identifier: traitmech:000033 label: anaerobic oxidation of methane definition: A metabolism in which methane is oxidized under anoxic conditions, classically coupled to sulfate reduction and mediated by consortia of anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria. It is a major sink for methane in marine sediments. definition_source: DOI:10.1038/35036572 trait_category: METABOLISM term_kind: CLASS mapping_status: REVIEWED parent_traits: - METPO:1000802 synonyms: - synonym_text: AOM synonym_type: EXACT_SYNONYM source: DOI:10.1038/35036572 - synonym_text: anaerobic methanotrophy synonym_type: RELATED_SYNONYM source: DOI:10.3389/fmars.2025.1609892 evidence: - reference: DOI:10.1038/35036572 notes: Boetius et al. described the marine microbial consortium of ANME archaea and sulfate-reducing bacteria mediating anaerobic oxidation of methane. - reference: DOI:10.3389/fmars.2025.1609892 notes: Review of AOM in marine sediments supports sulfate- and metal-coupled anaerobic methane oxidation as a major methane sink. canonical_examples: - taxon_id: NCBITaxon:1392998 taxon_label: Candidatus Methanoperedens nitratireducens note: "Canonical nitrate-dependent ANME archaeon performing anaerobic oxidation of methane (ANME-2d). Candidatus taxon (no validly published name)." reference: https://pubmed.ncbi.nlm.nih.gov/36635574/ causal_graphs: - graph_id: aom_anme_sulfate_consortium title: AOM couples methane oxidation to sulfate reduction in ANME-SRB consortia description: Evidence-backed causal sketch linking anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria to coupled methane oxidation and sulfate reduction. nodes: - node_id: aom_trait label: anaerobic oxidation of methane node_type: TRAIT grounding: traitmech:000033 description: Anaerobic methane oxidation, classically coupled to sulfate reduction. - node_id: methane label: methane node_type: CHEMICAL grounding: CHEBI:16183 description: Substrate oxidized under anoxic conditions. - node_id: sulfate label: sulfate node_type: CHEMICAL grounding: CHEBI:16189 description: Terminal electron acceptor for AOM. - node_id: reverse_methanogenesis label: reverse methanogenesis node_type: PATHWAY description: Core pathway by which methane is activated and oxidized to CO2 during AOM. - node_id: mcr label: methyl-coenzyme M reductase (MCR) node_type: GENE_OR_PROTEIN description: Enzyme that activates methane (to methyl-S-CoM) as the initial step of AOM. - node_id: diet label: direct interspecies electron transfer (DIET) node_type: BIOLOGICAL_PROCESS description: Electron transfer from ANME to sulfate-reducing bacteria via conserved outer-membrane complexes in sulfate-AOM syntrophy. - node_id: nitrate label: nitrate node_type: CHEMICAL grounding: CHEBI:17632 description: Terminal electron acceptor for nitrate-dependent AOM. - node_id: nitrite label: nitrite node_type: CHEMICAL grounding: CHEBI:16301 description: Terminal electron acceptor for nitrite-dependent AOM. edges: - subject: methane predicate: oxidized to object: sulfate description: Methane oxidation is coupled to sulfate reduction in the ANME-SRB consortium. evidence: - reference: DOI:10.1038/35036572 notes: Boetius et al. described the marine ANME-SRB consortium mediating AOM. predicate_id: METPO:2007405 - subject: aom_trait predicate: associated with object: methane description: AOM is a major biological sink for methane in anoxic sediments. evidence: - reference: DOI:10.3389/fmars.2025.1609892 notes: AOM review supports sulfate- and metal-coupled methane oxidation as a major methane sink. predicate_id: biolink:associated_with - subject: aom_trait predicate: has core pathway object: reverse_methanogenesis description: AOM proceeds via the reverse methanogenesis pathway, oxidizing methane to CO2. evidence: - reference: DOI:10.3390/fermentation9070645 notes: 'AOM proceeds via the reverse methanogenesis pathway: CH4 is converted to methyl-S-CoM by Mcr then oxidized to CO2.' - subject: mcr predicate: catalyzes initial step of object: aom_trait description: MCR activates methane as the initial step of AOM (reverse methanogenesis). evidence: - reference: DOI:10.1021/acs.est.3c07197 notes: Methane activation by methyl-coenzyme M reductase (MCR) is the methane-activation step in reverse methanogenesis. - subject: sulfate predicate: serves as terminal electron acceptor for object: aom_trait description: Sulfate is the terminal electron acceptor in sulfate-coupled AOM. evidence: - reference: DOI:10.1371/journal.pbio.3002292 notes: Sulfate-coupled AOM is performed by consortia of ANME in obligate syntrophic partnership with sulfate-reducing bacteria. - subject: diet predicate: enables object: aom_trait description: DIET via conserved ANME-to-SRB outer-membrane complexes enables sulfate-coupled AOM syntrophy. evidence: - reference: DOI:10.1371/journal.pbio.3002292 notes: Protein complexes involved in direct interspecies electron transfer (DIET) from ANME to the SRB outer membrane are conserved. predicate_id: RO:0002327 - subject: nitrate predicate: serves as terminal electron acceptor for object: aom_trait description: Nitrate serves as terminal electron acceptor in nitrate-dependent AOM via reverse methanogenesis. evidence: - reference: DOI:10.1021/acs.est.3c07197 notes: Methane oxidation via a reverse methanogenesis pathway coupled to nitrate reduction to nitrite. - subject: nitrite predicate: serves as terminal electron acceptor for object: aom_trait description: Nitrite serves as terminal electron acceptor in nitrite-dependent AOM (n-DAMO). evidence: - reference: DOI:10.1021/acs.est.3c07197 notes: Nitrite-dependent methane oxidation reduces nitrite to nitric oxide in an intra-aerobic pathway. curation_history: - timestamp: '2026-05-30T00:00:00Z' curator: claude action: PROPOSED_FROM_RESEARCH changes: Proposed candidate METABOLISM trait (anaerobic oxidation of methane) from literature research; complements the existing methanogenesis class (the reverse process). llm_assisted: true - timestamp: '2026-06-10T14:00:00Z' curator: claude action: CURATED_CAUSAL_GRAPH changes: Added evidence-backed causal graph (ANME-SRB AOM consortium) with CHEBI node groundings and METPO/biolink predicate groundings; promoted PROPOSED to REVIEWED. llm_assisted: true - timestamp: '2026-06-23T00:00:00Z' curator: claude action: ENRICH_CAUSAL_GRAPH changes: Added 6 evidence-backed generic edges (5 new nodes) from the deep-research report. llm_assisted: true - timestamp: '2026-06-24T17:21:12Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002327×1). llm_assisted: true