Hydrogen Production by the Unicellular, Diazotrophic Cyanobacterium Cyanothece sp. Strain ATCC 51142 under Conditions of Continuous Light

ABSTRACT We report on the hydrogen production properties of the unicellular, diazotrophic cyanobacterium Cyanothece sp. strain ATCC 51142. This organism has a versatile metabolism and can grow in the presence or absence of combined nitrogen and can grow photosynthetically or mixotrophically and heterotrophically in the presence of glycerol. The strain produces a bidirectional hydrogenase (encoded by the hox genes), an uptake hydrogenase (hupLS), and nitrogenase (nifHDK). We demonstrated hydrogen production by both the hydrogenase and the nitrogenase under appropriate metabolic conditions. The highest rates of hydrogen production were produced under nitrogen-fixing conditions when cells were grown and incubated under continuous light conditions, in either the presence or absence of glycerol. Under such nitrogen-fixing conditions, we have achieved rates of 300 μmol H2/mg chloramphenicol (Chl)/hr during the first 24 h of incubation. The levels of H2 measured were dependent upon the incubation conditions, such as sparging with argon, which generated anaerobic conditions. We demonstrated that the same conditions led to high levels of H2 production and N2 fixation, indicating that low-oxygen conditions favor nitrogenase activity for both processes. The levels of hydrogen produced by the hydrogenase are much lower, typically 5 to 10 μmol H2/mg Chl/hr. Hydrogenase activity was dependent upon electron transport through photosystem II (PS II), whereas nitrogenase activity was more dependent on PS I, as well as on respiration. Although cells do not double under the incubation conditions when sparged with argon to provide a low-oxygen environment, the cells are metabolically active, and hydrogen production can be inhibited by the addition of chloramphenicol to inhibit protein synthesis.

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New marine nitrogen-fixing bacteria isolated from an eelgrass (Zostera marina) bed

Canadian Journal of Microbiology ◽

10.1139/m88-153 ◽

1988 ◽

Vol 34 (7) ◽

pp. 886-890 ◽

Cited By ~ 6

Author(s):

Wung Yang Shieh ◽

Usio Simidu ◽

Yoshiharu Maruyama

Keyword(s):

Zostera Marina ◽

Nitrogenase Activity ◽

Molecular Nitrogen ◽

Exponential Growth Phase ◽

Nitrogen Fixing ◽

Low Oxygen ◽

Nitrogen Fixing Bacteria ◽

Nitrogen Fixation Activity ◽

The Family ◽

Ph Decrease

Four strains of marine nitrogen-fixing bacteria were isolated from the roots of eelgrass (Zostera marina) and from sediments in an eelgrass bed in Aburatsubo Inlet, Kanagawa Prefecture, Japan. Significant levels of nitrogenase activity were detected in all four strains after a few hours of incubation under anaerobic conditions. Nitrogenase activity in all cases was Na+ dependent. These strains grew anaerobically or under conditions of low oxygen, using molecular nitrogen as the sole nitrogen source. Bacterial growth in liquid nitrogen-free medium was accompanied by a marked pH decrease during the exponential growth phase. Neither yeast extract nor vitamins were required for the nitrogen fixation activity of these strains. Taxonomically, all strains were facultatively anaerobic, Gram-negative rods. They were motile in liquid medium by means of a single polar flagellum and required NaCl for their growth. These characteristics, as well as the guanine + cytosine content of their DNA (43.5 – 44.8 mol%), placed them in the family Vibrionaceae. These strains, however, could not be identified to the genus level because they were distinct from the two halophilic genera Vibrio and Photobacterium of the family Vibrionaceae by a variety of characteristics.

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Hydrogen Evolution Catalyzed by Hydrogenase in Cultures of Cyanobacteria

Zeitschrift für Naturforschung C ◽

10.1515/znc-1981-1-217 ◽

1981 ◽

Vol 36 (1-2) ◽

pp. 87-92 ◽

Cited By ~ 14

Author(s):

Patrick C. Hallenbeck ◽

Leon V. Kochian ◽

John R. Benemann

Keyword(s):

Hydrogen Production ◽

Hydrogen Evolution ◽

High Frequency ◽

Nitrogenase Activity ◽

Inhibitory Effect ◽

Hydrogenase Activity ◽

Oxygen Inhibition ◽

Oxygen Sensitive

Abstract Cultures of Anabaena cylindrica, grown on media containing 5 mᴍ NH4Cl (which represses heterocyst formation), evolved hydrogen after a period of dark incubation under an argon atmosphere. This hydrogen production was not due to nitrogenase activity, which was nearly undetectable, but was due to a hydrogenase. Cultures grown on media with tungsten substituted for molybdenum had a high frequency of heterocysts (15%) and inactive nitrogenase after nitrogen starvation. The hydrogenase activity of these cultures was three-fold greater than the activity of non-heterocystous cultures. The effects of oxygen inhibition on hydrogen evolution by hetero-cystous cultures suggest that two pools of hydrogenase activity exist - an oxygen sensitive hydrogen evolution in vegetative cells and a relatively oxygen-resistent hydrogen evolution in heterocysts. In either case, inhibition by oxygen was reversible. Light had an inhibitory effect on net hydrogen evolution. Hydrogen production in vitro was much higher than in vivo, indicating that in vivo hydrogenase activity is limited by endogenous reductant supply.

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Gene expression under low-oxygen conditions in the cyanobacterium Synechocystis sp. PCC 6803 demonstrates Hik31-dependent and -independent responses

Microbiology ◽

10.1099/mic.0.041053-0 ◽

2011 ◽

Vol 157 (2) ◽

pp. 301-312 ◽

Cited By ~ 25

Author(s):

Tina C. Summerfield ◽

Sowmya Nagarajan ◽

Louis A. Sherman

Keyword(s):

Ribosomal Proteins ◽

Chlorophyll Biosynthesis ◽

Large Set ◽

Wild Type ◽

Low Oxygen ◽

Knockout Mutant ◽

Gene Encoding ◽

Ps Ii ◽

Oxygen Conditions ◽

Pcc 6803

We have investigated the response of the cyanobacterium Synechocystis sp. PCC 6803 during growth at very low O2 concentration (bubbled with 99.9 % N2/0.1 % CO2). Significant transcriptional changes upon low-O2 incubation included upregulation of a cluster of genes that contained psbA1 and an operon that includes a gene encoding the two-component regulatory histidine kinase, Hik31. This regulatory cluster is of particular interest, since there are virtually identical copies on both the chromosome and plasmid pSYSX. We used a knockout mutant lacking the chromosomal copy of hik31 and studied differential transcription during the aerobic–low-O2 transition in this ΔHik31 strain and the wild-type. We observed two distinct responses to this transition, one Hik31 dependent, the other Hik31 independent. The Hik31-independent responses included the psbA1 induction and genes involved in chlorophyll biosynthesis. In addition, there were changes in a number of genes that may be involved in assembling or stabilizing photosystem (PS)II, and the hox operon and the LexA-like protein (Sll1626) were upregulated during low-O2 growth. This family of responses mostly focused on PSII and overall redox control. There was also a large set of genes that responded differently in the absence of the chromosomal Hik31. In the vast majority of these cases, Hik31 functioned as a repressor and transcription was enhanced when Hik31 was deleted. Genes in this category encoded both core and peripheral proteins for PSI and PSII, the main phycobilisome proteins, chaperones, the ATP synthase cluster and virtually all of the ribosomal proteins. These findings, coupled with the fact that ΔHik31 grew better than the wild-type under low-O2 conditions, suggested that Hik31 helps to regulate growth and overall cellular homeostasis. We detected changes in the transcription of other regulatory genes that may compensate for the loss of Hik31. We conclude that Hik31 regulates an important series of genes that relate to energy production and growth and that help to determine how Synechocystis responds to changes in O2 conditions.

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Dinitrogenase-Driven Photobiological Hydrogen Production Combats Oxidative Stress in Cyanothece sp. Strain ATCC 51142

Applied and Environmental Microbiology ◽

10.1128/aem.02098-16 ◽

2016 ◽

Vol 82 (24) ◽

pp. 7227-7235 ◽

Cited By ~ 8

Author(s):

Natalie C. Sadler ◽

Hans C. Bernstein ◽

Matthew R. Melnicki ◽

Moiz A. Charania ◽

Eric A. Hill ◽

...

Keyword(s):

Oxidative Stress ◽

Hydrogen Production ◽

System Level ◽

Oxygenic Photosynthesis ◽

Hydrogenase Activity ◽

Enzyme Complex ◽

Strain Atcc ◽

Content Type ◽

Thiol Redox

ABSTRACTPhotobiologically synthesized hydrogen (H2) gas is carbon neutral to produce and clean to combust, making it an ideal biofuel.Cyanothecesp. strain ATCC 51142 is a cyanobacterium capable of performing simultaneous oxygenic photosynthesis and H2production, a highly perplexing phenomenon because H2evolving enzymes are O2sensitive. We employed a system-levelin vivochemoproteomic profiling approach to explore the cellular dynamics of protein thiol redox and how thiol redox mediates the function of the dinitrogenase NifHDK, an enzyme complex capable of aerobic hydrogenase activity. We found that NifHDK responds to intracellular redox conditions and may act as an emergency electron valve to prevent harmful reactive oxygen species formation in concert with other cell strategies for maintaining redox homeostasis. These results provide new insight into cellular redox dynamics useful for advancing photolytic bioenergy technology and reveal a new understanding for the biological function of NifHDK.IMPORTANCEHere, we demonstrate that high levels of hydrogen synthesis can be induced as a protection mechanism against oxidative stress via the dinitrogenase enzyme complex inCyanothecesp. strain ATCC 51142. This is a previously unknown feature of cyanobacterial dinitrogenase, and we anticipate that it may represent a strategy to exploit cyanobacteria for efficient and scalable hydrogen production. We utilized a chemoproteomic approach to capture thein situdynamics of reductant partitioning within the cell, revealing proteins and reactive thiols that may be involved in redox sensing and signaling. Additionally, this method is widely applicable across biological systems to achieve a greater understanding of how cells navigate their environment and how redox chemistry can be utilized to alter metabolism and achieve homeostasis.

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FixJ: a Major Regulator of the Oxygen Limitation Response and Late Symbiotic Functions of Sinorhizobium meliloti

Journal of Bacteriology ◽

10.1128/jb.00251-06 ◽

2006 ◽

Vol 188 (13) ◽

pp. 4890-4902 ◽

Cited By ~ 106

Author(s):

Christine Bobik ◽

Eliane Meilhoc ◽

Jacques Batut

Keyword(s):

Sinorhizobium Meliloti ◽

Expression Profiles ◽

Gene Expression Profiles ◽

Regulatory System ◽

Polyamine Metabolism ◽

Nitrogen Fixing ◽

Low Oxygen ◽

Free Living ◽

Expression Of Genes ◽

Oxygen Conditions

ABSTRACT Sinorhizobium meliloti exists either in a free-living state in the soil or in symbiosis within legume nodules, where the bacteria differentiate into nitrogen-fixing bacteroids. Expression of genes involved in nitrogen fixation and associated respiration is governed by two intermediate regulators, NifA and FixK, respectively, which are controlled by a two-component regulatory system FixLJ in response to low-oxygen conditions. In order to identify the FixLJ regulon, gene expression profiles were determined in microaerobic free-living cells as well as during the symbiotic life of the bacterium for the wild type and a fixJ null-mutant strain. We identified 122 genes activated by FixJ in either state, including 87 novel targets. FixJ controls 74% of the genes induced in microaerobiosis (2% oxygen) and the majority of genes expressed in mature bacteroids. Ninety-seven percent of FixJ-activated genes are located on the symbiotic plasmid pSymA. Transcriptome profiles of a nifA and a fixK mutant showed that NifA activates a limited number of genes, all specific to the symbiotic state, whereas FixK controls more than 90 genes, involved in free-living and/or symbiotic life. This study also revealed that FixJ has no other direct targets besides those already known. FixJ is involved in the regulation of functions such as denitrification or amino acid/polyamine metabolism and transport. Mutations in selected novel FixJ targets did not affect the ability of the bacteria to form nitrogen-fixing nodules on Medicago sativa roots. From these results, we propose an updated model of the FixJ regulon.

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Pseudomonas azotifigens sp. nov., a novel nitrogen-fixing bacterium isolated from a compost pile

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY ◽

10.1099/ijs.0.63586-0 ◽

2005 ◽

Vol 55 (4) ◽

pp. 1539-1544 ◽

Cited By ~ 45

Author(s):

Kouta Hatayama ◽

Satomi Kawai ◽

Hirofumi Shoun ◽

Yasuichi Ueda ◽

Akira Nakamura

Keyword(s):

Nitrogen Fixation ◽

Nitrogenase Activity ◽

Sequence Similarity ◽

Phylogenetic Analyses ◽

Pseudomonas Stutzeri ◽

Sensu Stricto ◽

Rrna Gene ◽

Nitrogen Fixing ◽

Low Oxygen ◽

Close Relationship

A nitrogen-fixing bacterium, designated strain 6H33bT, was isolated from a compost pile in Japan. The nitrogenase activity of this strain was detected based on its acetylene-reducing activity under low oxygen concentrations (2–4 %). An analysis of the genes responsible for nitrogen fixation in this strain, nifH and nifD, indicated a close relationship to those of Pseudomonas stutzeri A15 (A1501). Sequence similarity searches based on the 16S rRNA gene sequences showed that strain 6H33bT belongs within the genus Pseudomonas sensu stricto; closest similarity was with Pseudomonas indica (97·3 %). A comparison of several taxonomic characteristics of 6H33bT with those of P. indica and some type strains of the genus Pseudomonas sensu stricto indicated that 6H33bT could be distinguished from P. indica based on the presence of nitrogen fixation ability, the absence of nitrate reduction and denitrification abilities and the utilization of some sugars and organic acids. Phylogenetic analyses and the results of DNA–DNA hybridization experiments also indicated that strain 6H33bT represents a species distinct from P. indica. From these results, it is proposed that strain 6H33bT (=ATCC BAA-1049T=JCM 12708T) is classified as the type strain of a novel species of the genus Pseudomonas sensu stricto under the name Pseudomonas azotifigens sp. nov.

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The Production of hydrogen Sulphide and the Effects of Nitric Oxide (NO) and Low Oxygen Conditions in Intrauterine Tissues in Rats

Bulletin of Egyptian Society for Physiological Sciences ◽

10.21608/besps.2009.36719 ◽

2009 ◽

Vol 29 (2) ◽

pp. 195-206

Author(s):

Saad El-Sekelly ◽

Mohamed Mahmoud ◽

Morsy Matar

Keyword(s):

Nitric Oxide ◽

Hydrogen Sulphide ◽

Low Oxygen ◽

Production Of Hydrogen ◽

Oxygen Conditions

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Identification and Functional Analysis of ThADH1 and ThADH4 Genes Involved in Tolerance to Waterlogging Stress in Taxodium hybrid ‘Zhongshanshan 406’

Genes ◽

10.3390/genes12020225 ◽

2021 ◽

Vol 12 (2) ◽

pp. 225

Author(s):

Lei Xuan ◽

Jianfeng Hua ◽

Fan Zhang ◽

Zhiquan Wang ◽

Xiaoxiao Pei ◽

...

Keyword(s):

Ethanol Metabolism ◽

Flooding Tolerance ◽

Transcriptome Data ◽

Low Oxygen ◽

Anaerobic Conditions ◽

Waterlogging Tolerance ◽

Waterlogging Stress ◽

Adh Genes ◽

Oxygen Conditions ◽

Stems And Leaves

The Taxodium hybrid ‘Zhongshanshan 406’ (T. hybrid ‘Zhongshanshan 406’) [Taxodium mucronatum Tenore × Taxodium distichum (L.). Rich] has an outstanding advantage in flooding tolerance and thus has been widely used in wetland afforestation in China. Alcohol dehydrogenase genes (ADHs) played key roles in ethanol metabolism to maintain energy supply for plants in low-oxygen conditions. Two ADH genes were isolated and characterized—ThADH1 and ThADH4 (GenBank ID: AWL83216 and AWL83217—basing on the transcriptome data of T. hybrid ‘Zhongshanshan 406’ grown under waterlogging stress. Then the functions of these two genes were investigated through transient expression and overexpression. The results showed that the ThADH1 and ThADH4 proteins both fall under ADH III subfamily. ThADH1 was localized in the cytoplasm and nucleus, whereas ThADH4 was only localized in the cytoplasm. The expression of the two genes was stimulated by waterlogging and the expression level in roots was significantly higher than those in stems and leaves. The respective overexpression of ThADH1 and ThADH4 in Populus caused the opposite phenotype, while waterlogging tolerance of the two transgenic Populus significantly improved. Collectively, these results indicated that genes ThADH1 and ThADH4 were involved in the tolerance and adaptation to anaerobic conditions in T. hybrid ‘Zhongshanshan 406’.

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