Hydrogenases, Nitrogenases, Anoxia, and H2 Production in Water-Oxidizing Phototrophs

Peters, John W.; Boyd, Eric S.; D’Adamo, Sarah; Mulder, David W.; Therien, Jesse; Posewitz, Matthew C.

doi:10.1007/978-94-007-5479-9_3

Cited by 9 publications

(6 citation statements)

References 384 publications

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“…Net H 2 production (biological controls minus killed controls) was measured in microcosms containing sediments from RSE1 and RSE5. Hydrogen production measured at RSE5 is potentially due to fermentation during periods of anoxia, possibly mediated by [FeFe]‐hydrogenase enzymes present in eukaryotic algal phototrophs (abundant at site RSE5 at 77% of eukaryotic reads) (Peters et al., ). However, H 2 cycling and the net H 2 production measured at RSE1 would not be influenced by phototrophs as this is above the temperature limit for phototrophic organisms.…”

Section: Discussionmentioning

confidence: 99%

Subsurface processes influence oxidant availability and chemoautotrophic hydrogen metabolism in Yellowstone hot springs

et al. 2018

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The geochemistry of hot springs and the availability of oxidants capable of supporting microbial metabolisms are influenced by subsurface processes including the separation of hydrothermal fluids into vapor and liquid phases. Here, we characterized the influence of geochemical variation and oxidant availability on the abundance, composition, and activity of hydrogen (H )-dependent chemoautotrophs along the outflow channels of two-paired hot springs in Yellowstone National Park. The hydrothermal fluid at Roadside East (RSE; 82.4°C, pH 3.0) is acidic due to vapor-phase input while the fluid at Roadside West (RSW; 68.1°C, pH 7.0) is circumneutral due to liquid-phase input. Most chemotrophic communities exhibited net rates of H oxidation, consistent with H support of primary productivity, with one chemotrophic community exhibiting a net rate of H production. Abundant H -oxidizing chemoautotrophs were supported by reduction in oxygen, elemental sulfur, sulfate, and nitrate in RSW and oxygen and ferric iron in RSE; O utilizing hydrogenotrophs increased in abundance down both outflow channels. Sequencing of 16S rRNA transcripts or genes from native sediments and dilution series incubations, respectively, suggests that members of the archaeal orders Sulfolobales, Desulfurococcales, and Thermoproteales are likely responsible for H oxidation in RSE, whereas members of the bacterial order Thermoflexales and the archaeal order Thermoproteales are likely responsible for H oxidation in RSW. These observations suggest that subsurface processes strongly influence spring chemistry and oxidant availability, which in turn select for unique assemblages of H oxidizing microorganisms. Therefore, these data point to the role of oxidant availability in shaping the ecology and evolution of hydrogenotrophic organisms.

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Section: Discussionmentioning

confidence: 99%

Subsurface processes influence oxidant availability and chemoautotrophic hydrogen metabolism in Yellowstone hot springs

et al. 2018

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“…Overall genes encoding hydrogenases, including both uptake (e.g., hya, hyb) and bidirectional hydrogenases (hox operon) comprised 5 % of the Energy Metabolism subsystem. Although in most mat ecosystems, the microbes are quite effective in sequestering the evolved H 2 (Peters et al 2013), the rates of H 2 production in these lithifying thrombolitic mats are unknown and needs to be examined. The novelty of many of the cyanobacteria within the thrombolitic mats and their various hydrogenases may help to improve the understanding of H 2 evolution in lithifying ecosystems, and this system has the potential to be exploited for renewable energy carrier production (Bothe et al 2010;Peters et al 2013).…”

Section: Cyanobacterial Molecular Pathways Dominate the Thrombolite Mmentioning

confidence: 99%

Metabolic potential of lithifying cyanobacteria-dominated thrombolitic mats

2013

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Thrombolites are unlaminated carbonate deposits formed by the metabolic activities of microbial mats and can serve as potential models for understanding the molecular mechanisms underlying the formation of lithifying communities. To assess the metabolic complexity of these ecosystems, high throughput DNA sequencing of a thrombolitic mat metagenome was coupled with phenotypic microarray analysis. Functional protein analysis of the thrombolite community metagenome delineated several of the major metabolic pathways that influence carbonate mineralization including cyanobacterial photosynthesis, sulfate reduction, sulfide oxidation, and aerobic heterotrophy. Spatial profiling of metabolite utilization within the thrombolite-forming microbial mats suggested that the top 5 mm contained a more metabolically diverse and active community than the deeper within the mat. This study provides evidence that despite the lack of mineral layering within the clotted thrombolite structure there is a vertical gradient of metabolic activity within the thrombolitic mat community. This metagenomic profiling also serves as a foundation for examining the active role individual functional groups of microbes play in coordinating metabolisms that lead to mineralization.

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“…Under these conditions, glyolysis produces pyruvate , ATP and NADH . The ever expanding number of available genome sequences will greatly extend our understanding of the genetic and putative functional diversity of [FeFe]-hydrogenase-encoding (HYDA ) and related fermentation genes in algal metabolism [73]. In C. reinhardtii, the primary fermentation products are formate, acetate, ethanol , H 2 and CO 2 , under most laboratory conditions.…”

Section: Fermentative H 2 Production In Algaementioning

confidence: 99%