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Methanogenesis Biochemistry

  1. Daniel J Lessner

Published Online: 15 DEC 2009

DOI: 10.1002/9780470015902.a0000573.pub2

eLS

eLS

How to Cite

Lessner, D. J. 2009. Methanogenesis Biochemistry. eLS. .

Author Information

  1. The University of Arkansas-Fayetteville, Fayetteville, Arkansas, USA

Publication History

  1. Published Online: 15 DEC 2009

Abstract

Methanogenesis is the biological production of methane mediated by anaerobic microorganisms from the Archaea domain commonly called methanogens. The production of methane is the energy-yielding metabolism of methanogens and is unique to these organisms. Methane is produced by three major pathways: (1) reduction of carbon dioxide, (2) fermentation of acetate and (3) dismutation of methanol or methylamines. All three pathways have in common the demethylation of methyl–coenzyme M to methane and the reduction of the heterodisulfide of coenzyme M and coenzyme B catalysed by methyl–coenzyme M and heterodisulfide reductases. Investigations of the biochemistry of the pathways have revealed novel enzymes with metal and cofactor requirements that have introduced new principles of biochemistry.

Key Concepts

  • Methanogenesis is the final step in the biological decomposition of biomass in the absence of oxygen.

  • Approximately 70% of biologically produced methane originates from conversion of the methyl group of acetate to methane.

  • The pathway of methanogenesis involves enzymes with novel cofactor and metal requirements.

  • Nickel is an essential metal that is found in the active site of carbon monoxide dehydrogenase, hydrogenase, and methyl–coenzyme M reductase, an enzyme which is common to all methanogenic pathways.

  • Methyltransferases involved in the metabolism of methylamines by Methanosarcina species contain pyyrolysine, the 22nd amino acid.

  • Comparative genomics combined with biochemical analyses have revealed variations in the enzymes involved in the energy-conservation steps in methanogens.

  • Energy conservation in methanogens is linked to the generation of a chemical gradient that drives ATP synthesis by an ATP synthase.

Keywords:

  • anaerobic;
  • archaea;
  • cofactors;
  • nickel;
  • bioenergetics