Thermodynamic and kinetic analysis of the H2 threshold for Methanobacterium bryantii M.o.H

Karadagli, Fatih; Rittmann, Bruce E.

doi:10.1007/s10532-006-9073-7

Cited by 33 publications

(26 citation statements)

References 51 publications

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“…H 2 concentration in these samples was ≤1 nM, but may have allowed minor CH 4 formation (Fig. 2c, 4) (Karadagli and Rittmann, 2007). This agrees with observations in a rice field and in rice soil microcosms, in which only minor residual CH 4 production from H 2 /CO 2 occurred during the Fe-reducing phase (Frenzel et al, 1999;Krüger et al, 2002;Lueders and Friedrich, 2002 Tree-Puzzle tree of mcrA-sequences.…”

Section: Discussionsupporting

confidence: 88%

Wetland restoration and methanogenesis: the activity of microbial populations and competition for substrates at different temperatures

et al. 2009

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Abstract. Ljubljana marsh in Slovenia is a 16 000 ha area of partly drained fen, intended to be flooded to restore its ecological functions. The resultant water-logging may create anoxic conditions, eventually stimulating production and emission of methane, the most important greenhouse gas next to carbon dioxide. We examined the upper layer (∼30 cm) of Ljubljana marsh soil for microbial processes that would predominate in water-saturated conditions, focusing on the potential for iron reduction, carbon mineralization (CO 2 and CH 4 production), and methane emission. Methane emission from water-saturated microcosms was near minimum detectable levels even after extended periods of flooding (>5 months). Methane production in anoxic soil slurries started only after a lag period of 84 d at 15 • C and a minimum of 7 d at 37 • C, the optimum temperature for methanogenesis. This lag was inversely related to iron reduction, which suggested that iron reduction out-competed methanogenesis for electron donors, such as H 2 and acetate. Methane production was observed only in samples incubated at 14-38 • C. At the beginning of methanogenesis, acetoclastic methanogenesis dominated. In accordance with the preferred substrate, most (91%) mcrA (encoding the methyl coenzyme-M reductase, a key gene in methanogenesis) clone sequences could be affiliated to the acetoclastic genus Methanosarcina. No methanogens were detected in the original soil. However, a diverse community of iron-reducing Geobacteraceae was found. Our results suggest that methane emission can remain transient and low if water-table fluctuations allow reoxidation of ferrous iron, sustaining iron reduction as the most important process in terminal carbon mineralization.

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Section: Discussionsupporting

confidence: 88%

Wetland restoration and methanogenesis: the activity of microbial populations and competition for substrates at different temperatures

et al. 2009

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“…These high concentrations could be a result of biological H 2 production by anaerobic CO oxidizers and are consistent with the elevated CO concentrations at the collection site. The hydrogen concentrations in the worms' habitat are much higher than those needed by common hydrogen-oxidizing microorganisms for growth (23), indicating that the δ-symbionts could easily use the hydrogen present in the Elba sediment as an energy source. The use of hydrogen as an energy source by chemoautotrophic sulfur-oxidizing symbionts was shown recently for deep-sea Bathymodiolus mussels from hydrothermal vents (24).…”

Section: Resultsmentioning

confidence: 99%

Metaproteomics of a gutless marine worm and its symbiotic microbial community reveal unusual pathways for carbon and energy use

Kleiner

Wentrup

Lott

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

187

251

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Low nutrient and energy availability has led to the evolution of numerous strategies for overcoming these limitations, of which symbiotic associations represent a key mechanism. Particularly striking are the associations between chemosynthetic bacteria and marine animals that thrive in nutrient-poor environments such as the deep sea because the symbionts allow their hosts to grow on inorganic energy and carbon sources such as sulfide and CO 2 . Remarkably little is known about the physiological strategies that enable chemosynthetic symbioses to colonize oligotrophic environments. In this study, we used metaproteomics and metabolomics to investigate the intricate network of metabolic interactions in the chemosynthetic association between Olavius algarvensis, a gutless marine worm, and its bacterial symbionts. We propose previously undescribed pathways for coping with energy and nutrient limitation, some of which may be widespread in both freeliving and symbiotic bacteria. These pathways include (i) a pathway for symbiont assimilation of the host waste products acetate, propionate, succinate and malate; (ii) the potential use of carbon monoxide as an energy source, a substrate previously not known to play a role in marine invertebrate symbioses; (iii) the potential use of hydrogen as an energy source; (iv) the strong expression of high-affinity uptake transporters; and (v) as yet undescribed energy-efficient steps in CO 2 fixation and sulfate reduction. The high expression of proteins involved in pathways for energy and carbon uptake and conservation in the O. algarvensis symbiosis indicates that the oligotrophic nature of its environment exerted a strong selective pressure in shaping these associations.3-hydroxypropionate bi-cycle | Calvin cycle | proton-translocating pyrophosphatase | pyrophosphate dependent phosphofructokinase | metagenomics G rowth in nutrient-limited environments presents numerous challenges to organisms. Symbiotic and syntrophic relationships have evolved as particularly successful strategies for coping with these challenges. Such nutritional symbioses are widespread in nature and, for example, have enabled plants to colonize nitrogen-poor soils and animals to thrive on food sources that lack essential amino acids and vitamins (1). Chemosynthetic symbioses, discovered only 35 years ago at hydrothermal vents in the deep sea, revolutionized our understanding of nutritional associations, because these symbioses enable animals to live on inorganic energy and carbon sources such as sulfide and CO 2 (2, 3). The chemosynthetic symbionts use the energy obtained from oxidizing reduced inorganic compounds such as sulfide to fix CO 2 , ultimately providing their hosts with organic carbon compounds. Chemosynthetic symbioses thus are able to thrive in habitats where organic carbon sources are rare, such as the deep sea, and the symbionts often are so efficient at providing nutrition that many hosts have reduced their digestive systems (4).The marine oligochaete Olavius algarvensis is a particularly extre...

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“…In the unamended Clueless sample, H 2 ( o 5 nM) is close to or below the H 2 threshold values of most microorganisms (e.g. Karadagli & Rittmann, 2007) and is therefore unlikely to be the residual inorganic electron donor powering autotrophy. In these effluents, sulfide accounts for 21 AE 17 mM and can therefore be considered a putative inorganic electron source for energy-yielding oxidation processes in the unamended Clueless incubations.…”

Section: Microbial Co 2 Fixation Rates Based On Incubation Experimentsmentioning

confidence: 86%

Geochemical constraints on the diversity and activity of H2-oxidizing microorganisms in diffuse hydrothermal fluids from a basalt- and an ultramafic-hosted vent

Perner¹,

Petersen²,

Zielinski³

et al. 2010

FEMS Microbiology Ecology

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Mixing processes of reduced hydrothermal fluids with oxygenated seawater and fluid-rock reactions contribute to the chemical signatures of diffuse venting and likely determine the geochemical constraints on microbial life. We examined the influence of fluid chemistry on microbial diversity and activity by sampling diffuse fluids emanating through mussel beds at two contrasting hydrothermal vents. The H 2 concentration was very low at the basalt-hosted Clueless site, and mixing models suggest O 2 availability throughout much of the habitat. In contrast, effluents from the ultramafic-hosted Quest site were considerably enriched in H 2 , while O 2 is likely limited to the mussel layer. Only two different hydrogenase genes were identified in clone libraries from the H 2 -poor Clueless fluids, but these fluids exhibited the highest H 2 uptake rates in H 2 -spiked incubations (oxic conditions, at 18 1C). In contrast, a phylogenetically diverse H 2 -oxidizing potential was associated with distinct thermal conditions in the H 2 -rich Quest fluids, but under oxic conditions, H 2 uptake rates were extremely low. Significant stimulation of CO 2 fixation rates by H 2 addition was solely illustrated in Quest incubations (P-value o 0.02), but only in conjunction with anoxic conditions (at 18 1C). We conclude that the factors contributing toward differences in the diversity and activity of H 2 oxidizers at these sites include H 2 and O 2 availability.

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Thermodynamic and kinetic analysis of the H2 threshold for Methanobacterium bryantii M.o.H

Cited by 33 publications

References 51 publications

Wetland restoration and methanogenesis: the activity of microbial populations and competition for substrates at different temperatures

Wetland restoration and methanogenesis: the activity of microbial populations and competition for substrates at different temperatures

Metaproteomics of a gutless marine worm and its symbiotic microbial community reveal unusual pathways for carbon and energy use

Geochemical constraints on the diversity and activity of H2-oxidizing microorganisms in diffuse hydrothermal fluids from a basalt- and an ultramafic-hosted vent

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