity chromatography and phenyl-Sepharose chromatography as main steps. The enzyme was purified about 600-fold, with a yield of 38% and a specific activity of 15.7 U/mg protein. The native enzyme (108 kDa) is composed of two identical subunits with an apparent molecular mass of 57 kDa. Synechocystis isocitrate dehydrogenase was absolutely specific for NADP as electron acceptor. Apparent Km values were 125, 59 and 12 microM for Mg2+, D,L-isocitrate and NADP, respectively, using Mg2+ as divalent cation and 4, 5.7 and 6 microM for Mn2+, D,L-isocitrate and NADP, respectively, using Mn2+ as a cofactor. The enzyme was inhibited non-competitively by ADP (Ki, 6.4 mM) and 2-oxoglutarate, (Ki, 6 mM) with respect to isocitrate and in a competitive manner by NADPH (Ki, 0.6 mM). The circular-dichroism spectrum showed a protein with a secondary structure consisting of about 30% alpha-helix and 36% beta-pleated sheet. The enzyme is an acidic protein with an isoelectric point of 4.4 and analysis of the NH2-terminal sequence revealed 45% identity with the same region of Escherichia coli isocitrate dehydrogenase. The aforementioned data indicate that NADP isocitrate dehydrogenase from Synechocystis resembles isocitrate dehydrogenase from prokaryotes and shows similar molecular and structural properties to the well-known E. coli enzyme.

  13. Posttranslational regulation of nitrate assimilation in the cyanobacterium Synechocystis sp. strain PCC 6803.

    Science.gov (United States)

    Kobayashi, Masaki; Takatani, Nobuyuki; Tanigawa, Mari; Omata, Tatsuo

    2005-01-01

    Posttranslational regulation of nitrate assimilation was studied in the cyanobacterium Synechocystis sp. strain PCC 6803. The ABC-type nitrate and nitrite bispecific transporter encoded by the nrtABCD genes was completely inhibited by ammonium as in Synechococcus elongatus strain PCC 7942. Nitrate reductase was insensitive to ammonium, while it is inhibited in the Synechococcus strain. Nitrite reductase was also insensitive to ammonium. The inhibition of nitrate and nitrite transport required the PII protein (glnB gene product) and the C-terminal domain of NrtC, one of the two ATP-binding subunits of the transporter, as in the Synechococcus strain. Mutants expressing the PII derivatives in which Ala or Glu is substituted for the conserved Ser49, which has been shown to be the phosphorylation site in the Synechococcus strain, showed ammonium-promoted inhibition of nitrate uptake like that of the wild-type strain. The S49A and S49E substitutions in GlnB did not affect the regulation of the nitrate and nitrite transporter in Synechococcus either. These results indicated that the presence or absence of negative electric charge at the 49th position does not affect the activity of the PII protein to regulate the cyanobacterial ABC-type nitrate and nitrite transporter according to the cellular nitrogen status. This finding suggested that the permanent inhibition of nitrate assimilation by an S49A derivative of PII, as was previously reported for Synechococcus elongatus strain PCC 7942, is likely to have resulted from inhibition of nitrate reductase rather than the nitrate and nitrite transporter.

  14. A pilot-scale floating closed culture system for the multicellular cyanobacterium Arthrospira platensis NIES-39.

    Science.gov (United States)

    Toyoshima, Masakazu; Aikawa, Shimpei; Yamagishi, Takahiro; Kondo, Akihiko; Kawai, Hiroshi

    Microalgae are considered to be efficient bio-resources for biofuels and bio-based chemicals because they generally have high productivity. The filamentous cyanobacterium Arthrospira (Spirulina) platensis has been widely used for food, feed, and nutrient supplements and is usually cultivated in open ponds. In order to extend the surface area for growing this alga, we designed a pilot-scale floating closed culture system for cultivating A. platensis on open water and compared the growth and quality of the alga harvested at both subtropical and temperate regions. The biomass productivity of A. platensis NIES-39 was ca. 9 g dry biomass m(-2) day(-1) in summer at Awaji Island (warm temperature region) and ca. 10 and 6 g dry biomass m(-2) day(-1) in autumn and winter, respectively, at Ishigaki Island, (subtropical region) in Japan. If seawater can be used for culture media, culture cost can be reduced; therefore, we examined the influence of seawater salt concentrations on the growth of A. platensis NIES-39. Growth rates of A. platensis NIES-39 in diluted seawater with enrichment of 2.5 g L(-1) NaNO3, 0.01 g L(-1) FeSO4·7H2O, and 0.08 g L(-1) Na2EDTA were considerably lower than SOT medium, but the biomass productivity (dry weight) was comparable to SOT medium. This is explained by the heavier cell weight of the alga grown in modified seawater media compared to the alga grown in SOT medium. Furthermore, A. platensis grown in modified seawater-based medium exhibited self-flocculation and had more loosely coiled trichomes.

  15. A review of the global ecology, genomics, and biogeography of the toxic cyanobacterium, Microcystis spp.

    Science.gov (United States)

    Harke, Matthew J; Steffen, Morgan M; Gobler, Christopher J; Otten, Timothy G; Wilhelm, Steven W; Wood, Susanna A; Paerl, Hans W

    2016-04-01

    This review summarizes the present state of knowledge regarding the toxic, bloom-forming cyanobacterium, Microcystis, with a specific focus on its geographic distribution, toxins, genomics, phylogeny, and ecology. A global analysis found documentation suggesting geographic expansion of Microcystis, with recorded blooms in at least 108 countries, 79 of which have also reported the hepatatoxin microcystin. The production of microcystins (originally "Fast-Death Factor") by Microcystis and factors that control synthesis of this toxin are reviewed, as well as the putative ecophysiological roles of this metabolite. Molecular biological analyses have provided significant insight into the ecology and physiology of Microcystis, as well as revealed the highly dynamic, and potentially unstable, nature of its genome. A genetic sequence analysis of 27 Microcystis species, including 15 complete/draft genomes are presented. Using the strictest biological definition of what constitutes a bacterial species, these analyses indicate that all Microcystis species warrant placement into the same species complex since the average nucleotide identity values were above 95%, 16S rRNA nucleotide identity scores exceeded 99%, and DNA-DNA hybridization was consistently greater than 70%. The review further provides evidence from around the globe for the key role that both nitrogen and phosphorus play in controlling Microcystis bloom dynamics, and the effect of elevated temperature on bloom intensification. Finally, highlighted is the ability of Microcystis assemblages to minimize their mortality losses by resisting grazing by zooplankton and bivalves, as well as viral lysis, and discuss factors facilitating assemblage resilience. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. IMPORTANT NOTIFICATION

    CERN Multimedia

    HR Department

    2009-01-01

    Green plates, removals and importation of personal effects Please note that, as from 1 April 2009, formalities relating to K and CD special series French vehicle plates (green plates), removals and importation of personal effects into France and Switzerland will be dealt with by GS Department (Building 73/3-014, tel. 73683/74407). Importation and purchase of tax-free vehicles in Switzerland, as well as diplomatic privileges, will continue to be dealt with by the Installation Service of HR Department (Building 33/1-011, tel. 73962). HR and GS Departments

  17. Localization of Membrane Proteins in the Cyanobacterium Synechococcus sp. PCC7942 (Radial Asymmetry in the Photosynthetic Complexes).

    Science.gov (United States)

    Sherman, D. M.; Troyan, T. A.; Sherman, L. A.

    1994-09-01

    Localization of membrane proteins in the cyanobacterium Synechococcus sp. PCC7942 was determined by transmission electron microscopy utilizing immunocytochemistry with cells prepared by freeze-substitution. This preparation procedure maintained cellular morphology and permitted detection of cellular antigens with high sensitivity and low background. Synechococcus sp. PCC7942 is a unicellular cyanobacterium with thylakoids organized in concentric layers toward the periphery of the cell. Cytochrome oxidase was localized almost entirely in the cytoplasmic membrane, whereas a carotenoprotein (P35) was shown to be a cell wall component. The major photosystem II (PSII) proteins (D1, D2 CP43, and CP47) were localized throughout the thylakoids. Proteins of the Cyt b6/f complex were found to have a similar distribution. Thylakoid luminal proteins, such as the Mn-stabilizing protein, were located primarily in the thylakoid, but a small, reproducible fraction was found in the outer compartment. The photosystem I (PSI) reaction center proteins and the ATP synthase proteins were found associated mostly with the outermost thylakoid and with the cytoplasmic membrane. These results indicated that the photosynthetic apparatus is not evenly distributed throughout the thylakoids. Rather, there is a radial asymmetry such that much of the PSI and the ATPase synthase is located in the outermost thylakoid. The relationship of this structure to the photosynthetic mechanism is discussed. It is suggested that the photosystems are separated because of kinetic differences between PSII and PSI, as hypothesized by H.-W. Trissl and C. Wilhelm (Trends Biochem Sci [1993] 18:415-419).

  18. Cultivation and characterization of the MaMV-DC cyanophage that infects bloom-forming cyanobacterium Microcystis aeruginosa.

    Science.gov (United States)

    Ou, Tong; Li, Sanhua; Liao, Xiangyong; Zhang, Qiya

    2013-10-01

    The MaMV-DC cyanophage, which infects the bloom-forming cyanobacterium Microcystis aeruginosa, was isolated from Lake Dianchi, Kunming, China. Twenty-one cyanobacterial strains were used to detect the host range of MaMV-DC. Microcystic aeruginosa FACHB-524 and plaque purification were used to isolate individual cyanophages, and culturing MaMV-DC with cyanobacteria allowed us to prepare purified cyanophages for further analysis. Electron microscopy demonstrated that the negatively stained viral particles are tadpole-shaped with an icosahedral head approximately 70 nm in diameter and a contractile tail approximately 160 nm in length. Using one-step growth experiments, the latent period and burst size of MaMV-DC were estimated to be 24-48 hours and approximately 80 infectious units per cell, respectively. Restriction endonuclease digestion and agarose gel electrophoresis were performed using purified MaMV-DC genomic DNA, and the genome size was estimated to be approximately 160 kb. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis revealed four major structural proteins. These results support the growing interest in using freshwater cyanophages to control bloom-forming cyanobacterium.

  19. Characterization of the coccoid cyanobacterium Myxosarcina sp. KIOST-1 isolated from mangrove forest in Chuuk State, Federated States of Micronesia

    Science.gov (United States)

    Kim, Ji Hyung; Lee, JunMo; Affan, Md-Abu; Lee, Dae-Won; Kang, Do-Hyung

    2017-05-01

    Mangrove forests are known to be inhabited by diverse symbiotic cyanobacterial communities that are capable of N2 fixation. To investigate its biodiversity, root sediments were collected from a mangrove forest in Chuuk State, Federated States of Micronesia (FSM), and an entangled yellow-brown coccoid cyanobacterium was isolated. The isolated cyanobacterium was reproduced by multiple fission and eventually produced baeocytes. Phylogenetic analysis revealed that the isolate was most similar to the genera Myxosarcina and Chroococcidiopsis in the order Pleurocapsales. Compositions of protein, lipid and carbohydrate in the cyanobacterial cells were estimated to be 19.4 ± 0.1%, 18.8 ± 0.4% and 31.5 ± 0.1%, respectively. Interestingly, total fatty acids in the isolate were mainly composed of saturated fatty acids and monounsaturated fatty acids, whereas polyunsaturated fatty acids were not detected. Based on the molecular and biochemical characteristics, the isolate was finally classified in the genus Myxosarcina, and designated as Myxosarcina sp. KIOST-1. These results will contribute to better understanding of cyanobacterial biodiversity in the mangrove forest in FSM as well as the genus Myxosarcina, and also will allow further exploitation of its biotechnological potential on the basis of its cellular characteristics.

  20. High Iron Requirement for Growth, Photosynthesis, and Low-light Acclimation in the Marine Cyanobacterium Synechococcus bacillaris

    Science.gov (United States)

    Sunda, W. G.; Huntsman, S. A.

    2016-02-01

    Iron is a critical nutrient in photosynthesis and limits phytoplankton growth in large regions of the ocean. Most of the iron in phytoplankton occurs in iron-containing proteins in the photosynthetic apparatus, and thus interactions among cellular iron, light, and growth rate are predicted. In agreement with this prediction, decreasing light intensity increased the cellular iron:carbon (Fe:C) ratio needed to support a given growth rate by 2- to 3-fold in both a coastal diatom Thalassiosira pseudonana, and a coastal cyanobacterium Synechococcus bacillaris due to an increase in iron-containing photosynthetic units. However, although the light responses were similar, the cellular Fe:C ratios needed to support a given growth rate were 5- to 8-fold higher in the cyanobacterium than in the diatom, a pattern seen in other Syechococcus isolates and eukaryotic phytoplankton. Due to the high iron requirement for growth and low light acclimation, we might expect Synechococcus to be at a competitive disadvantage in many low-iron and low-light environments. Indeed, it decreases rapidly with depth within the ocean's deep chlorophyll maximum (DCM), where iron and light levels are low and lower-iron requiring eukaryotic algae typically dominate the phytoplankton biomass in the mid to lower DCM.

  1. A Nostoc punctiforme Sugar Transporter Necessary to Establish a Cyanobacterium-Plant Symbiosis1[C][W

    Science.gov (United States)

    Ekman, Martin; Picossi, Silvia; Campbell, Elsie L.; Meeks, John C.; Flores, Enrique

    2013-01-01

    In cyanobacteria-plant symbioses, the symbiotic nitrogen-fixing cyanobacterium has low photosynthetic activity and is supplemented by sugars provided by the plant partner. Which sugars and cyanobacterial sugar uptake mechanism(s) are involved in the symbiosis, however, is unknown. Mutants of the symbiotically competent, facultatively heterotrophic cyanobacterium Nostoc punctiforme were constructed bearing a neomycin resistance gene cassette replacing genes in a putative sugar transport gene cluster. Results of transport activity assays using 14C-labeled fructose and glucose and tests of heterotrophic growth with these sugars enabled the identification of an ATP-binding cassette-type transporter for fructose (Frt), a major facilitator permease for glucose (GlcP), and a porin needed for the optimal uptake of both fructose and glucose. Analysis of green fluorescent protein fluorescence in strains of N. punctiforme bearing frt::gfp fusions showed high expression in vegetative cells and akinetes, variable expression in hormogonia, and no expression in heterocysts. The symbiotic efficiency of N. punctiforme sugar transport mutants was investigated by testing their ability to infect a nonvascular plant partner, the hornwort Anthoceros punctatus. Strains that were specifically unable to transport glucose did not infect the plant. These results imply a role for GlcP in establishing symbiosis under the conditions used in this work. PMID:23463784

  2. Arabinogalactan proteins occur in the free-living cyanobacterium genus Nostoc and in plant-Nostoc symbioses.

    Science.gov (United States)

    Jackson, Owen; Taylor, Oliver; Adams, David G; Knox, J Paul

    2012-10-01

    Arabinogalactan proteins (AGP) are a diverse family of proteoglycans associated with the cell surfaces of plants. AGP have been implicated in a wide variety of plant cell processes, including signaling in symbioses. This study investigates the existence of putative AGP in free-living cyanobacterial cultures of the nitrogen-fixing, filamentous cyanobacteria Nostoc punctiforme and Nostoc sp. strain LBG1 and at the symbiotic interface in the symbioses between Nostoc spp. and two host plants, the angiosperm Gunnera manicata (in which the cyanobacterium is intracellular) and the liverwort Blasia pusilla (in which the cyanobacterium is extracellular). Enzyme-linked immunosorbent assay, immunoblotting, and immunofluorescence analyses demonstrated that three AGP glycan epitopes (recognized by monoclonal antibodies LM14, MAC207, and LM2) are present in free-living Nostoc cyanobacterial species. The same three AGP glycan epitopes are present at the Gunnera-Nostoc symbiotic interface and the LM2 epitope is detected during the establishment of the Blasia-Nostoc symbiosis. Bioinformatic analysis of the N. punctiforme genome identified five putative AGP core proteins that are representative of AGP classes found in plants. These results suggest a possible involvement of AGP in cyanobacterial-plant symbioses and are also suggestive of a cyanobacterial origin of AGP.

  3. The effects of the exopolysaccharide and growth rate on the morphogenesis of the terrestrial filamentous cyanobacterium Nostoc flagelliforme

    Directory of Open Access Journals (Sweden)

    Lijuan Cui

    2017-09-01

    Full Text Available The terrestrial cyanobacterium Nostoc flagelliforme, which contributes to carbon and nitrogen supplies in arid and semi-arid regions, adopts a filamentous colony form. Owing to its herbal and dietary values, this species has been overexploited. Largely due to the lack of understanding on its morphogenesis, artificial cultivation has not been achieved. Additionally, it may serve as a useful model for recognizing the morphological adaptation of colonial cyanobacteria in terrestrial niches. However, it shows very slow growth in native habitats and is easily disintegrated under laboratory conditions. Thus, a novel experimental system is necessary to explore its morphogenetic mechanism. Liquid-cultured N. flagelliforme has been well developed for exopolysaccharide (EPS production, in which microscopic colonies (micro-colonies are generally formed. In this study, we sought to gain some insight into the morphogenesis of N. flagelliforme by examining the effects of two external factors, the EPS and environmental stress-related growth rate, on the morphological shaping of micro-colonies. Our findings indicate that the EPS matrix could act as a basal barrier, leading to the bending of trichomes during their elongation, while very slow growth is conducive to their straight elongation. These findings will guide future cultivation and application of this cyanobacterium for ecological improvement.

  4. Pathway-level acceleration of glycogen catabolism by a response regulator in the cyanobacterium Synechocystis species PCC 6803.

    Science.gov (United States)

    Osanai, Takashi; Oikawa, Akira; Numata, Keiji; Kuwahara, Ayuko; Iijima, Hiroko; Doi, Yoshiharu; Saito, Kazuki; Hirai, Masami Yokota

    2014-04-01

    Response regulators of two-component systems play pivotal roles in the transcriptional regulation of responses to environmental signals in bacteria. Rre37, an OmpR-type response regulator, is induced by nitrogen depletion in the unicellular cyanobacterium Synechocystis species PCC 6803. Microarray and quantitative real-time polymerase chain reaction analyses revealed that genes related to sugar catabolism and nitrogen metabolism were up-regulated by rre37 overexpression. Protein levels of GlgP(slr1367), one of the two glycogen phosphorylases, in the rre37-overexpressing strain were higher than those of the parental wild-type strain under both nitrogen-replete and nitrogen-depleted conditions. Glycogen amounts decreased to less than one-tenth by rre37 overexpression under nitrogen-replete conditions. Metabolome analysis revealed that metabolites of the sugar catabolic pathway and amino acids were altered in the rre37-overexpressing strain after nitrogen depletion. These results demonstrate that Rre37 is a pathway-level regulator that activates the metabolic flow from glycogen to polyhydroxybutyrate and the hybrid tricarboxylic acid and ornithine cycle, unraveling the mechanism of the transcriptional regulation of primary metabolism in this unicellular cyanobacterium.

  5. Artificially acquired chlorophyll b is highly acceptable to the thylakoid-lacking cyanobacterium, Gloeobacter violaceus PCC 7421.

    Science.gov (United States)

    Araki, Mie; Akimoto, Seiji; Mimuro, Mamoru; Tsuchiya, Tohru

    2014-08-01

    Unicellular cyanobacterium Gloeobacter violaceus is an only known oxygenic photosynthetic organism that lacks thylakoid membrane. Molecular phylogenetic analyses indicate that G. violaceus is an early-branching cyanobacterium within cyanobacterial clade. Therefore, the photosynthetic system of G. violaceus is considered to be partly similar to that of the ancestral cyanobacteria that would lack thylakoid membrane. G. violaceus possesses chlorophyll (Chl) a as the only chlorophyll species like most cyanobacteria. It was proposed that the ancestral oxygenic photosynthetic organism had not only Chl a and phycobilins but also Chl b. However, no organism which contains both Chl a and Chl b and lacks thylakoid membrane has been found in nature. Therefore, we introduced the chlorophyllide a oxygenase gene responsible for Chl b biosynthesis into G. violaceus. In the resultant transformant, Chl b accumulated at approximately 11% of total Chl independent of growth phase. Photosystem I complexes isolated from the transformant contained Chl b at 9.9% of total Chl. The presence of Chl b in the photosystem I complexes did not inhibit trimer formation. Furthermore, time-resolved fluorescence spectrum demonstrated that Chl b transferred energy to Chl a in the photosystem I complexes and did not disturb the energy transfer among the Chl a molecules. These results show that G. violaceus is tolerant to artificially produced Chl b and suggest the flexibility of photosystem for Chl composition in the ancestral oxygenic photosynthetic organism.

  6. Novel Insights into the Regulation of LexA in the Cyanobacterium Synechocystis sp. Strain PCC 6803 ▿ †

    Science.gov (United States)

    Oliveira, Paulo; Lindblad, Peter

    2011-01-01

    The transcription factor LexA in the cyanobacterium Synechocystis sp. strain PCC 6803 has been shown to regulate genes that are not directly involved in DNA repair but instead in several different metabolic pathways. However, the signal transduction pathways remain largely uncharacterized. The present work gives novel insights into the regulation of LexA in this unicellular cyanobacterium. A combination of Northern and Western blotting, using specific antibodies against the cyanobacterial LexA, was employed to show that this transcription regulator is under posttranscriptional control, in addition to the classical and already-described transcriptional regulation. Moreover, detailed two-dimensional (2D) electrophoresis analyses of the protein revealed that LexA undergoes posttranslational modifications. Finally, a fully segregated LexA::GFP (green fluorescent protein) fusion-modified strain was produced to image LexA's spatial distribution in live cells. The fusion protein retains DNA binding capabilities, and the GFP fluorescence indicates that LexA is localized in the innermost region of the cytoplasm, decorating the DNA in an evenly distributed pattern. The implications of these findings for the overall role of LexA in Synechocystis sp. strain PCC 6803 are further discussed. PMID:21642463

  7. Enhancement of human adaptive immune responses by administration of a high-molecular-weight polysaccharide extract from the cyanobacterium Arthrospira platensis

    DEFF Research Database (Denmark)

    Pedersen, Morten Løbner; Walsted, Anette; Larsen, Rune

    2008-01-01

    The effect of consumption of Immulina, a high-molecular-weight polysaccharide extract from the cyanobacterium Arthrospira platensis, on adaptive immune responses was investigated by evaluation of changes in leukocyte responsiveness to two foreign recall antigens, Candida albicans (CA) and tetanus...

  8. Draft Genome Sequence of the Cyanobacterium Aphanizomenon flos-aquae Strain 2012/KM1/D3, Isolated from the Curonian Lagoon (Baltic Sea)

    National Research Council Canada - National Science Library

    Šulčius, Sigitas; Alzbutas, Gediminas; Kvederavičiūtė, Kotryna; Koreivienė, Judita; Zakrys, Linas; Lubys, Arvydas; Paškauskas, Ričardas

    2015-01-01

    We report here the de novo genome assembly of a cyanobacterium, Aphanizomenon flos-aquae strain 2012/KM1/D3, a harmful bloom-forming species in temperate aquatic ecosystems. The genome is 5.7 Mb with a G+C content of 38.2...

  9. Draft Genome Sequence of the Cyanobacterium Aphanizomenon flos-aquae Strain 2012/KM1/D3, Isolated from the Curonian Lagoon (Baltic Sea)

    OpenAIRE

    ?ul?ius, Sigitas; Alzbutas, Gediminas; Kvederavi?i?t?, Kotryna; Koreivien?, Judita; Zakrys, Linas; Lubys, Arvydas; Pa?kauskas, Ri?ardas

    2015-01-01

    We report here the de?novo genome assembly of a cyanobacterium, Aphanizomenon?flos-aquae strain 2012/KM1/D3, a harmful bloom-forming species in temperate aquatic ecosystems. The genome is 5.7?Mb with a G+C content of 38.2%, and it is enriched mostly with genes involved in amino acid and carbohydrate metabolism.

  10. Growth of Daphnia magna males and females fed with the cyanobacterium Microcystis aeruginosa and the green alga Scenedesmus obliquus in different proportions

    NARCIS (Netherlands)

    Lürling, M.F.L.L.W.; Beekman, W.

    2006-01-01

    Laboratory experiments were used to study the sensitivity of both male and female Daphnia magna to a toxic cyanobacterium, Microcystis aeruginosa. Male and female D. magna were fed with M. aeruginosa and a green alga (Scenedesmus obliquus) in different mixtures that included 0%, 25%, 50%, 75% and 10

  11. HupW Protease Specifically Required for Processing of the Catalytic Subunit of the Uptake Hydrogenase in the Cyanobacterium Nostoc sp. Strain PCC 7120

    Science.gov (United States)

    Lindberg, Pia; Devine, Ellenor; Stensjö, Karin

    2012-01-01

    The maturation process of [NiFe] hydrogenases includes a proteolytic cleavage of the large subunit. We constructed a mutant of Nostoc strain PCC 7120 in which hupW, encoding a putative hydrogenase-specific protease, is inactivated. Our results indicate that the protein product of hupW selectively cleaves the uptake hydrogenase in this cyanobacterium. PMID:22020512

  12. Quest for minor but key chlorophyll molecules in photosynthetic reaction centers - unusual pigment composition in the reaction centers of the chlorophyll d-dominated cyanobacterium Acaryochloris marina.

    Science.gov (United States)

    Akiyama, Machiko; Miyashita, Hideaki; Kise, Hideo; Watanabe, Tadashi; Mimuro, Mamoru; Miyachi, Shigetoh; Kobayashi, Masami

    2002-01-01

    A short overview, based on our own findings, is given of the minor pigments that function as key components in photosynthesis. Recently, we found the presence of chlorophyll a, chlorophyll d' and pheophytin a as minor pigments in the chlorophyll d-dominated cyanobacterium Acaryochloris marina.

  13. Effects of Microcystin-free and Microcystin-containing strains of the Cyanobacterium Microcystis aeruginosa on growth of the grazer Daphnia magna

    NARCIS (Netherlands)

    Lürling, M.F.L.L.W.

    2003-01-01

    Harmful effects of the common bloom-forming cyanobacterium Microcystis aeruginosa on the grazer Daphnia have been explained from morphological features, nutritional insufficiency, and the production of toxins called microcystins. The effects of four M. aeruginosa strains, including one free of

  14. Effects of microcystin-free and Microcystin containing strains of the cyanobacterium Microcystis aeruginosa on growth of the grazer Daphnia magna

    NARCIS (Netherlands)

    Lürling, M.

    2003-01-01

    Harmful effects of the common bloom-forming cyanobacterium Microcystis aeruginosa on the grazer Daphnia have been explained from morphological features, nutritional insufficiency, and the production of toxins called microcystins. The effects of four M. aeruginosa strains, including one free of

  15. Life-history characteristics of Daphnia exposed to dissolved microcystin-LR and to the cyanobacterium microcystis aeruginosa with and without microcystins

    NARCIS (Netherlands)

    Lürling, M.F.L.L.W.; Grinten, van der E.

    2003-01-01

    In the current study, the role of microcystin(MC)-LR in inhibiting Daphnia growth was examined. Somatic growth, time to first reproduction, number of newborns, mortality, and population growth were measured in Daphnia fed mixtures of the cyanobacterium Microcystis aeruginosa (with and without microc

  16. Interação entre fungos micorrízicos arbusculares e bactérias diazotróficas em trigo Interaction between arbuscular mycorrhizal fungi and diazotrophic bacteria in wheat plants

    Directory of Open Access Journals (Sweden)

    Valéria Marino Rodrigues Sala

    2007-11-01

    Full Text Available O objetivo deste trabalho foi avaliar o efeito da inoculação de dois novos isolados de bactérias diazotróficas endofíticas e da interação destas bactérias com fungos micorrízicos arbusculares (FMAs, na cultura do trigo. Foi realizado um experimento em casa de vegetação, com dois isolados de bactérias diazotróficas endofíticas, IAC11HT (Achromobacter insolitus e IAC12HT (Zoogloea ramigera, e dois FMAs (Glomus sp. e Acaulospora sp.. Houve efeito sinérgico da co-inoculação na colonização das raízes por bactérias diazotróficas, com o emprego do FMA do gênero Acaulospora. As plantas associadas a Glomus, na presença dos isolados bacterianos, apresentaram maior crescimento, acúmulo e aproveitamento dos nutrientes do que as plantas colonizadas por Acaulospora sp., entretanto, não superaram os tratamentos em que as bactérias e os fungos foram inoculados isoladamente. Apesar de não ter havido efeito benéfico da co-inoculação FMA-bactéria diazotrófica sobre a maioria dos parâmetros avaliados, essas novas bactérias propiciaram o dobro de crescimento, acúmulo e aproveitamento do N e P em plantas de trigo.The aim of this work was to evaluate the inoculation effect of two new endophytic diazotrophic bacteria and the interaction between arbuscular mycorrhizal fungi (AMF and these bacteria on wheat plants. The experiment was carried out in a greenhouse with the two strains of diazotrophic bacteria, IAC11HT (Achromobacter insolitus and IAC12HT (Zoogloea ramigera, and two AMF (Glomus sp. and Acaulospora sp.. There was synergistic effect of the co-inoculation on root colonization by diazotrophic bacteria with the AMF of the genus Acaulospora. The plants colonized by Glomus associated to bacterial strains showed higher growth, accumulation and exploitation of the nutrients than plants colonized by Acaulospora sp., however, this effect did not surpass the treatments in which bacteria and fungi were inoculated separately. Although

  17. Dynamics of N2 fixation and fate of diazotroph-derived nitrogen in a low-nutrient, low-chlorophyll ecosystem: results from the VAHINE mesocosm experiment (New Caledonia)

    Science.gov (United States)

    Bonnet, Sophie; Berthelot, Hugo; Turk-Kubo, Kendra; Fawcett, Sarah; Rahav, Eyal; L'Helguen, Stéphane; Berman-Frank, Ilana

    2016-05-01

    N2 fixation rates were measured daily in large (˜ 50 m3) mesocosms deployed in the tropical southwest Pacific coastal ocean (New Caledonia) to investigate the temporal variability in N2 fixation rates in relation with environmental parameters and study the fate of diazotroph-derived nitrogen (DDN) in a low-nutrient, low-chlorophyll ecosystem. The mesocosms were fertilized with ˜ 0.8 µM dissolved inorganic phosphorus (DIP) to stimulate diazotrophy. Bulk N2 fixation rates were replicable between the three mesocosms, averaged 18.5 ± 1.1 nmol N L-1 d-1 over the 23 days, and increased by a factor of 2 during the second half of the experiment (days 15 to 23) to reach 27.3 ± 1.0 nmol N L-1 d-1. These later rates measured after the DIP fertilization are higher than the upper range reported for the global ocean. During the 23 days of the experiment, N2 fixation rates were positively correlated with seawater temperature, primary production, bacterial production, standing stocks of particulate organic carbon (POC), nitrogen (PON) and phosphorus (POP), and alkaline phosphatase activity, and negatively correlated with DIP concentrations, DIP turnover time, nitrate, and dissolved organic nitrogen and phosphorus concentrations. The fate of DDN was investigated during a bloom of the unicellular diazotroph UCYN-C that occurred during the second half of the experiment. Quantification of diazotrophs in the sediment traps indicates that ˜ 10 % of UCYN-C from the water column was exported daily to the traps, representing as much as 22.4 ± 5.5 % of the total POC exported at the height of the UCYN-C bloom. This export was mainly due to the aggregation of small (5.7 ± 0.8 µm) UCYN-C cells into large (100-500 µm) aggregates. During the same time period, a DDN transfer experiment based on high-resolution nanometer-scale secondary ion mass spectrometry (nanoSIMS) coupled with 15N2 isotopic labeling revealed that 16 ± 6 % of the DDN was released to the dissolved pool and 21 ± 4

  18. Growth conditions of endophytic diazotroph isolated from Cynodon dactylon%狗牙根内生固氮菌生长条件

    Institute of Scientific and Technical Information of China (English)

    刘天增; 毛中伟; 张巨明

    2016-01-01

    从已分离的多个狗牙根(Cynodon dactylon)内生固氮菌株中筛选到两株固氮酶活性较高的菌株7 D和 BM13,为明确固氮菌株对环境因子的适应性,研究了在不同的生长环境条件下菌株的生长量.采用 Ashby无氮培养基,测定了温度、pH、渗透压以及不同氮源和碳源等环境条件对固氮菌生长的影响.结果表明,在10~40℃的温度范围内、pH 值3.92~9.64的酸碱环境和30 g.L-1 NaCl 的高渗透压下,固氮菌7D 和 BM13均能正常生长;菌株能耐受0~10 mmol.L-1的 NH4+和 NO3-,而且能利用蔗糖、甘油、麦芽糖、甘露醇和葡萄糖等多种碳源生长.说明狗牙根内生固氮菌株7 D和BM13对环境因子有很强的抗逆性和适应性,但两菌株之间存在一定差异,可望进一步研发成为优良的固氮微生物肥料生产菌种.%Effects of environmental factors on the growth of endophytic diazotroph strains 7D and BM13 isolated from Cynodon dactylon were investigated in our experiment.In this study,strains 7D and BM13 were exam-ined for their adaptability to the stress of temperature,pH,NaCl,NH4 +,NO3 - and carbon sources by Ashby media.The results showed that the two strains could grow under wide range of temperature of 10~40 ℃ and pH from 3.92~9.64.The strains could also tolerate NaCl concentrations of 30 g.L-1 ,NH4 + and NO3 - con-centrations of 0~10 mmol.L-1 ,respectively.The strains were capable of using various carbon sources.It was suggested that the strains 7D and BM13 had superior tolerance to stress of diverse environment factors,but their tolerance abilities differed partly.Endophytic diazotroph strain is a candidate to be further developed for microbial fertilizer production.

  19. Tolerância de bactérias diazotróficas simbióticas à salinidade in vitro Tolerance of diazotrophic symbiotic bacteria to salinity

    Directory of Open Access Journals (Sweden)

    Rafaela Simão Abrahão Nóbrega

    2004-08-01

    Full Text Available A busca de estirpes de bactérias diazotróficas simbióticas tolerantes à salinidade, em conjunto com a seleção de hospedeiros, tem por objetivo aumentar o desempenho da simbiose e manter a produtividade vegetal de forma sustentada em condições de estresse salino. Doze estirpes de bactérias diazotróficas de diferentes procedências foram estudadas quanto à tolerância a diferentes concentrações de NaCl em meios de cultura 79 e LB. As estirpes que apresentaram maior tolerância à salinidade (30 g L-1 em meio 79 foram: BR 6806 e BR 4007, ambas de crescimento rápido isoladas de solos do nordeste brasileiro, UFLA 03-51 e UFLA 03-65, de crescimento rápido e UFLA 03-84, de crescimento lento, sendo as três últimas oriundas da região Amazônica. Essas também estiveram entre as mais tolerantes em meio de cultura LB. A estirpe UFLA 03-84, selecionada em trabalhos prévios por sua alta eficiência para caupi (Vigna unguiculata, pode ser indicada para estudos de inoculação, visando a aumentar o rendimento dessa cultura em solos salinos. Os meios de cultura 79 e LB foram eficientes para avaliar a tolerância relativa de rizóbio a NaCl, mas o meio 79 é mais indicado, pois permite o crescimento de todas as estirpes. Pelos resultados, infere-se haver relação entre tolerância in vitro à salinidade e origem dos microssimbiontes, pois as estirpes BR 4007 e BR 6806, oriundas do Ceará, estiveram entre as mais tolerantes.Tolerance to salinity of diazotrophic bacteriaand their host species could increase plant growth and sustainability in salt stressed soils. Twelve diazotrophic bacteria strains were studied regarding their tolerance to different NaCl concentrations in 79 and LB media. More tolerant (30 g L-1 strains in 79 medium were: the fast growers BR 6806 and BR 4007, isolated from northeast Brazil, UFLA 03-51 and UFLA 03-65, and slow growing strain UFLA03-84, being these last three isolated from Amazon region. These strains were among

  20. Responses of enzymatic antioxidants and non-enzymatic antioxidants in the cyanobacterium Microcystis aeruginosa to the allelochemical ethyl 2-methyl acetoacetate (EMA) isolated from reed (Phragmites communis).

    Science.gov (United States)

    Hong, Yu; Hu, Hong-Ying; Xie, Xing; Li, Feng-Min

    2008-08-25

    Macrophytic allelochemicals are considered an environment-friendly and promising alternative to control algal bloom. However, studies examining the potential mechanisms of inhibitory allelochemicals on algae are few. The allelochemical ethyl 2-methyl acetoacetate (EMA), isolated from reed (Phragmites communis), was a strong allelopathic inhibitor on the growth of Microcystis aeruginosa. EMA-induced antioxidant responses were investigated in the cyanobacterium M. aeruginosa to understand the mechanism of EMA inhibition on algal growth. The activities of enzymatic antioxidants superoxide dismutase (SOD) and catalase (CAT), and the contents of non-enzymatic antioxidants reduced glutathione (GSH) and ascorbic acid (AsA) of M. aeruginosa cells were analyzed after treatments with different concentrations of EMA. Exposure of M. aeruginosa to EMA caused changes in enzyme activities and contents of non-enzymatic antioxidants in different manners. The decrease in SOD activity occurred first after 4 h of EMA exposure, and more markedly after 40 h. CAT activity did not change after 4 h of EMA exposure, but increased obviously after 40 h. The contents of AsA and GSH were increased greatly by EMA after 4 h. After 60 h, low EMA concentrations still increased the CAT activity and the contents of AsA and GSH, but high EMA concentrations started to impose a marked suppression on them. EMA increased dehydroascorbate (DHAsA) and oxidized glutathione (GSSG) contents during all exposure times. After 60 h, the regeneration rates of AsA and GSH (represented by the AsA/DHAsA ratio and GSH/GSSG ratio, respectively) were reduced by high EMA concentrations. These results suggest that the activation of CAT and the availability of AsA and GSH at early exposure are important to counteract the oxidative stress induced by EMA, and the inactivation of SOD may be crucial to the growth inhibition of M. aeruginosa by EMA.

  1. Regulation of the carbon-concentrating mechanism in the cyanobacterium Synechocystis sp. PCC6803 in response to changing light intensity and inorganic carbon availability.

    Science.gov (United States)

    Burnap, Robert L; Nambudiri, Rehka; Holland, Steven

    2013-11-01

    Photosynthetic organisms possess regulatory mechanisms to balance the various inputs of photosynthesis in a manner that minimizes over-excitation of the light-driven electron transfer apparatus, while maximizing the reductive assimilation of inorganic nutrients, most importantly inorganic carbon (Ci). Accordingly, the regulatory interactions coordinating responses to fluctuating light and responses to Ci availability are of fundamental significance. The inducible high affinity carbon-concentrating mechanism (CCM) in the cyanobacterium Synechocystis sp. PCC6803 has been studied in order to understand how it is integrated with the light and dark reactions of photosynthesis. To probe genetic regulatory mechanisms, genomic DNA microarrays were used to survey for differences in the expression of genes in response to a shift to high light conditions under conditions of either high or low Ci availability. Discrepancies in published experiments exist regarding the extent to which genes for the CCM are upregulated in response to high light treatment. These discrepancies may be due to critical differences in Ci availability existing during the different high light experiments. The present microarray experiments reexamine this by comparing high light treatment under two different Ci regimes: bubbling with air and bubbling with air enriched with CO2. While some transcriptional responses such as the downregulation of antenna proteins are quite similar, pronounced differences exist with respect to the differential expression of CCM and affiliated genes. The results are discussed in the context of a recent analysis revealing that small molecules that are intermediates of the light and dark reaction photosynthetic metabolism act as allosteric effectors of the DNA-binding proteins which modulate the expression of the CCM genes.

  2. Mutagenesis of hetR reveals amino acids necessary for HetR function in the heterocystous cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Risser, Douglas D; Callahan, Sean M

    2007-03-01

    HetR is the master regulator of heterocyst differentiation in the filamentous cyanobacterium Anabaena sp. strain PCC 7120. Genetic selection was used to identify 33 amino acid substitutions in HetR that reduced the proportion of cells undergoing heterocyst differentiation to less than 2%. Conservative substitutions in the wild-type HetR protein revealed three mutations that dramatically reduced the amount of heterocyst differentiation when the mutant allele was present in place of the wild-type allele on a replicating plasmid in a mutant lacking hetR on the chromosome. An H69Y substitution resulted in heterocyst formation among less than 0.1% of cells, and D17E and G36A substitutions resulted in a Het- phenotype, compared to heterocyst formation among approximately 25% of cells with the wild-type hetR under the same conditions. The D17E substitution prevented DNA binding activity exhibited by wild-type HetR in mobility shift assays, whereas G36A and H69Y substitutions had no affect on DNA binding. D17E, G36A, and H69Y substitutions also resulted in higher levels of the corresponding HetR protein than of the wild-type protein when each was expressed from an inducible promoter in a hetR deletion strain, suggesting an effect on HetR protein turnover. Surprisingly, C48A and S152A substitutions, which were previously reported to result in a Het- phenotype, were found to have no effect on heterocyst differentiation or patterning when the corresponding mutations were introduced into an otherwise wild-type genetic background in Anabaena sp. strain PCC 7120. The clustering of mutations that satisfied the positive selection near the amino terminus suggests an important role for this part of the protein in HetR function.

  3. Growth inhibition of bloom forming cyanobacterium Microcystis aeruginosa by green route fabricated copper oxide nanoparticles.

    Science.gov (United States)

    Sankar, Renu; Prasath, Barathan Balaji; Nandakumar, Ravichandran; Santhanam, Perumal; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

    2014-12-01

    The cyanobacterium Microcystis aeruginosa can potentially proliferate in a wide range of freshwater bionetworks and create extensive secondary metabolites which are harmful to human and animal health. The M. aeruginosa release toxic microcystins that can create a wide range of health-related issues to aquatic animals and humans. It is essential to eliminate them from the ecosystem with convenient method. It has been reported that engineered metal nanoparticles are potentially toxic to pathogenic organisms. In the present study, we examined the growth inhibition effect of green synthesized copper oxide nanoparticles against M. aeruginosa. The green synthesized copper oxide nanoparticles exhibit an excitation of surface plasmon resonance (SPR) at 270 nm confirmed using UV-visible spectrophotometer. The dynamic light scattering (DLS) analysis revealed that synthesized nanoparticles are colloidal in nature and having a particle size of 551 nm with high stability at -26.6 mV. The scanning electron microscopy (SEM) analysis shows that copper oxide nanoparticles are spherical, rod and irregular in shape, and consistently distributed throughout the solution. The elemental copper and oxide peak were confirmed using energy dispersive x-ray analysis (EDAX). Fourier-transform infrared (FT-IR) spectroscopy indicates the presence of functional groups which is mandatory for the reduction of copper ions. Besides, green synthesized copper oxide nanoparticles shows growth inhibition against M. aeruginosa. The inhibition efficiency was 31.8 % at lower concentration and 89.7 % at higher concentration of copper oxide nanoparticles, respectively. The chlorophyll (a and b) and carotenoid content of M. aeruginosa declined in dose-dependent manner with respect to induction of copper oxide nanoparticles. Furthermore, we analyzed the mechanism behind the cytotoxicity of M. aeruginosa induced by copper oxide nanoparticles through evaluating membrane integrity, reactive oxygen species (ROS

  4. Thermostability of photosystem I trimers and monomers from the cyanobacterium Thermosynechococcus elongatus

    Science.gov (United States)

    Shubin, Vladimir V.; Terekhova, Irina V.; Bolychevtseva, Yulia V.; El-Mohsnawy, Eithar; Rögner, Matthias; Mäntele, Werner; Kopczak, Marta J.; Džafić, Enela

    2017-05-01

    The performance of solar energy conversion into alternative energy sources in artificial systems highly depends on the thermostability of photosystem I (PSI) complexes Terasaki et al. (2007), Iwuchukwu et al. (2010), Kothe et al. (2013) . To assess the thermostability of PSI complexes from the thermophilic cyanobacterium Thermosynechococcus elongatus heating induced perturbations on the level of secondary structure of the proteins were studied. Changes were monitored by Fourier transform infrared (FT-IR) spectra in the mid-IR region upon slow heating (1 °C per minute) of samples in D2O phosphate buffer (pD 7.4) from 20 °C to 100 °C. These spectra showed distinct changes in the Amide I region of PSI complexes as a function of the rising temperature. Absorbance at the Amide I maximum of PSI monomers (centered around 1653 cm- 1), gradually dropped in two temperature intervals, i.e. 60-75 and 80-90 °C. In contrast, absorbance at the Amide I maximum of PSI trimers (around 1656 cm- 1) dropped only in one temperature interval 80-95 °C. The thermal profile of the spectral shift of α-helices bands in the region 1656-1642 cm- 1 confirms the same two temperature intervals for PSI monomers and only one interval for trimers. Apparently, the observed absorbance changes at the Amide I maximum during heating of PSI monomers and trimers are caused by deformation and unfolding of α-helices. The absence of absorbance changes in the interval of 20-65 °C in PSI trimers is probably caused by a greater stability of protein secondary structure as compared to that in monomers. Upon heating above 80 °C a large part of α-helices both in trimers and monomers converts to unordered and aggregated structures. Spectral changes of PSI trimers and monomers heated up to 100 °C are irreversible due to protein denaturation and non-specific aggregation of complexes leading to new absorption bands at 1618-1620 cm- 1. We propose that monomers shield the denaturation sensitive sides at the

  5. Transcription and Regulation of the Bidirectional Hydrogenase in the Cyanobacterium Nostoc sp. Strain PCC 7120▿

    Science.gov (United States)

    Sjöholm, Johannes; Oliveira, Paulo; Lindblad, Peter

    2007-01-01

    The filamentous, heterocystous cyanobacterium Nostoc sp. strain PCC 7120 (Anabaena sp. strain PCC 7120) possesses an uptake hydrogenase and a bidirectional enzyme, the latter being capable of catalyzing both H2 production and evolution. The completely sequenced genome of Nostoc sp. strain PCC 7120 reveals that the five structural genes encoding the bidirectional hydrogenase (hoxEFUYH) are separated in two clusters at a distance of approximately 8.8 kb. The transcription of the hox genes was examined under nitrogen-fixing conditions, and the results demonstrate that the cluster containing hoxE and hoxF can be transcribed as one polycistronic unit together with the open reading frame alr0750. The second cluster, containing hoxU, hoxY, and hoxH, is transcribed together with alr0763 and alr0765, located between the hox genes. Moreover, alr0760 and alr0761 form an additional larger operon. Nevertheless, Northern blot hybridizations revealed a rather complex transcription pattern in which the different hox genes are expressed differently. Transcriptional start points (TSPs) were identified 66 and 57 bp upstream from the start codon of alr0750 and hoxU, respectively. The transcriptions of the two clusters containing the hox genes are both induced under anaerobic conditions concomitantly with the induction of a higher level of hydrogenase activity. An additional TSP, within the annotated alr0760, 244 bp downstream from the suggested translation start codon, was identified. Electrophoretic mobility shift assays with purified LexA from Nostoc sp. strain PCC 7120 demonstrated specific interactions between the transcriptional regulator and both hox promoter regions. However, when LexA from Synechocystis sp. strain PCC 6803 was used, the purified protein interacted only with the promoter region of the alr0750-hoxE-hoxF operon. A search of the whole Nostoc sp. strain PCC 7120 genome demonstrated the presence of 216 putative LexA binding sites in total, including recA and rec

  6. [Imported histoplasmosis].

    Science.gov (United States)

    Stete, Katarina; Kern, Winfried V; Rieg, Siegbert; Serr, Annerose; Maurer, Christian; Tintelnot, Kathrin; Wagner, Dirk

    2015-06-01

    Infections with Histoplasma capsulatum are rare in Germany, and mostly imported from endemic areas. Infections can present as localized or disseminated diseases in immunocompromised as well as immunocompetent hosts. A travel history may be a major clue for diagnosing histoplasmosis. Diagnostic tools include histology, cultural and molecular detection as well as serology. Here we present four cases of patients diagnosed and treated in Freiburg between 2004 and 2013 that demonstrate the broad range of clinical manifestations of histoplasmosis: an immunocompetent patient with chronic basal meningitis; a patient with HIV infection and fatal disseminated disease; a patient with pulmonary and cutaneous disease and mediastinal and cervical lymphadenopathy; and an immunosuppressed patient with disseminated involvement of lung, bone marrow and adrenal glands.

  7. Proteomic and cellular views of Arthrospira sp. PCC 8005 adaptation to nitrogen depletion.

    Science.gov (United States)

    Deschoenmaeker, Frédéric; Facchini, Raphaël; Leroy, Baptiste; Badri, Hanène; Zhang, C-C; Wattiez, Ruddy

    2014-06-01

    Cyanobacteria are photosynthetic prokaryotes that play a crucial role in the Earth's nitrogen and carbon cycles. Nitrogen availability is one of the most important factors in cyanobacterial growth. Interestingly, filamentous non-diazotrophic cyanobacteria, such as Arthrospira sp. PCC 8005, have developed survival strategies that enable them to adapt to nitrogen deprivation. Metabolic studies recently demonstrated a substantial synthesis and accumulation of glycogen derived from amino acids during nitrogen starvation. Nevertheless, the regulatory mechanism of this adaptation is poorly understood. To the best of our knowledge, this study is the first proteomic and cellular analysis of Arthrospira sp. PCC 8005 under nitrogen depletion. Label-free differential proteomic analysis indicated the global carbon and nitrogen reprogramming of the cells during nitrogen depletion as characterized by an upregulation of glycogen synthesis and the use of endogenous nitrogen sources. The degradation of proteins and cyanophycin provided endogenous nitrogen when exogenous nitrogen was limited. Moreover, formamides, cyanates and urea were also potential endogenous nitrogen sources. The transporters of some amino acids and alternative nitrogen sources such as ammonium permease 1 were induced under nitrogen depletion. Intriguingly, although Arthrospira is a non-diazotrophic cyanobacterium, we observed the upregulation of HetR and HglK proteins, which are involved in heterocyst differentiation. Moreover, after a long period without nitrate, only a few highly fluorescent cells in each trichome were observed, and they might be involved in the long-term survival mechanism of this non-diazotrophic cyanobacterium under nitrogen deprivation.

  8. Isolation of Wheat Endophytic Diazotrophs and Determination of 1-Aminocyclopropane-1-Carboxylate Deaminase%小麦内生固氮菌分离及其ACC脱氨酶测定

    Institute of Scientific and Technical Information of China (English)

    秦宝军; 罗琼; 高淼; 胡海燕; 徐晶; 周义清; 孙建光

    2012-01-01

    [Objective ] The objective of this study is to determine the ammount of wheat endophytic diazotrophs and screen for ACC (1-aminocyclopropane-l-carboxylate) deaminase activity from the diazotrophs, determine the phylogenetic and classiflc position of selected strains and prepare strains for microbial fertilizer production. [ Method] Surface sterilization and nitrogen-free medium were used to isolate diazotroph and ACC was used as sole nitrogen source to screen strains with ACC deaminase activity. Nitrogenase activity was determined with acetylene reduction assay. 16S rDNA was amplified with PCR and analysed with MEGA software. Strain identification was carried out based on the morphology, physiology, biochemical test results and 16S rDNA analysis. [Result] The ammount of endophytic diazotrophs at jointing stage of wheat was (O.2-17.8)xlO* cfu-g"1 fresh weight Sixty endophytic diazotrophs with nitrogenase activity ranging 1-36 nmol QHt/h-mg protein were isolated from wheat. Nine of the 60 endophytic diazotrophs were ACC deaminase positive, the range of enzyme activity is 0.87-9.32 nmol a-ketobutryric acid/hmg protein. New isolate 9136 with nitrogenase activity 1.82 nmol C2Ei/h-mg protein and ACC deaminase activity 9.32 umol a-ketobutryric acid/h-mg protein was identified as Pseudomonas sp.. [Conclusion] About 10s cfu-g'1 (fresh weight) endophytic diazotrophs naturally colonized field grown wheat, some of these endophytic diazotrophs could produce ACC deaminase. A few strains showed relatively high ACC deaminase activity, and they might play a role in crop resistance to enviromental stress.%[目的]了解小麦内生固氮菌数量,筛选具有ACC(1-aminocyclopropane-1-carboxylate,1-氨基环丙烷-1-羧酸)脱氨酶活性的小麦内生固氮菌,确定筛选菌株的系统发育地位与分类地位,为微生物肥料生产收集菌种资源.[方法]样品表面灭菌后采用无氮培养法筛选内生固氮菌,乙炔还原法测定菌株固氮酶活性;采用ACC

  9. Stigonemapeptin, an Ahp-containing depsipeptide with elastase inhibitory activity from the bloom-forming freshwater cyanobacterium Stigonema sp.

    Science.gov (United States)

    Kang, Hahk-Soo; Krunic, Aleksej; Orjala, Jimmy

    2012-04-27

    Stigonemapeptin (1), a depsipeptide containing an Ahp (3-amino-6-hydroxy-2-piperidone) residue, was isolated from a bloom sample of the freshwater cyanobacterium Stigonema sp. collected from North Nokomis Lake in the Highland Lake District of northern Wisconsin. The planar structure was determined by 1D and 2D NMR experiments as well as HRESIMS analysis. The absolute configurations of the amino acids were determined using the advanced Marfey's method after acid hydrolysis. Stigonemapeptin (1), characterized by the presence of the Ahp residue, also contained the modified amino acids Abu (2-amino-2-butenoic acid) and N-formylated Pro. Stigonemapeptin (1) showed in vitro elastase and chymotrypsin inhibitory activity, with IC(50) values of 0.26 and 2.93 μM, respectively.

  10. Constitution and energetics of photosystem I and photosystem II in the chlorophyll d-dominated cyanobacterium Acaryochloris marina.

    Science.gov (United States)

    Tomo, Tatsuya; Allakhverdiev, Suleyman I; Mimuro, Mamoru

    2011-01-01

    This mini review presents current topics of discussion about photosystem (PS) I and PS II of photosynthesis in the Acaryochloris marina. A. marina is a photosynthetic cyanobacterium in which chlorophyll (Chl) d is the major antenna pigment (>95%). However, Chl a is always present in a few percent. Chl d absorbs light with a wavelength up to 30 nm red-shifted from Chl a. Therefore, the chlorophyll species of the special pair in PS II has been a matter of debate because if Chl d was the special pair component, the overall energetics must be different in A. marina. The history of this field indicates that a purified sample is necessary for the reliable identification and characterization of the special pair. In view of the spectroscopic data and the redox potential of pheophytin, we discuss the nature of special pair constituents and the localization of the enigmatic Chl a.

  11. Direct measurement of excitation transfer dynamics between two trimers in C-phycocyanin hexamer from cyanobacterium Anabaena variabilis

    Science.gov (United States)

    Zhang, Jingmin; Zhao, Fuli; Zheng, Xiguang; Wang, Hezhou

    1999-05-01

    We provide the first experimental evidence for the excitation transfers between two trimers of an isolated C-phycocyanin hexamer (αβ) 6PCL RC27, at the end of the rod proximal to the core of PBS in cyanobacterium of Anabaena variabilis, with picosecond time-resolved fluorescence spectroscopy. Our results strongly suggest that the observed fluorescence decay constants around 20 and 10 ps time scales, shown in anisotropy decay, not in isotropic decay experiments arose from the excitation transfers between two trimers via two types of transfer pathways such as 1β 155↔6β 155 (2β 155↔5β 155 and 3β 155↔4β 155) and 2α 84↔5α 84 (3α 84↔6α 84 and 1α 84↔4α 84) channels and these could be described by Föster dipole-dipole resonance mechanism.

  12. Requirement of Fra proteins for communication channels between cells in the filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Omairi-Nasser, Amin; Mariscal, Vicente; Austin, Jotham R; Haselkorn, Robert

    2015-08-11

    The filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 differentiates specialized cells, heterocysts, that fix atmospheric nitrogen and transfer the fixed nitrogen to adjacent vegetative cells. Reciprocally, vegetative cells transfer fixed carbon to heterocysts. Several routes have been described for metabolite exchange within the filament, one of which involves communicating channels that penetrate the septum between adjacent cells. Several fra gene mutants were isolated 25 y ago on the basis of their phenotypes: inability to fix nitrogen and fragmentation of filaments upon transfer from N+ to N- media. Cryopreservation combined with electron tomography were used to investigate the role of three fra gene products in channel formation. FraC and FraG are clearly involved in channel formation, whereas FraD has a minor part. Additionally, FraG was located close to the cytoplasmic membrane and in the heterocyst neck, using immunogold labeling with antibody raised to the N-terminal domain of the FraG protein.

  13. The leaves of green plants as well as a cyanobacterium, a red alga, and fungi contain insulin-like antigens

    Directory of Open Access Journals (Sweden)

    L.B. Silva

    2002-03-01

    Full Text Available We report the detection of insulin-like antigens in a large range of species utilizing a modified ELISA plate assay and Western blotting. We tested the leaves or aerial parts of species of Rhodophyta (red alga, Bryophyta (mosses, Psilophyta (whisk ferns, Lycopodophyta (club mosses, Sphenopsida (horsetails, gymnosperms, and angiosperms, including monocots and dicots. We also studied species of fungi and a cyanobacterium, Spirulina maxima. The wide distribution of insulin-like antigens, which in some cases present the same electrophoretic mobility as bovine insulin, together with results recently published by us on the amino acid sequence of an insulin isolated from the seed coat of jack bean (Canavalia ensiformis and from the developing fruits of cowpea (Vigna unguiculata, suggests that pathways depending on this hormone have been conserved through evolution.

  14. The leaves of green plants as well as a cyanobacterium, a red alga, and fungi contain insulin-like antigens.

    Science.gov (United States)

    Silva, L B; Santos, S S S; Azevedo, C R; Cruz, M A L; Venâncio, T M; Cavalcante, C P; Uchôa, A F; Astolfi Filho, S; Oliveira, A E A; Fernandes, K V S; Xavier-Filho, J

    2002-03-01

    We report the detection of insulin-like antigens in a large range of species utilizing a modified ELISA plate assay and Western blotting. We tested the leaves or aerial parts of species of Rhodophyta (red alga), Bryophyta (mosses), Psilophyta (whisk ferns), Lycopodophyta (club mosses), Sphenopsida (horsetails), gymnosperms, and angiosperms, including monocots and dicots. We also studied species of fungi and a cyanobacterium, Spirulina maxima. The wide distribution of insulin-like antigens, which in some cases present the same electrophoretic mobility as bovine insulin, together with results recently published by us on the amino acid sequence of an insulin isolated from the seed coat of jack bean (Canavalia ensiformis) and from the developing fruits of cowpea (Vigna unguiculata), suggests that pathways depending on this hormone have been conserved through evolution.

  15. Broad host range plasmid-based gene transfer system in the cyanobacterium Gloeobacter violaceus which lacks thylakoids

    Institute of Scientific and Technical Information of China (English)

    GUO Haitao; XU Xudong

    2004-01-01

    Gloeobacter violaceus, a cyanobacterium lack of thylakoids, is refractory to genetic manipulations because its cells are enveloped by a thick gelatinous sheath and in colonial form.In this study, a large number of single cells were obtained by repeated pumping with a syringe with the gelatinous sheath removed.And an exogenous broad host range plasmid pKT210 was conjugatively transferred into G.violaceus.Analyses with dot-blot hybridization and restriction mapping showed that the exogenous plasmid pKT210 had been introduced into G.violaceus and stably maintained with no alteration in its structure.pKT210 extracted from G.violaceus exconjugants could be transformed into the mcr- mrr- E.coli strain DH10B but not the mcr+ mrr+ strain DH5α, which suggests that a methylase system may be present in G.violaceus.

  16. Microenvironmental Ecology of the Chlorophyll b-containing Symbiotic Cyanobacterium Prochloron in the Didemnid Ascidian Lissoclinum patella

    Directory of Open Access Journals (Sweden)

    Michael eKühl

    2012-11-01

    Full Text Available The discovery of the cyanobacterium Prochloron was the first finding of a bacterial oxyphototroph with chlorophyll (Chl b, in addition to Chl a. It was first described as Prochloron didemni but a number of clades have since been described. Prochloron is a conspicuously large (7-25 µm unicellular cyanobacterium living in a symbiotic relationship, primarily with (sub- tropical didemnid ascidians; it has resisted numerous cultivation attempts and appears truly obligatory symbiotic. Recently, a Prochloron draft genome was published, revealing no lack of metabolic genes that could explain the apparent inability to reproduce and sustain photosynthesis in a free-living stage. Possibly, the unsuccessful cultivation is partly due to a lack of knowledge about the microenvironmental conditions and ecophysiology of Prochloron in its natural habitat. We used microsensors, variable chlorophyll fluorescence imaging and imaging of O2 and pH to obtain a detailed insight to the microenvironmental ecology and photobiology of Prochloron in hospite in the didemnid ascidian Lissoclinum patella. The microenvironment within ascidians is characterized by steep gradients of light and chemical parameters that change rapidly with varying irradiances. The interior zone of the ascidians harboring Prochloron thus became anoxic and acidic within a few min of darkness, while the same zone exhibited O2 super-saturation and strongly alkaline pH after a few min of illumination. Photosynthesis showed lack of photoinhibition even at high irradiances equivalent to full sunlight, and photosynthesis recovered rapidly after periods of anoxia. We discuss these new insights on the ecological niche of Prochloron and possible interactions with its host and other microbes in light of its recently published genome and a recent study of the overall microbial diversity and metagenome of L. patella.

  17. Global transcriptional responses of the toxic cyanobacterium, Microcystis aeruginosa, to nitrogen stress, phosphorus stress, and growth on organic matter.

    Directory of Open Access Journals (Sweden)

    Matthew J Harke

    Full Text Available Whole transcriptome shotgun sequencing (RNA-seq was used to assess the transcriptomic response of the toxic cyanobacterium Microcystis aeruginosa during growth with low levels of dissolved inorganic nitrogen (low N, low levels of dissolved inorganic phosphorus (low P, and in the presence of high levels of high molecular weight dissolved organic matter (HMWDOM. Under low N, one third of the genome was differentially expressed, with significant increases in transcripts observed among genes within the nir operon, urea transport genes (urtBCDE, and amino acid transporters while significant decreases in transcripts were observed in genes related to photosynthesis. There was also a significant decrease in the transcription of the microcystin synthetase gene set under low N and a significant decrease in microcystin content per Microcystis cell demonstrating that N supply influences cellular toxicity. Under low P, 27% of the genome was differentially expressed. The Pho regulon was induced leading to large increases in transcript levels of the alkaline phosphatase phoX, the Pst transport system (pstABC, and the sphX gene, and transcripts of multiple sulfate transporter were also significantly more abundant. While the transcriptional response to growth on HMWDOM was smaller (5-22% of genes differentially expressed, transcripts of multiple genes specifically associated with the transport and degradation of organic compounds were significantly more abundant within HMWDOM treatments and thus may be recruited by Microcystis to utilize these substrates. Collectively, these findings provide a comprehensive understanding of the nutritional physiology of this toxic, bloom-forming cyanobacterium and the role of N in controlling microcystin synthesis.

  18. Global transcriptional responses of the toxic cyanobacterium, Microcystis aeruginosa, to nitrogen stress, phosphorus stress, and growth on organic matter.

    Science.gov (United States)

    Harke, Matthew J; Gobler, Christopher J

    2013-01-01

    Whole transcriptome shotgun sequencing (RNA-seq) was used to assess the transcriptomic response of the toxic cyanobacterium Microcystis aeruginosa during growth with low levels of dissolved inorganic nitrogen (low N), low levels of dissolved inorganic phosphorus (low P), and in the presence of high levels of high molecular weight dissolved organic matter (HMWDOM). Under low N, one third of the genome was differentially expressed, with significant increases in transcripts observed among genes within the nir operon, urea transport genes (urtBCDE), and amino acid transporters while significant decreases in transcripts were observed in genes related to photosynthesis. There was also a significant decrease in the transcription of the microcystin synthetase gene set under low N and a significant decrease in microcystin content per Microcystis cell demonstrating that N supply influences cellular toxicity. Under low P, 27% of the genome was differentially expressed. The Pho regulon was induced leading to large increases in transcript levels of the alkaline phosphatase phoX, the Pst transport system (pstABC), and the sphX gene, and transcripts of multiple sulfate transporter were also significantly more abundant. While the transcriptional response to growth on HMWDOM was smaller (5-22% of genes differentially expressed), transcripts of multiple genes specifically associated with the transport and degradation of organic compounds were significantly more abundant within HMWDOM treatments and thus may be recruited by Microcystis to utilize these substrates. Collectively, these findings provide a comprehensive understanding of the nutritional physiology of this toxic, bloom-forming cyanobacterium and the role of N in controlling microcystin synthesis.

  19. Photosystem Trap Energies and Spectrally-Dependent Energy-Storage Efficiencies in the Chl d-Utilizing Cyanobacterium, Acaryochloris Marina

    Science.gov (United States)

    Mielke, Steven P.; Kiang, Nancy Y.; Blankenship, Robert E.; Mauzerall, David

    2012-01-01

    Acaryochloris marina is the only species known to utilize chlorophyll (Chl) d as a principal photopigment. The peak absorption wavelength of Chl d is redshifted approx. 40 nm in vivo relative to Chl a, enabling this cyanobacterium to perform oxygenic phototrophy in niche environments enhanced in far-red light. We present measurements of the in vivo energy-storage (E-S) efficiency of photosynthesis in A. marina, obtained using pulsed photoacoustics (PA) over a 90-nm range of excitation wavelengths in the red and far-red. Together with modeling results, these measurements provide the first direct observation of the trap energies of PSI and PSII, and also the photosystem-specific contributions to the total E-S efficiency. We find the maximum observed efficiency in A. marina (40+/-1% at 735 nm) is higher than in the Chl a cyanobacterium Synechococcus leopoliensis (35+/-1% at 690 nm). The efficiency at peak absorption wavelength is also higher in A. marina (36+/-1% at 710 nm vs. 31+/-1% at 670 nm). In both species, the trap efficiencies are approx. 40% (PSI) and approx. 30% (PSII). The PSI trap in A. marina is found to lie at 740+/-5 nm, in agreement with the value inferred from spectroscopic methods. The best fit of the model to the PA data identifies the PSII trap at 723+/-3 nm, supporting the view that the primary electron-donor is Chl d, probably at the accessory (ChlD1) site. A decrease in efficiency beyond the trap wavelength, consistent with uphill energy transfer, is clearly observed and fit by the model. These results demonstrate that the E-S efficiency in A. marina is not thermodynamically limited, suggesting that oxygenic photosynthesis is viable in even redder light environments.

  20. Microenvironmental Ecology of the Chlorophyll b-Containing Symbiotic Cyanobacterium Prochloron in the Didemnid Ascidian Lissoclinum patella.

    Science.gov (United States)

    Kühl, Michael; Behrendt, Lars; Trampe, Erik; Qvortrup, Klaus; Schreiber, Ulrich; Borisov, Sergey M; Klimant, Ingo; Larkum, Anthony W D

    2012-01-01

    The discovery of the cyanobacterium Prochloron was the first finding of a bacterial oxyphototroph with chlorophyll (Chl) b, in addition to Chl a. It was first described as Prochloron didemni but a number of clades have since been described. Prochloron is a conspicuously large (7-25 μm) unicellular cyanobacterium living in a symbiotic relationship, primarily with (sub-) tropical didemnid ascidians; it has resisted numerous cultivation attempts and appears truly obligatory symbiotic. Recently, a Prochloron draft genome was published, revealing no lack of metabolic genes that could explain the apparent inability to reproduce and sustain photosynthesis in a free-living stage. Possibly, the unsuccessful cultivation is partly due to a lack of knowledge about the microenvironmental conditions and ecophysiology of Prochloron in its natural habitat. We used microsensors, variable chlorophyll fluorescence imaging and imaging of O(2) and pH to obtain a detailed insight to the microenvironmental ecology and photobiology of Prochloron in hospite in the didemnid ascidian Lissoclinum patella. The microenvironment within ascidians is characterized by steep gradients of light and chemical parameters that change rapidly with varying irradiances. The interior zone of the ascidians harboring Prochloron thus became anoxic and acidic within a few minutes of darkness, while the same zone exhibited O(2) super-saturation and strongly alkaline pH after a few minutes of illumination. Photosynthesis showed lack of photoinhibition even at high irradiances equivalent to full sunlight, and photosynthesis recovered rapidly after periods of anoxia. We discuss these new insights on the ecological niche of Prochloron and possible interactions with its host and other microbes in light of its recently published genome and a recent study of the overall microbial diversity and metagenome of L. patella.

  1. Changes in gene expression, cell physiology and toxicity of the harmful cyanobacterium Microcystis aeruginosa at elevated CO2

    Directory of Open Access Journals (Sweden)

    Giovanni eSandrini

    2015-05-01

    Full Text Available Rising CO2 concentrations may have large effects on aquatic microorganisms. In this study, we investigated how elevated pCO2 affects the harmful freshwater cyanobacterium Microcystis aeruginosa. This species is capable of producing dense blooms and hepatotoxins called microcystins. Strain PCC 7806 was cultured in chemostats that were shifted from low to high pCO2 conditions. This resulted in a transition from a C-limited to a light-limited steady state, with a ~2.7 fold increase of the cyanobacterial biomass and ~2.5 fold more microcystin per cell. Cells increased their chlorophyll a and phycocyanin content, and raised their PSI/PSII ratio at high pCO2. Surprisingly, cells had a lower dry weight and contained less carbohydrates, which might be an adaptation to improve the buoyancy of Microcystis when light becomes more limiting at high pCO2. Only 234 of the 4,691 genes responded to elevated pCO2. For instance, expression of the carboxysome, RuBisCO, photosystem and C metabolism genes did not change significantly, and only a few N assimilation genes were expressed differently. The lack of large-scale changes in the transcriptome could suit a buoyant species that lives in eutrophic lakes with strong CO2 fluctuations very well. However, we found major responses in inorganic carbon uptake. At low pCO2, cells were mainly dependent on bicarbonate uptake, whereas at high pCO2 gene expression of the bicarbonate uptake systems was down-regulated and cells shifted to CO2 and low-affinity bicarbonate uptake. These results show that the need for high-affinity bicarbonate uptake systems ceases at elevated CO2. Moreover, the combination of an increased cyanobacterial abundance, improved buoyancy, and higher toxin content per cell indicates that rising atmospheric CO2 levels may increase the problems associated with the harmful cyanobacterium Microcystis in eutrophic lakes.

  2. Proteomic strategy for the analysis of the polychlorobiphenyl-degrading cyanobacterium Anabaena PD-1 exposed to Aroclor 1254.

    Directory of Open Access Journals (Sweden)

    Hangjun Zhang

    Full Text Available The cyanobacterium Anabaena PD-1, which was originally isolated from polychlorobiphenyl (PCB-contaminated paddy soils, has capabilities for dechlorinatin and for degrading the commercial PCB mixture Aroclor 1254. In this study, 25 upregulated proteins were identified using 2D electrophoresis (2-DE coupled with matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS. These proteins were involved in (i PCB degradation (i.e., 3-chlorobenzoate-3,4-dioxygenase; (ii transport processes [e.g., ATP-binding cassette (ABC transporter substrate-binding protein, amino acid ABC transporter substrate-binding protein, peptide ABC transporter substrate-binding protein, putrescine-binding protein, periplasmic solute-binding protein, branched-chain amino acid uptake periplasmic solute-binding protein, periplasmic phosphate-binding protein, phosphonate ABC transporter substrate-binding protein, and xylose ABC transporter substrate-binding protein]; (iii energetic metabolism (e.g., methanol/ethanol family pyrroloquinoline quinone (PQQ-dependent dehydrogenase, malate-CoA ligase subunit beta, enolase, ATP synthase β subunit, FOF1 ATP synthase subunit beta, ATP synthase α subunit, and IMP cyclohydrolase; (iv electron transport (cytochrome b6f complex Fe-S protein; (v general stress response (e.g., molecular chaperone DnaK, elongation factor G, and translation elongation factor thermostable; (vi carbon metabolism (methanol dehydrogenase and malate-CoA ligase subunit beta; and (vii nitrogen reductase (nitrous oxide reductase. The results of real-time polymerase chain reaction showed that the genes encoding for dioxygenase, ABC transporters, transmembrane proteins, electron transporter, and energetic metabolism proteins were significantly upregulated during PCB degradation. These genes upregulated by 1.26- to 8.98-fold. These findings reveal the resistance and adaptation of cyanobacterium to the presence of PCBs, shedding light on the

  3. Proteomic strategy for the analysis of the polychlorobiphenyl-degrading cyanobacterium Anabaena PD-1 exposed to Aroclor 1254.

    Science.gov (United States)

    Zhang, Hangjun; Jiang, Xiaojun; Xiao, Wenfeng; Lu, Liping

    2014-01-01

    The cyanobacterium Anabaena PD-1, which was originally isolated from polychlorobiphenyl (PCB)-contaminated paddy soils, has capabilities for dechlorinatin and for degrading the commercial PCB mixture Aroclor 1254. In this study, 25 upregulated proteins were identified using 2D electrophoresis (2-DE) coupled with matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). These proteins were involved in (i) PCB degradation (i.e., 3-chlorobenzoate-3,4-dioxygenase); (ii) transport processes [e.g., ATP-binding cassette (ABC) transporter substrate-binding protein, amino acid ABC transporter substrate-binding protein, peptide ABC transporter substrate-binding protein, putrescine-binding protein, periplasmic solute-binding protein, branched-chain amino acid uptake periplasmic solute-binding protein, periplasmic phosphate-binding protein, phosphonate ABC transporter substrate-binding protein, and xylose ABC transporter substrate-binding protein]; (iii) energetic metabolism (e.g., methanol/ethanol family pyrroloquinoline quinone (PQQ)-dependent dehydrogenase, malate-CoA ligase subunit beta, enolase, ATP synthase β subunit, FOF1 ATP synthase subunit beta, ATP synthase α subunit, and IMP cyclohydrolase); (iv) electron transport (cytochrome b6f complex Fe-S protein); (v) general stress response (e.g., molecular chaperone DnaK, elongation factor G, and translation elongation factor thermostable); (vi) carbon metabolism (methanol dehydrogenase and malate-CoA ligase subunit beta); and (vii) nitrogen reductase (nitrous oxide reductase). The results of real-time polymerase chain reaction showed that the genes encoding for dioxygenase, ABC transporters, transmembrane proteins, electron transporter, and energetic metabolism proteins were significantly upregulated during PCB degradation. These genes upregulated by 1.26- to 8.98-fold. These findings reveal the resistance and adaptation of cyanobacterium to the presence of PCBs, shedding light on the

  4. A putative O-linked β-N-acetylglucosamine transferase is essential for hormogonium development and motility in the filamentous cyanobacterium Nostoc punctiforme.

    Science.gov (United States)

    Khayatan, Behzad; Bains, Divleen K; Cheng, Monica H; Cho, Ye Won; Huynh, Jessica; Kim, Rachelle; Omoruyi, Osagie H; Pantoja, Adriana P; Park, Jun Sang; Peng, Julia K; Splitt, Samantha D; Tian, Mason Y; Risser, Douglas D

    2017-02-27

    Most species of filamentous cyanobacteria are capable of gliding motility, likely via a conserved type IV pilus-like system that may also secrete a motility associated polysaccharide. In a subset of these organisms, motility is only achieved after the transient differentiation of hormogonia, specialized filaments that enter a non-growth state dedicated to motility. Despite the fundamental importance of hormogonia to the life cycle of many filamentous cyanobacteria, the molecular regulation of hormogonium development is largely undefined. To systematically identify genes essential for hormogonium development and motility in the model heterocyst-forming, filamentous cyanobacterium Nostoc punctiforme, a forward genetic screen was employed. The first gene identified using this screen, designated ogtA, encodes a putative O-linked β-N-acetylglucosamine transferase (OGT). Deletion of ogtA abolished motility while ectopic expression of ogtA induced hormogonium development even under hormogonium-repressing conditions. Transcription of ogtA is rapidly upregulated (1 h) following hormogonium induction and an OgtA-GFPuv fusion protein localized to the cytoplasm. In developing hormogonia, accumulation of PilA, but not HmpD, is dependent on ogtA RT-qPCR analysis indicated equivalent levels of pilA transcript in the wild-type and ΔogtA strain, while a reporter construct consisting of the intergenic region 5' to pilA fused to gfp produced lower levels of fluorescence in the ΔogtA strain than the wild-type. Production of hormogonium polysaccharide in the ΔogtA strain is reduced compared to the wild type, but comparable to that of a pilA-deletion strain. Collectively, these results imply that O-GlcNAc protein modification regulates the accumulation of PilA via a post-transcriptional mechanism in developing hormogonia.Importance Filamentous cyanobacteria are among the most developmentally complex prokaryotes. Species such as Nostoc punctiforme develop an array of cell types

  5. Migration of endophytic diazotroph Azorhizobium caulinodans ORS571 inside wheat (Triticum aestivum L) and its effect on microRNAs.

    Science.gov (United States)

    Qiu, Li; Li, Qiang; Zhang, Junbiao; Chen, Yongchao; Lin, Xiaojun; Sun, Chao; Wang, Weiling; Liu, Huawei; Zhang, Baohong

    2017-05-01

    Azorhizobium caulinodans ORS571, a novel rhizobium, forms endosymbionts with its nature host Sesbania rostrata, a semi-aquatic leguminous tree. Recent studies showed that A. caulinodans ORS571, as endophytic rhizobium, disseminated and colonized inside of cereal plants. However, how this rhizobium infects monocot plants and the regulatory mechanism remains unknown. MicroRNAs (miRNAs) are small, endogenous RNAs that regulate gene expression at the post-transcriptional levels. In this study, we employed laser scanning confocal microscope to monitor the pathway that rhizobium invade wheat; we also investigated the potential role of miRNAs during A. caulinodans ORS571 infecting wheat. Our results showed that gfp-labeled A. caulinodans ORS571 infected wheat root hairs and emerged lateral roots, then disseminated and colonized within roots and migrated to other plant tissues, such as stems and leaves. Endophytic rhizobium induced the aberrant expression of miRNAs in wheat with a tissue- and time-dependent manner with a peak at 12-24 h after rhizobium infection. Some miRNAs, such as miR167 and miR393 responded more in roots than that in shoots. In contrast, miR171 responded higher in shoots than that in roots. These results suggested that miRNAs could be responsive to A. caulinodans ORS571 infection and played important role in plant growth, nutrient metabolisms, and wheat-rhizobium interactions.

  6. Diversidade de bactérias diazotróficas endofíticas associadas a plantas de milho Diversity of diazotrophic endophytic bacteria associated with maize plants

    Directory of Open Access Journals (Sweden)

    Luiz Fernando Wurdig Roesch

    2007-12-01

    capazes de colonizar o interior de plantas de milho e que as diferentes condições edafoclimáticas estão correlacionadas com a diversidade dos genes nifH.Endophytic diazotrophic bacteria are capable of promoting maize growth through biological nitrogen fixation (BNF or by the production of plant hormones. The aim of this study was to characterize diversity of endophytic bacteria in maize at sites with different climate and soil conditions in Rio Grande do Sul, Brazil. A PCR-RFLP approach and sequence analysis of nifH Cluster I clone libraries were used to assess diversity in maize plants. The Shannon-Weaver and Equitability indices were calculated to estimate the diazotroph diversity as well as the nucleotide diversity and the average sequence divergence to estimate genetic diversity. To evaluate the variability in populations we performed the F ST test. A greater variation in bacterial communities was detected between rather than within regions, particularly among communities of different soil types and varying water regimes and geographical regions. The Shannon-Weaver index indicated a high difference in terms of diversity of taxonomic units among the communities. The diversity of the communities in the northern region, with higher precipitation and clay content, tended to be higher than that in the south. The Equitability index indicated that there was a dominant taxonomic unit within each community. All clones grouped into nifH gene cluster I. The nifH sequence types from Alpha, Beta and Gammaproteobacteria were recovered. These results demonstrate that there is a large diversity of endophytic nitrogen-fixing bacteria able to colonize maize tissue and that nifH diversity is correlated with the different environmental conditions.

  7. Significant N₂ fixation by heterotrophs, photoheterotrophs and heterocystous cyanobacteria in two temperate estuaries.

    Science.gov (United States)

    Bentzon-Tilia, Mikkel; Traving, Sachia J; Mantikci, Mustafa; Knudsen-Leerbeck, Helle; Hansen, Jørgen L S; Markager, Stiig; Riemann, Lasse

    2015-02-01

    Nitrogen (N) fixation is fueling planktonic production in a multitude of aquatic environments. In meso- and poly-haline estuaries, however, the contribution of N by pelagic N₂ fixation is believed to be