Reverse Methanogenesis and Respiration in Methanotrophic Archaea.
Anaerobic oxidation of methane (AOM) is catalyzed by anaerobic methane-oxidizing archaea (ANME) via a reverse and modified methanogenesis pathway. Methanogens can also reverse the methanogenesis pathway to oxidize methane, but only during net methane production (i.e., "trace methane oxidation"). In turn, ANME can produce methane, but only during net methane oxidation (i.e., enzymatic back flux). Net AOM is exergonic when coupled to an external electron acceptor such as sulfate (ANME-1, ANME-2abc, and ANME-3), nitrate (ANME-2d), or metal (oxides). In this review, the reversibility of the methanogenesis pathway and essential differences between ANME and methanogens are described by combining published information with domain based (meta)genome comparison of archaeal methanotrophs and selected archaea. These differences include abundances and special structure of methyl coenzyme M reductase and of multiheme cytochromes and the presence of menaquinones or methanophenazines. ANME-2a and ANME-2d can use electron acceptors other than sulfate or nitrate for AOM, respectively. Environmental studies suggest that ANME-2d are also involved in sulfate-dependent AOM. ANME-1 seem to use a different mechanism for disposal of electrons and possibly are less versatile in electron acceptors use than ANME-2. Future research will shed light on the molecular basis of reversal of the methanogenic pathway and electron transfer in different ANME types.
Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, Netherlands; Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, Netherlands; Soehngen Institute of Anaerobic Microbiology, Heyendaalseweg 135, 6525 AJ Nijmegen, Netherlands.
Peer H A
0000-0002-8049-9985
PH
Timmers
Soehngen Institute of Anaerobic Microbiology, Heyendaalseweg 135, 6525 AJ Nijmegen, Netherlands; Department of Microbiology, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, Netherlands.
Cornelia U
0000-0002-1568-8878
CU
Welte
Laboratory of Systems and Synthetic Biology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, Netherlands.
Jasper J
JJ
Koehorst
Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, Netherlands; Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, Netherlands.
Caroline M
0000-0002-3391-7742
CM
Plugge
Soehngen Institute of Anaerobic Microbiology, Heyendaalseweg 135, 6525 AJ Nijmegen, Netherlands; Department of Microbiology, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, Netherlands; TU Delft Biotechnology, Julianalaan 67, 2628 BC Delft, Netherlands.
Mike S M
MS
Jetten
Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, Netherlands; Soehngen Institute of Anaerobic Microbiology, Heyendaalseweg 135, 6525 AJ Nijmegen, Netherlands; Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
Alfons J M
AJ
Stams
D000693:Anaerobiosis; D001105:Archaea / Q000378:metabolism*; D008697:Methane / Q000378:metabolism*; D010084:Oxidation-Reduction
D008697:Methane