Hydrogenase and Energy Efficiency in Nitrogen Fixing Symbionts

Brewin, N. J.

doi:10.1007/978-3-7091-8739-5_6

Cited by 24 publications

(9 citation statements)

References 76 publications

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“…Nitrogen fixation is one of the main processes of biogenic H 2 production and is catalyzed by nitrogenase (Figure 1D). Approximately 30–50% of the entire reduction power consumed by nitrogenase is laterally tracked to H 2 evolution (Brewin, 1984; Evans et al, 1987). However, H 2 is not both a competitive inhibitor of N 2 fixation and also represents a net loss of energy unless the H 2 can be reprocessed by means of the uptake hydrogenase (Kosourov et al, 2014).…”

Section: Microbial H2-producing Processes and Their Impact On The Envmentioning

confidence: 99%

Function of Biohydrogen Metabolism and Related Microbial Communities in Environmental Bioremediation

Teng

Wang

et al. 2019

Front. Microbiol.

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Hydrogen (H 2 ) metabolism has attracted considerable interest because the activities of H 2 -producing and consuming microbes shape the global H 2 cycle and may have vital relationships with the global cycling of other elements. There are many pathways of microbial H 2 emission and consumption which may affect the structure and function of microbial communities. A wide range of microbial groups employ H 2 as an electron donor to catalyze the reduction of pollutants such as organohalides, azo compounds, and trace metals. Syntrophy coupled mutualistic interaction between H 2 -producing and H 2 -consuming microorganisms can transfer H 2 and be accompanied by the removal of toxic compounds. Moreover, hydrogenases have been gradually recognized to have a key role in the progress of pollutant degradation. This paper reviews recent advances in elucidating role of H 2 metabolism involved in syntrophy and hydrogenases in environmental bioremediation. Further investigations should focus on the application of bioenergy in bioremediation to make microbiological H 2 metabolism a promising remediation strategy.

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Section: Microbial H2-producing Processes and Their Impact On The Envmentioning

confidence: 99%

Function of Biohydrogen Metabolism and Related Microbial Communities in Environmental Bioremediation

Teng

Wang

et al. 2019

Front. Microbiol.

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“…The generation of hydrogen by legume nodules as a consequence of the N2 reduction catalyzed by nitrogenase is a potential source of inefficiency of the Rhizobium-legume symbiosis. In nodules produced by a limited number of Bradyrhizobium and Rhizobium strains, H2 is recycled by means of an H2 uptake system and oxidized to water (3,12,14). The utilization of the nitrogenase-generated H2 in these nodules has been shown to provide ATP for nitrogen fixation, to protect nitrogenase against 02, and to use up H2, preventing nitrogenase inhibition by H2 (3,12).…”

mentioning

confidence: 99%

“…In nodules produced by a limited number of Bradyrhizobium and Rhizobium strains, H2 is recycled by means of an H2 uptake system and oxidized to water (3,12,14). The utilization of the nitrogenase-generated H2 in these nodules has been shown to provide ATP for nitrogen fixation, to protect nitrogenase against 02, and to use up H2, preventing nitrogenase inhibition by H2 (3,12). Some of these putative advantages may be responsible for the beneficial effects of the H2-uptake system on whole-plant growth and nitrogen fixation that have been observed in soybeans nodulated by Hup+ (H2-uptake-hydrogenase-positive) strains of Bradyrhizobium japonicum (14,16).…”

mentioning

confidence: 99%

Conserved Plasmid Hydrogen-Uptake ( hup )-Specific Sequences within Hup ⁺ Rhizobium leguminosarum Strains

Leyva

Palacios

Ruiz-Argüeso

1987

Appl Environ Microbiol

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Thirteen Rhizobium leguminosarum strains previously reported as H 2 -uptake hydrogenase positive (Hup + ) or negative (Hup − ) were analyzed for the presence and conservation of DNA sequences homologous to cloned Bradyrhizobium japonicum hup -specific DNA from cosmid pHU1 (M. A. Cantrell, R. A. Haugland, and H. J. Evans, Proc. Natl. Acad. Sci. USA 80:181-185, 1983). The Hup phenotype of these strains was reexamined by determining hydrogenase activity induced in bacteroids from pea nodules. Five strains, including H 2 oxidation-ATP synthesis-coupled and -uncoupled strains, induced significant rates of H 2 -uptake hydrogenase activity and contained DNA sequences homologous to three probe DNA fragments (5.9-kilobase [kb] Hin dIII, 2.9-kb Eco RI, and 5.0-kb Eco RI) from pHU1. The pattern of genomic DNA Hin dIII and Eco RI fragments with significant homology to each of the three probes was identical in all five strains regardless of the H 2 -dependent ATP generation trait. The restriction fragments containing the homology totalled about 22 kb of DNA common to the five strains. In all instances the putative hup sequences were located on a plasmid that also contained nif genes. The molecular sizes of the identified hup-sym plasmids ranged between 184 and 212 megadaltons. No common DNA sequences homologous to B. japonicum hup DNA were found in genomic DNA from any of the eight remaining strains showing no significant hydrogenase activity in pea bacteroids. These results suggest that the identified DNA region contains genes essential for hydrogenase activity in R. leguminosarum and that its organization is highly conserved within Hup + strains in this symbiotic species.

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“…Hydrogen could be an alternative energy source, implicated by the presence of hydrogenase genes. Such a process may also contribute to the removal of H 2 and oxygen from the active site of the nitrogenase (Brewin, 1984). The presence of dsrAB genes suggests that Chlorobi can use sulfide as electron donor.…”

Section: Chlorobimentioning

confidence: 99%

Diazotroph Genomes and Their Seasonal Dynamics in a Stratified Humic Bog Lake

et al. 2020

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Aquatic N-fixation is generally associated with the growth and mass development of Cyanobacteria in nitrogen-deprived photic zones. However, sequenced genomes and environmental surveys suggest active aquatic N-fixation also by many noncyanobacterial groups. Here, we revealed the seasonal variation and genomic diversity of potential N-fixers in a humic bog lake using metagenomic data and nif gene clusters analysis. Groups with diazotrophic operons were functionally divergent and included Cholorobi, Geobacter, Desulfobacterales, Methylococcales, and Acidobacteria. In addition to nifH (a gene that encodes the dinitrogenase reductase component of the molybdenum nitrogenase), we also identified sequences corresponding to vanadium and iron-only nitrogenase genes. Within the Chlorobi population, the nitrogenase (nifH) cluster was included in a well-structured retrotransposon. Furthermore, the presence of light-harvesting photosynthesis genes implies that anoxygenic photosynthesis may fuel nitrogen fixation under the prevailing low-irradiance conditions. The presence of rnf genes (related to the expression of H + /Na +-translocating ferredoxin: NAD+ oxidoreductase) in Methylococcales and Desulfobacterales suggests that other energygenerating processes may drive the costly N-fixation in the absence of photosynthesis. The highly reducing environment of the anoxic bottom layer of Trout Bog Lake may thus also provide a suitable niche for active N-fixers and primary producers. While future studies on the activity of these potential N-fixers are needed to clarify their role in freshwater nitrogen cycling, the metagenomic data presented here enabled an initial characterization of previously overlooked diazotrophs in freshwater biomes.

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Hydrogenase and Energy Efficiency in Nitrogen Fixing Symbionts

Cited by 24 publications

References 76 publications

Function of Biohydrogen Metabolism and Related Microbial Communities in Environmental Bioremediation

Function of Biohydrogen Metabolism and Related Microbial Communities in Environmental Bioremediation

Conserved Plasmid Hydrogen-Uptake ( hup )-Specific Sequences within Hup ⁺ Rhizobium leguminosarum Strains

Diazotroph Genomes and Their Seasonal Dynamics in a Stratified Humic Bog Lake

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Hydrogenase and Energy Efficiency in Nitrogen Fixing Symbionts

Cited by 24 publications

References 76 publications

Function of Biohydrogen Metabolism and Related Microbial Communities in Environmental Bioremediation

Function of Biohydrogen Metabolism and Related Microbial Communities in Environmental Bioremediation

Conserved Plasmid Hydrogen-Uptake ( hup )-Specific Sequences within Hup + Rhizobium leguminosarum Strains

Diazotroph Genomes and Their Seasonal Dynamics in a Stratified Humic Bog Lake

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Conserved Plasmid Hydrogen-Uptake ( hup )-Specific Sequences within Hup ⁺ Rhizobium leguminosarum Strains