Carbon isotope effects associated with autotrophic acetogenesis

Gelwicks, Jeffrey T.; Risatti, J. B.; Hayes, John M.

doi:10.1016/0146-6380(89)90009-0

Cited by 140 publications

(168 citation statements)

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“…As such, the carbon isotopic composition of acetate (δ 13 C-acetate) and ɛ ma can be estimated by mass balance using the data of δ 13 C-CH 4 and δ 13 C-CO 2 . Assuming the mass balance δ 13 C-acetate values to be representative of the δ 13 C value of the substrate, the average fractionation factor of CH 4 produced by acetoclastic methanogenesis (ɛ ma ) in this study's experiments at stationary phase is -12.05 ‰ ± 5.2 (Tables 4, 5, 6), which is in agreement with ε c values for acetate fermentation determined in other methanogenic microbial cultures (Gelwicks et al, 1994;Goevert and Conrad, 2009;Krzycki et al, 1987;Penning et al, 2006). However, if the ɛ ma values of samples that showed typical apparent isotopic fractionation of hydrogenotrophic methanogenesis are excluded (samples 5, 6 and 8 in Table 4 and sample 1 in Table 5), the average ɛ ma is -10.34 ‰ ± 2.1, which is quite similar to ɛ ma -10.2 ‰ that was observed for acetate metabolism by Methanosaeta concilii (Penning et al, 2006).…”

Section: Carbon Isotopessupporting

confidence: 76%

“…It has been noted that ε values tend to remain constant for each diagenetic environment, and as such, are indicative of a particular methanogenic pathway. For samples that produced α c = 1.02, the corresponding ε c values were in the range of -17 ‰ to -24 ‰, which are in agreement with ε c values for acetate fermentation determined in other methanogenic microbial cultures (Gelwicks et al, 1994;Goevert and Conrad, 2009;Krzycki et al, 1987;Penning et al, 2006).…”

Section: Fractionation Factor For Determining Methanogenesis Pathwaysupporting

confidence: 71%

“…There is a difference in the carbon isotope composition of gas produced from cultures of Methanosarcina and Methanosaeta, due to differences in their catabolic pathways (Gelwicks et al, 1994;Krzycki et al, 1987;Penning et al, 2006). Methanosaeta that are capable of growth in low acetate environments (minimum 7-70 µM) typically have a smaller carbon isotope fractionation factor when compared with Methanosarcina that have a minimum acetate threshold of 0.2-1.2 mM (Jetten et al, 1992).…”

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confidence: 99%

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Carbon and hydrogen isotope fractionation during methanogenesis: A laboratory study using coal and formation water

Susilawati

Golding

Baublys

et al. 2016

International Journal of Coal Geology

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Carbon and hydrogen isotope compositions of CH 4 generated via methanogenesis in cultures of South Sumatra Basin (SSB) coalbed methane (CBM) formation waters grown on coal, acetate and H 2 +CO 2 were investigated. CH 4 production and molecular analysis confirmed the presence of active microbial communities that are able to convert coal into CH 4 using both acetoclastic and hydrogenotrophic pathways. The representative bacterial sequences were dominated by Bacteroidetes, Firmicutes and Deltaproteobacteria, while Methanosaeta and Methanosarcina were the most prevalent archaeal methanogens present in the cultures.CH 4 produced in this study's culturing experiments has δ 13 C values in the range of -50 ‰ to -20 ‰, with most values falling outside the current understanding of the carbon isotopic boundaries for biogenic CH 4 (-110 ‰ to -30 ‰). However, the corresponding apparent carbon isotopic α factor (α c = 1.02±0.006), and isotopic effect (ε c = -20.1 ‰ ±15.3) showed that CH 4 in SSB cultures was predominantly produced by acetoclastic methanogenesis, which is consistent with the results of molecular DNA analysis. In addition, the calculated contribution of CO 2 reduction from the δ 13 C values of coaltreated cultures was overall < 50 %, further confirming the high contribution of the acetoclastic pathway to CH 4 production in the SSB cultures. The outcome of this experimental study also suggests that δ 2 H-CH 4 values may not provide a reliable basis for distinguishing methanogenic pathways, while apparent carbon isotopic fractionation factor (α c ) and isotope effect (ε c ) are considered more useful indicators of the methanogenic pathway.The high δ 13 C-CH 4 values (>-30 ‰) and the dominance of Methanosaeta over Methanosarcina indicate that methanogens within the SSB cultures were operating at low substrate concentrations. An unusually positive δ 13 C-CH 4 suggests a substrate depletion effect, which is thought to be related to a decrease in the relative abundance of key bacterial coal degraders with formation water inoculum storage time. Closer observation of δ 13 C-CH 4 values during the growth of cultures within a single experiment also showed a 13 C-enrichment trend over time. At log phase of growth, the CH 4 produced was 13 C-depleted when compared to the stationary phase that also indicates substrate depletion effects. Finally, the δ 13 C-CH 4 values encountered in this study (as high as -20 ‰) highlight the possible positive extension of δ 13 C-CH 4 values of acetoclastic methanogenesis from those currently reported in the literature for natural and experimental samples (as high as -30 ‰).Keywords: Biogenic gas, coal, culture experiment, isotopic composition INTRODUCTIONArchaeal methanogens are the only known microorganisms capable of forming CH 4 . These strictly anaerobic microbes are restricted to utilizing simple compounds that contain no more than two carbon atoms. As such, complex organic compounds in anoxic environments (e.g., marine sediments, rice paddies, subsurface shales and coalbeds) ...

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Section: Carbon Isotopessupporting

confidence: 76%

Section: Fractionation Factor For Determining Methanogenesis Pathwaysupporting

confidence: 71%

mentioning

confidence: 99%

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Carbon and hydrogen isotope fractionation during methanogenesis: A laboratory study using coal and formation water

Susilawati

Golding

Baublys

et al. 2016

International Journal of Coal Geology

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“…Assuming an average isotopic fractionation (i.e., e acetate/CO2 ) of -57% (Gelwicks et al, 1989;Heuer et al, 2010;Blaser et al, 2013), we would expect acetogenesis to produce acetate with d 13 C-values around -59% in the mofette soil, where d 13 C CO2 is on average -1.95±0.06% (Bräuer et al, 2004). However, the observed d 13 C of pore-water acetate ranged from -33.6% to -13.9%.…”

Section: Bacterial Groups Assimilating Volcanic Comentioning

confidence: 95%

“…We estimated the relative contribution of hydrogenotrophic and acetoclastic methanogenesis according to Conrad (2005) by using the d 13 C values of CH 4 , CO 2 and acetate, and isotopic fractionations of -71.8±8.8% (e CH4/CO2 ; for hydrogenotrophic methanogenesis in Methanoregulaceae dominated sediment (Liu et al, 2013) and -21% (e CH4/Acetate ; for acetoclastic methanogenesis by a pure culture of Methanosarcinaceae (Gelwicks et al, 1994). The contribution of hydrogenotrophic methanogenesis increased in the mofette soil from 5% in 5 cm to 44% in 10 cm depth.…”

Section: Bacterial Groups Assimilating Volcanic Comentioning

confidence: 99%

Carbon flow from volcanic CO2 into soil microbial communities of a wetland mofette

et al. 2014

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Effects of extremely high carbon dioxide (CO 2 ) concentrations on soil microbial communities and associated processes are largely unknown. We studied a wetland area affected by spots of subcrustal CO 2 degassing (mofettes) with focus on anaerobic autotrophic methanogenesis and acetogenesis because the pore gas phase was largely hypoxic. Compared with a reference soil, the mofette was more acidic (DpH B0.8), strongly enriched in organic carbon (up to 10 times), and exhibited lower prokaryotic diversity. It was dominated by methanogens and subdivision 1 Acidobacteria, which likely thrived under stable hypoxia and acidic pH. Anoxic incubations revealed enhanced formation of acetate and methane (CH 4 ) from hydrogen (H 2 ) and CO 2 consistent with elevated CH 4 and acetate levels in the mofette soil. 13 CO 2 mofette soil incubations showed high label incorporations with B512 ng 13 C g (dry weight (dw)) soil À 1 d À 1 into the bulk soil and up to 10.7 ng 13 C g (dw) soil À 1 d À 1 into almost all analyzed bacterial lipids. Incorporation of CO 2 -derived carbon into archaeal lipids was much lower and restricted to the first 10 cm of the soil. DNA-SIP analysis revealed that acidophilic methanogens affiliated with Methanoregulaceae and hitherto unknown acetogens appeared to be involved in the chemolithoautotrophic utilization of 13 CO 2 . Subdivision 1 Acidobacteriaceae assimilated 13 CO 2 likely via anaplerotic reactions because Acidobacteriaceae are not known to harbor enzymatic pathways for autotrophic CO 2 assimilation. We conclude that CO 2 -induced geochemical changes promoted anaerobic and acidophilic organisms and altered carbon turnover in affected soils.

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Geochemical and Geological Significance of Subsurface Microbiology

Onstott

2003

Encyclopedia of Environmental Microbiology

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Carbon isotope effects associated with autotrophic acetogenesis

Cited by 140 publications

References 24 publications

Carbon and hydrogen isotope fractionation during methanogenesis: A laboratory study using coal and formation water

Carbon and hydrogen isotope fractionation during methanogenesis: A laboratory study using coal and formation water

Carbon flow from volcanic CO2 into soil microbial communities of a wetland mofette

Geochemical and Geological Significance of Subsurface Microbiology

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