Anaerobic microbial biogeochemistry in a northern bog: Acetate as a dominant metabolic end product

Duddleston, Khrystyne N.; Kinney, Monica A.; Kiene, Ronald P.; Hines, Mark E.

doi:10.1029/2001gb001402

Cited by 147 publications

(143 citation statements)

References 33 publications

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“…This phenomenon is confirmed in controlled anaerobic incubations of thawing permafrost soils, in which alternate inorganic TEAs are known to be low (Hodgkins et al , 2015. Hypothesized explanations for this puzzle include the presence of organic TEAs (Bridgham et al 1998), the buildup of fermentation by-products such as acetate (which, intriguingly, is often not consumed by acetoclastic methanogens in bogs) (Duddleston et al 2002, Keller & Bridgham 2007, and the presence of phenols or aromatic substances that may have an antibiotic or toxic effect on microbes (Bridgham et al 2013, Hines et al 2008, Ye et al 2012). …”

Section: Figurementioning

confidence: 71%

Permafrost Meta-Omics and Climate Change

Mackelprang

Saleska²,

Jacobsen

et al. 2016

Annu. Rev. Earth Planet. Sci.

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Permanently frozen soil, or permafrost, covers a large portion of the Earth's terrestrial surface and represents a unique environment for cold-adapted microorganisms. As permafrost thaws, previously protected organic matter becomes available for microbial degradation. Microbes that decompose soil carbon produce carbon dioxide and other greenhouse gases, contributing substantially to climate change. Next-generation sequencing and other -omics technologies offer opportunities to discover the mechanisms by which microbial communities regulate the loss of carbon and the emission of greenhouse gases from thawing permafrost regions. Analysis of nucleic acids and proteins taken directly from permafrost-associated soils has provided new insights into microbial communities and their functions in Arctic environments that are increasingly impacted by climate change. In this article we review current information from various molecular -omics studies on permafrost microbial ecology and explore the relevance of these insights to our current understanding of the dynamics of permafrost loss due to climate change.

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Section: Figurementioning

confidence: 71%

Permafrost Meta-Omics and Climate Change

Mackelprang

Saleska²,

Jacobsen

et al. 2016

Annu. Rev. Earth Planet. Sci.

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“…It can exceed methane as an end product of anaerobic metabolism in wetlands, reaching concentrations of up to 1 mM (16). Like methane, acetate diffuses upwards from anaerobic zones to an aerobic surface sink, where Methylocella is active (16).…”

Section: Discussionmentioning

confidence: 99%

Methylocella Species Are Facultatively Methanotrophic

2005

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All aerobic methanotrophic bacteria described to date are unable to grow on substrates containing carboncarbon bonds. Here we demonstrate that members of the recently discovered genus Methylocella are an exception to this. These bacteria are able to use as their sole energy source the one-carbon compounds methane and methanol, as well as the multicarbon compounds acetate, pyruvate, succinate, malate, and ethanol. To conclusively verify facultative growth, acetate and methane were used as model substrates in growth experiments with the type strain Methylocella silvestris BL2. Quantitative real-time PCR targeting the mmoX gene, which encodes a subunit of soluble methane monooxygenase, showed that copies of this gene increased in parallel with cell counts during growth on either acetate or methane as the sole substrate. This verified that cells possessing the genetic basis of methane oxidation grew on acetate as well as methane. Cloning of 16S rRNA genes and fluorescence in situ hybridization with strain-specific and genus-specific oligonucleotide probes detected no contaminants in cultures. The growth rate and carbon conversion efficiency were higher on acetate than on methane, and when both substrates were provided in excess, acetate was preferably used and methane oxidation was shut down. Our data demonstrate that not all methanotrophic bacteria are limited to growing on one-carbon compounds. This could have major implications for understanding the factors controlling methane fluxes in the environment.Aerobic methanotrophic bacteria occupy a key position in the global methane cycle. In aerobic interfaces of flooded soils and wetlands their activity limits potential methane efflux to the atmosphere, and in well-aerated upland soils they consume atmospheric methane directly (8, 25). The 11 described genera of methanotrophic bacteria include species with diverse environmental tolerances and biochemical properties, but one trait considered common to all is the inability to grow on substrates containing carbon-carbon bonds (5,18,20). Growth is limited to methane, methanol, and in some cases formate, formaldehyde, and methylamines (5). Experiments with 14 C-labeled substrates have shown that small amounts of some organic acids can also be assimilated during exponential growth on one-carbon substrates. However, this accounts for at most 5 to 10% of the total C assimilation, no energy is gained, and no growth occurs on these compounds alone (18).Recently, the new methanotrophic species Methylocella palustris (13, 14), Methylocella silvestris (17), and Methylocella tundrae (9) were isolated from acidic peat, forest, and tundra soils, respectively. Together with Methylocapsa acidiphila (12), these species form a distinct taxonomic cluster of acidophilic, methanotrophic bacteria. These belong to the Alphaproteobacteria (type II methanotrophs) but are not monophyletic with the previously known type II methanotrophs of the genera Methylosinus and Methylocystis. Instead, Methylocella species are closely related to the nonmeth...

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“…In some peat ecosystems, however, acetoclastic methanogenesis is apparently impeded and CH 4 is mainly produced from H 2 /CO 2 (Lansdown et al, 1992;Horn et al, 2003;Metje and Frenzel, 2005;Prater et al, 2007). In Alaskan peatland acetate was found to accumulate instead of being further converted to CH 4 (Duddleston et al, 2002). In a Finnish peat bog part of the acetate was found to be further converted to butyrate (Metje and Frenzel, 2005).…”

Section: Introductionmentioning

confidence: 99%

Stable carbon isotope fractionation during methanogenesis in three boreal peatland ecosystems

2010

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Abstract. The degradation of organic matter to CH 4 and CO 2 was investigated in three different boreal peatland systems in Finland, a mesotrophic fen (MES), an oligotrophic fen (OLI), and an ombrotrophic peat (OMB). MES had similar production rates of CO 2 and CH 4 , but the two nutrientpoor peatlands (OLI and OMB) produced in general more CO 2 than CH 4 . δ 13 C analysis of CH 4 and CO 2 in the presence and absence methyl fluoride (CH 3 F), an inhibitor of acetoclastic methanogenesis, showed that CH 4 was predominantly produced by hydrogenotrophic methanogenesis and that acetoclastic methanogenesis only played an important role in MES. These results, together with our observations concerning the collective inhibition of CH 4 and CO 2 production rates by CH 3 F, indicate that organic matter was degraded through different paths in the mesotrophic and the nutrient-poor peatlands. In the mesotrophic fen, the major process is canonical fermentation followed by acetoclastic and hydrogenotrophic methanogenesis, while in the nutrient-poor peat, organic matter was apparently degraded to a large extent by a different path which finally involved hydrogenotrophic methanogenesis. Our data suggest that degradation of organic substances in the oligotrophic environments was incomplete and involved the use of organic compounds as oxidants.

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Anaerobic microbial biogeochemistry in a northern bog: Acetate as a dominant metabolic end product

Cited by 147 publications

References 33 publications

Permafrost Meta-Omics and Climate Change

Permafrost Meta-Omics and Climate Change

Methylocella Species Are Facultatively Methanotrophic

Stable carbon isotope fractionation during methanogenesis in three boreal peatland ecosystems

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