New perspectives on anaerobic methane oxidation.

David L Valentine,William S Reeburgh

doi:10.1046/j.1462-2920.2000.00135.x

David L Valentine, William S Reeburgh

Open Access

https://doi.org/10.1046/j.1462-2920.2000.00135.x

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Journal: Environmental Microbiology	Publication Date: Oct 1, 2000
Citations: 477	License type: cc-by

Affiliation: University of California, Irvine

Abstract

Anaerobic methane oxidation is a globally important but poorly understood process. Four lines of evidence have recently improved our understanding of this process. First, studies of recent marine sediments indicate that a consortium of methanogens and sulphate-reducing bacteria are responsible for anaerobic methane oxidation; a mechanism of 'reverse methanogenesis' was proposed, based on the principle of interspecies hydrogen transfer. Second, studies of known methanogens under low hydrogen and high methane conditions were unable to induce methane oxidation, indicating that 'reverse methanogenesis' is not a widespread process in methanogens. Third, lipid biomarker studies detected isotopically depleted archaeal and bacterial biomarkers from marine methane vents, and indicate that Archaea are the primary consumers of methane. Finally, phylogenetic studies indicate that only specific groups of Archaea and SRB are involved in methane oxidation. This review integrates results from these recent studies to constrain the responsible mechanisms.

Highlights

Methane oxidation in anoxic environments is microbially mediated and of global significance
A variety of different environments exist in which sulphate-dependent methane oxidation (SDMO) is thought to occur, including recent marine sediments, methane seeps and vents, anoxic waters, soda lakes and deep continental margin sediments
Three lines of evidence have traditionally been used to support the existence of SDMO: (i) diagenetic models of methane concentration profiles in anoxic sediments and water columns (Barnes and Goldberg, 1976; Reeburgh, 1976; Martens and Berner, 1977; Reeburgh and Heggie, 1977; Alperin and Reeburgh, 1984); (ii) tracer measurements using [14C]CH4, [3H]-CH4 or [35S]-SO42± (Reeburgh, 1980; Devol and Ahmed, 1981; Iversen and Blackburn, 1981; Devol, 1983; Iversen and Jùrgensen, 1985; Iversen et al, 1987; Ward et al, 1987; 1989; Alperin, 1989; Reeburgh et al, 1991; Joye et al, 1999); and (iii) stable isotope distributions (Oremland and DesMarais, 1983; Whiticar et al, 1986; Oremland et al, 1987; Alperin et al, 1988; Blair and Aller, 1995; Martens et al, 1999)

Summary

Anaerobic methane oxidation is a globally important but poorly understood process. Studies of recent marine sediments indicate that a consortium of methanogens and sulphate-reducing bacteria are responsible for anaerobic methane oxidation; a mechanism ofreverse methanogenesis' was proposed, based on the principle of interspecies hydrogen transfer. Studies of known methanogens under low hydrogen and high methane conditions were unable to induce methane oxidation, indicating thatreverse methanogenesis' is not a widespread process in methanogens. Lipid biomarker studies detected isotopically depleted archaeal and bacterial biomarkers from marine methane vents, and indicate that Archaea are the primary consumers of methane. Phylogenetic studies indicate that only specific groups of Archaea and SRB are involved in methane oxidation. This review integrates results from these recent studies to constrain the responsible mechanisms

Introduction

Background

Concluding remarks