H2-Metabolizing Prokaryotes

Schwartz, Edward L.; Fritsch, Johannes; Friedrich, Bärbel

doi:10.1007/978-3-642-30141-4_65

Cited by 83 publications

(144 citation statements)

References 920 publications

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“…Microorganisms are able to harness these properties by consuming and producing H 2 using specialised metalloenzymes called hydrogenases (Schwartz et al, 2013). There are three phylogenetically unrelated classes of hydrogenase distinguishable based on the metal content of their H 2 -binding sites: the [NiFe]-, [FeFe]-and [Fe]-hydrogenases (Volbeda et al, 1995;Peters et al, 1998;Shima et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…H 2 oxidation by such enzymes yields low-potential electrons that are transduced through respiratory chains or used to fix inorganic carbon. In contrast, H 2 evolution efficiently dissipates excess reductant as a diffusible gas during microbial fermentation and photobiological processes (Schwartz et al, 2013). Certain hydrogenases are also part of low-potential ion-translocating complexes that use protons as terminal electron acceptors (Buckel and Thauer, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Genomic and metagenomic surveys of hydrogenase distribution indicate H2 is a widely utilised energy source for microbial growth and survival

et al. 2015

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Recent physiological and ecological studies have challenged the long-held belief that microbial metabolism of molecular hydrogen (H 2 ) is a niche process. To gain a broader insight into the importance of microbial H 2 metabolism, we comprehensively surveyed the genomic and metagenomic distribution of hydrogenases, the reversible enzymes that catalyse the oxidation and evolution of H 2 . The protein sequences of 3286 non-redundant putative hydrogenases were curated from publicly available databases. These metalloenzymes were classified into multiple groups based on (1) amino acid sequence phylogeny, (2) metal-binding motifs, (3) predicted genetic organisation and (4) reported biochemical characteristics. Four groups (22 subgroups) of [NiFe]-hydrogenase, three groups (6 subtypes) of [FeFe]-hydrogenases and a small group of [Fe]-hydrogenases were identified. We predict that this hydrogenase diversity supports H 2 -based respiration, fermentation and carbon fixation processes in both oxic and anoxic environments, in addition to various H 2 -sensing, electron-bifurcation and energy-conversion mechanisms. Hydrogenase-encoding genes were identified in 51 bacterial and archaeal phyla, suggesting strong pressure for both vertical and lateral acquisition. Furthermore, hydrogenase genes could be recovered from diverse terrestrial, aquatic and host-associated metagenomes in varying proportions, indicating a broad ecological distribution and utilisation. Oxygen content (pO 2 ) appears to be a central factor driving the phylum-and ecosystem-level distribution of these genes. In addition to compounding evidence that H 2 was the first electron donor for life, our analysis suggests that the great diversification of hydrogenases has enabled H 2 metabolism to sustain the growth or survival of microorganisms in a wide range of ecosystems to the present day. This work also provides a comprehensive expanded system for classifying hydrogenases and identifies new prospects for investigating H 2 metabolism.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Genomic and metagenomic surveys of hydrogenase distribution indicate H2 is a widely utilised energy source for microbial growth and survival

et al. 2015

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“…7 In such environments, H 2 is produced predominantly by fermentative bacteria (hydrogenogens) and is thought to be reoxidised primarily by anaerobic respiratory microorganisms (hydrogenotrophs). H 2 consumption is thermodynamically essential in any environment to maintain fermentative processes, and is accomplished in the sediment through interspecies hydrogen transfer or competitive hydrogenotrophy.…”

Section: Introductionmentioning

confidence: 99%

“…H 2 consumption is thermodynamically essential in any environment to maintain fermentative processes, and is accomplished in the sediment through interspecies hydrogen transfer or competitive hydrogenotrophy. 7 Interspecies hydrogen transfer is the syntrophic evolution and consumption of hydrogen between organisms in such close proximity that hydrogen never joins the dissolved hydrogen pool. 8,9 In contrast, competitive hydrogenotrophy pairs the oxidation of organic substrates by hydrogenogens with the reduction of terminal electron acceptors by hydrogenotrophs, which results in a well described ecological framework determined by H 2 concentration and substrate availability.…”

Section: Introductionmentioning

confidence: 99%

“…These ubiquitous enzymes are found in Archaea, Bacteria, and some Eukarya, and include both anaerobically-and aerobically-adapted variants. 7,19 In anoxic environments such as the human colon, hydrogenases can potentially conserve energy through 3 major processes: 1) hydrogenotrophic respiration by coupling oxidation of the high-energy fuel H 2 to the reduction of exogenous oxidants such as sulfate; 20,21 2) hydrogenogenic fermentation by coupling oxidation of ferredoxin or formate to the production of the dissipatable H 2 ; 22,23 or 3) hydrogenogenic respiration by coupling ferredoxin oxidation to proton reduction in cationtranslocating complexes. 24,25 More recently, a fourth mechanism of H 2 -dependent energy conservation has been described in acetogens and methanogens: flavinbased electron bifurcation.…”

Section: Introductionmentioning

confidence: 99%

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H₂metabolism is widespread and diverse among human colonic microbes

et al. 2016

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Microbial molecular hydrogen (H 2 ) cycling is central to metabolic homeostasis and microbial composition in the human gastrointestinal tract. Molecular H 2 is produced as an endproduct of carbohydrate fermentation and is reoxidised primarily by sulfate-reduction, acetogenesis, and methanogenesis. However, the enzymatic basis for these processes is incompletely understood and the hydrogenases responsible have not been investigated. In this work, we surveyed the genomic and metagenomic distribution of hydrogenase-encoding genes in the human colon to infer dominant mechanisms of H 2 cycling. The data demonstrate that 70% of gastrointestinal microbial species listed in the Human Microbiome Project encode the genetic capacity to metabolise H 2 . A wide variety of anaerobicallyadapted hydrogenases were present, with [FeFe]-hydrogenases predominant. We subsequently analyzed the hydrogenase gene content of stools from 20 healthy human subjects. The hydrogenase gene content of all samples was overwhelmingly dominated by fermentative and electron-bifurcating [FeFe]-hydrogenases emerging from the Bacteroidetes and Firmicutes. This study supports that H 2 metabolism in the human gut is driven by fermentative H 2 production and interspecies H 2 transfer. However, it suggests that electron-bifurcation rather than respiration is the dominant mechanism of H 2 reoxidation in the human colon, generating reduced ferredoxin to sustain carbon-fixation (e.g. acetogenesis) and respiration (via the Rnf complex). This work provides the first comprehensive bioinformatic insight into the mechanisms of H 2 metabolism in the human colon.

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Biohydrogen for a New Generation of H₂/O₂ Biofuel Cells: A Sustainable Energy Perspective

et al. 2014

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Among sustainable alternatives to fossil fuel, proton exchange membrane fuel cells are promising devices that deliver electricity from hydrogen and oxygen, producing only water. The transformation of the fuel and oxidant however relies on rare‐metal catalysts. H2/O2 enzymatic biofuel cells thus emerge as sustainable biotechnological devices in which chemical catalysts are replaced by hydrogenases at the anode and multicopper oxidases at the cathode. This review discusses the recent breakthroughs and the limitations in all the components of H2/O2 biofuel cells: 1) Catalytic mechanisms involved in multicopper oxidases and hydrogenases, in addition to the new potential of enzymes from the biodiversity pool, which exhibit outstanding properties. 2) The molecular basis for oriented enzyme immobilization on the electrochemical interfaces as a prerequisite for a fast direct electron‐transfer rate. 3) The requirement for 3D networks to enhance current densities. 4) The production of H2 from biomass. 5) The history of H2/O2 biofuel cells and recent devices, which also highlights the remaining issues that will allow the use of such devices in low‐power applications.

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H2-Metabolizing Prokaryotes

Cited by 83 publications

References 920 publications

Genomic and metagenomic surveys of hydrogenase distribution indicate H2 is a widely utilised energy source for microbial growth and survival

Genomic and metagenomic surveys of hydrogenase distribution indicate H2 is a widely utilised energy source for microbial growth and survival

H₂metabolism is widespread and diverse among human colonic microbes

Biohydrogen for a New Generation of H₂/O₂ Biofuel Cells: A Sustainable Energy Perspective

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H2-Metabolizing Prokaryotes

Cited by 83 publications

References 920 publications

Genomic and metagenomic surveys of hydrogenase distribution indicate H2 is a widely utilised energy source for microbial growth and survival

Genomic and metagenomic surveys of hydrogenase distribution indicate H2 is a widely utilised energy source for microbial growth and survival

H2metabolism is widespread and diverse among human colonic microbes

Biohydrogen for a New Generation of H2/O2 Biofuel Cells: A Sustainable Energy Perspective

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Product

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H₂metabolism is widespread and diverse among human colonic microbes

Biohydrogen for a New Generation of H₂/O₂ Biofuel Cells: A Sustainable Energy Perspective