Acetogenic Prokaryotes

Drake, Harold L.; Küsel, Kirsten; Matthies, Carola

doi:10.1007/0-387-30742-7_13

Cited by 187 publications

(226 citation statements)

References 453 publications

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“…Consistent with our quantification of cbbL/cbbM marker genes, Beulig et al (2016) detected high frequencies of transcripts encoding key enzymes for the CBB as well as the reductive acetyl-CoA (coenzyme A) cycle. The acetyl-CoA Cycle is used by acetogens, methanogens, and sulfate reducers for catabolism and anabolism (Drake et al, 2006). According to Beulig et al (2016), transcripts of key enzymes for the acetyl-CoA pathway in the mofette soil are also related to these groups.…”

Section: Quantification Of Microbial Carbon C Derived From Co 2 Fixationmentioning

confidence: 99%

Autotrophic fixation of geogenic CO<sub>2</sub> by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

et al. 2015

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Abstract.To quantify the contribution of autotrophic microorganisms to organic matter (OM) formation in soils, we investigated natural CO 2 vents (mofettes) situated in a wetland in northwest Bohemia (Czech Republic). Mofette soils had higher soil organic matter (SOM) concentrations than reference soils due to restricted decomposition under high CO 2 levels. We used radiocarbon ( 14 C) and stable carbon (δ 13 C) isotope ratios to characterize SOM and its sources in two mofettes and compared it with respective reference soils, which were not influenced by geogenic CO 2 .The geogenic CO 2 emitted at these sites is free of radiocarbon and enriched in 13 C compared to atmospheric CO 2 . Together, these isotopic signals allow us to distinguish C fixed by plants from C fixed by autotrophic microorganisms using their differences in 13 C discrimination. We can then estimate that up to 27 % of soil organic matter in the 0-10 cm layer of these soils was derived from microbially assimilated CO 2 .Isotope values of bulk SOM were shifted towards more positive δ 13 C and more negative 14 C values in mofettes compared to reference soils, suggesting that geogenic CO 2 emitted from the soil atmosphere is incorporated into SOM. To distinguish whether geogenic CO 2 was fixed by plants or by CO 2 assimilating microorganisms, we first used the proportional differences in radiocarbon and δ 13 C values to indicate the magnitude of discrimination of the stable isotopes in living plants. Deviation from this relationship was taken to indicate the presence of microbial CO 2 fixation, as microbial discrimination should differ from that of plants. 13 CO 2 -labelling experiments confirmed high activity of CO 2 assimilating microbes in the top 10 cm, where δ 13 C values of SOM were shifted up to 2 ‰ towards more negative values. Uptake rates of microbial CO 2 fixation ranged up to 1.59 ± 0.16 µg g −1 dw d −1 . We inferred that the negative δ 13 C shift was caused by the activity of autotrophic microorganisms using the Calvin-Benson-Bassham (CBB) cycle, as indicated from quantification of cbbL/cbbM marker genes encoding for RubisCO by quantitative polymerase chain reaction (qPCR) and by acetogenic and methanogenic microorganisms, shown present in the mofettes by previous studies. Combined 14 C and δ 13 C isotope mass balances indicated that microbially derived carbon accounted for 8-27 % of bulk SOM in this soil layer.The findings imply that autotrophic microorganisms can recycle significant amounts of carbon in wetland soils and might contribute to observed radiocarbon reservoir effects influencing 14 C signatures in peat deposits.

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Section: Quantification Of Microbial Carbon C Derived From Co 2 Fixationmentioning

confidence: 99%

Autotrophic fixation of geogenic CO<sub>2</sub> by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

et al. 2015

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“…2). Obligately anaerobic, CO 2 -reducing acetogens and methanogens use the Wood-Ljungdahl (acetyl-CoA) pathway not only as a terminal electron accepting, energy-conserving process, but also as a mechanism for cell carbon synthesis from CO 2 (Drake et al, 2006). The methane and acetate produced then supports the growth of acetoclastic methanogens, sulfate-(SRB), and iron-reducing bacteria (FeRB).…”

Section: Impact Of Physical Complexity On Cz Microbiologymentioning

confidence: 99%

Where microorganisms meet rocks in the Earth's Critical Zone

Akob

Küsel

2011

Biogeosciences

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Abstract. The Critical Zone (CZ) is the Earth's outer shell where all the fundamental physical, chemical, and biological processes critical for sustaining life occur and interact. As microbes in the CZ drive many of these biogeochemical cycles, understanding their impact on life-sustaining processes starts with an understanding of their biodiversity. In this review, we summarize the factors controlling where terrestrial CZ microbes (prokaryotes and micro-eukaryotes) live and what is known about their diversity and function. Microbes are found throughout the CZ, down to 5 km below the surface, but their functional roles change with depth due to habitat complexity, e.g. variability in pore spaces, water, oxygen, and nutrients. Abundances of prokaryotes and micro-eukaryotes decrease from 10 10 or 10 7 cells g soil −1 or rock −1 , or ml water −1 by up to eight orders of magnitude with depth. Although symbiotic mycorrhizal fungi and freeliving decomposers have been studied extensively in soil habitats, where they occur up to 10 3 cells g soil −1 , little is known regarding their identity or impact on weathering in the deep subsurface. The relatively low abundance of microeukaryotes in the deep subsurface suggests that they are limited in space, nutrients, are unable to cope with oxygen limitations, or some combination thereof. Since deep regions of the CZ have limited access to recent photosynthesis-derived carbon, microbes there depend on deposited organic material or a chemolithoautotrophic metabolism that allows for a complete food chain, independent from the surface, although limited energy flux means cell growth may take tens to thousands of years. Microbes are found in all regions of the CZ and can mediate important biogeochemical processes, but more work is needed to understand how microbial populations influence the links between different regions of the CZ and weathering processes. With the recent development of "omics" technologies, microbial ecologists have new methods that can be used to link the composition and function of in situ microbial communities. In particular, these methods can be used to search for new metabolic pathways that are Correspondence to: K. Küsel (kirsten.kuesel@uni-jena.de) relevant to biogeochemical nutrient cycling and determine how the activity of microorganisms can affect transport of carbon, particulates, and reactive gases between and within CZ regions.

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“…Reductive acetogens are a group of bacteria that can produce acetate from hydrogen and carbon dioxides (4H 2 +2CO 2 →CH 3 COOH+2H 2 O) using the acetyl-CoA pathway (Drake et al, 2006). This suggests that acetogens may serve as hydrogen sinks in experiments, which seek to lower methane emissions (van Nevel and Demeyer, 1995;Morvan et al, 1996;Joblin, 1999) in cattle.…”

Section: Introductionmentioning

confidence: 99%

Rumen fermentation and acetogen population changes in response to an exogenous acetogen TWA4 strain and Saccharomyces cerevisiae fermentation product

Yang

Guan

Liu

et al. 2015

J. Zhejiang Univ. Sci. B

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Abstract:The presence of yeast cells could stimulate hydrogen utilization of acetogens and enhance acetogenesis. To understand the roles of acetogens in rumen fermentation, an in vitro rumen fermentation experiment was conducted with addition of acetogen strain (TWA4) and/or Saccharomyces cerevisiae fermentation product (XP). A 2×2 factorial design with two levels of TWA4 (0 or 2×10 7 cells/ml) and XP (0 or 2 g/L) was performed. Volatile fatty acids (VFAs) were increased (P<0.05) in XP and TWA4XP, while methane was increased only in TWA4XP (P<0.05). The increase rate of microorganisms with formyltetrahydrofolate synthetase, especially acetogens, was higher than that of methanogens under all treatments. Lachnospiraceae was predominant in all acetogen communities, but without close acetyl-CoA synthase (ACS) amino acid sequences from cultured isolates. Low-Acetitomaculum ruminis-like ACS was predominant in all acetogen communities, while four unique phylotypes in XP treatment were all amino acid identified low-Eubacterium limosum-like acetogens. It differs to XP treatment that more low-A. ruminis-like and less low-E. limosum-like sequences were identified in TWA4 and TWA4XP treatments. Enhancing acetogenesis by supplementation with an acetogen strain and/or yeast cells may be an approach to mitigate methane, by targeting proper acetogens such as uncultured low-E. limosum-like acetogens.

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Acetogenic Prokaryotes

Cited by 187 publications

References 453 publications

Autotrophic fixation of geogenic CO<sub>2</sub> by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

Autotrophic fixation of geogenic CO<sub>2</sub> by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

Where microorganisms meet rocks in the Earth's Critical Zone

Rumen fermentation and acetogen population changes in response to an exogenous acetogen TWA4 strain and Saccharomyces cerevisiae fermentation product

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Acetogenic Prokaryotes

Cited by 187 publications

References 453 publications

Autotrophic fixation of geogenic CO&lt;sub&gt;2&lt;/sub&gt; by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

Autotrophic fixation of geogenic CO&lt;sub&gt;2&lt;/sub&gt; by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

Where microorganisms meet rocks in the Earth's Critical Zone

Rumen fermentation and acetogen population changes in response to an exogenous acetogen TWA4 strain and Saccharomyces cerevisiae fermentation product

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Autotrophic fixation of geogenic CO<sub>2</sub> by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

Autotrophic fixation of geogenic CO<sub>2</sub> by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette