identifier: METPO:1002006 label: Syntrophy definition: A metabolism in which the metabolism of one species is thermodynamically dependent on the removal of its products by another species. definition_source: DOI:10.1038/nrmicro2166 trait_category: METABOLISM term_kind: CLASS mapping_status: REVIEWED parent_traits: - METPO:1000060 created_by: Jed Dongjin Kim-Ozaeta evidence: - reference: DOI:10.1038/nrmicro2166 snippet: Interspecies electron transfer is a key process notes: Review supports hydrogen/formate-mediated electron transfer in syntrophic communities. canonical_examples: - taxon_id: NCBITaxon:863 taxon_label: Syntrophomonas wolfei note: "Type species of Syntrophomonas; original syntrophic fatty-acid oxidiser (coculture with Methanospirillum hungatei)." reference: https://pmc.ncbi.nlm.nih.gov/articles/PMC243852/ causal_graphs: - graph_id: syntrophy_interspecies_electron_transfer title: Syntrophy interspecies electron transfer mechanism description: DOI-backed graph for product removal and electron transfer between fermenting syntrophs and methanogenic partners. nodes: - node_id: syntrophy_trait label: Syntrophy node_type: TRAIT grounding: METPO:1002006 description: Thermodynamically coupled metabolism between partner organisms. - node_id: syntrophic_product_formation label: syntrophic product formation node_type: BIOLOGICAL_PROCESS description: Product-forming metabolism that depends on product removal by a partner. - node_id: methanogenic_product_consumption label: methanogenic product consumption node_type: BIOLOGICAL_PROCESS description: Hydrogen- or formate-consuming methanogenic partner metabolism. - node_id: molecular_hydrogen label: molecular hydrogen node_type: CHEMICAL grounding: CHEBI:18276 description: Diffusible interspecies electron carrier. - node_id: formate label: formate node_type: CHEMICAL grounding: CHEBI:15740 description: Diffusible interspecies electron carrier. - node_id: low_hydrogen_condition label: low hydrogen condition node_type: ENVIRONMENTAL_FACTOR description: Product concentration state that permits otherwise unfavorable syntrophic metabolism. - node_id: methanogenesis label: methanogenesis node_type: PATHWAY grounding: METPO:1000844 description: Hydrogen- or formate-consuming methane-producing pathway. - node_id: interspecies_hydrogen_transfer label: interspecies hydrogen transfer node_type: BIOLOGICAL_PROCESS description: H2-mediated interspecies electron transfer (MIET) between syntrophic partners. - node_id: interspecies_formate_transfer label: interspecies formate transfer node_type: BIOLOGICAL_PROCESS description: Formate-mediated interspecies electron transfer between syntrophic partners. - node_id: low_hydrogen_partial_pressure label: low hydrogen partial pressure node_type: ENVIRONMENTAL_FACTOR description: Extremely low H2 partial pressure required for thermodynamic feasibility of MIET. - node_id: formate_dehydrogenase_complex label: formate dehydrogenase complex node_type: GENE_OR_PROTEIN description: Enzyme complex producing/consuming formate in syntrophic formate transfer. - node_id: hydrogenase_complex label: hydrogenase complex node_type: GENE_OR_PROTEIN description: Enzyme complex producing/consuming H2 in syntrophic hydrogen transfer. - node_id: direct_interspecies_electron_transfer label: direct interspecies electron transfer node_type: BIOLOGICAL_PROCESS description: 'DIET: electron transfer via conductive structures without soluble H2/formate intermediates.' - node_id: hydrogen_pressure_inhibition label: hydrogen pressure inhibition node_type: STATE description: Thermodynamic inhibition of syntrophic oxidation by elevated H2 partial pressure. - node_id: conductive_pili label: conductive pili (e-pili) node_type: CELLULAR_LOCALIZATION description: Electrically conductive pili that serve as a DIET conduit. - node_id: multiheme_cytochromes label: multiheme c-type cytochromes node_type: GENE_OR_PROTEIN description: Outer-surface multiheme c-type cytochromes mediating DIET. edges: - subject: syntrophy_trait predicate: requires partner interaction object: methanogenic_product_consumption description: Syntrophic metabolism depends on a partner that consumes products. evidence: - reference: DOI:10.1038/nrmicro2166 snippet: metabolic abilities of their syntrophic partner notes: Supports partner dependence in syntrophic communities. - subject: syntrophic_product_formation predicate: transfers electrons via object: molecular_hydrogen description: Hydrogen can carry reducing equivalents between syntrophic partners. evidence: - reference: DOI:10.1038/nrmicro2166 snippet: Hydrogen and formate are key components notes: Supports hydrogen as a key interspecies electron-transfer carrier. predicate_id: METPO:2007600 - subject: syntrophic_product_formation predicate: transfers electrons via object: formate description: Formate can carry reducing equivalents between syntrophic partners. evidence: - reference: DOI:10.1038/nrmicro2166 snippet: transfer of hydrogen and formate notes: Supports formate-mediated interspecies electron transfer. predicate_id: METPO:2007600 - subject: methanogenic_product_consumption predicate: consumes object: molecular_hydrogen description: Methanogens keep hydrogen concentrations low enough for syntrophic metabolism. evidence: - reference: DOI:10.1038/nrmicro2166 snippet: low hydrogen concentrations, which are created by the methanogen notes: Supports product removal by methanogens as a thermodynamic driver. predicate_id: biolink:consumes - subject: methanogenic_product_consumption predicate: creates object: low_hydrogen_condition description: Hydrogen consumption creates the product-removal condition needed by the syntroph. evidence: - reference: DOI:10.1038/nrmicro2166 snippet: live at the limits of what is thermodynamically possible notes: Supports the thermodynamic constraint that product removal relieves. predicate_id: biolink:produces - subject: molecular_hydrogen predicate: participates in object: methanogenesis description: Hydrogen can feed methanogenesis in syntrophic communities. evidence: - reference: DOI:10.1038/nrmicro2166 snippet: syntrophic methanogenic communities notes: Supports hydrogen-linked electron flow into methanogenic partners. predicate_id: biolink:participates_in - subject: low_hydrogen_partial_pressure predicate: enables object: interspecies_hydrogen_transfer description: H2-mediated transfer is thermodynamically feasible only at extremely low H2 partial pressure. evidence: - reference: DOI:10.3390/fermentation9050467 notes: H2-mediated transfer thermodynamically feasible only when H2 < 10^-4 atm. predicate_id: RO:0002327 - subject: interspecies_hydrogen_transfer predicate: mediates object: syntrophy_trait description: Interspecies hydrogen transfer is a core mechanistic sub-process of syntrophy. evidence: - reference: DOI:10.3390/fermentation9050467 notes: H2-mediated MIET (IHT) is a main interspecies electron transfer mode relevant to syntrophy. - subject: interspecies_formate_transfer predicate: mediates object: syntrophy_trait description: Interspecies formate transfer is a core mechanistic sub-process of syntrophy. evidence: - reference: DOI:10.1093/femsre/fuab057 notes: Interspecies formate transfer is one of three IET mechanisms in syntrophic propionate oxidation. - subject: formate_dehydrogenase_complex predicate: mediates object: interspecies_formate_transfer description: Formate dehydrogenases provide the enzymatic basis for formate production/consumption in syntrophy. evidence: - reference: DOI:10.1186/s40168-020-00885-y notes: Formate dehydrogenases and formate transporters expressed by FA-degrading syntrophic species. - subject: hydrogenase_complex predicate: mediates object: interspecies_hydrogen_transfer description: Hydrogenases provide the enzymatic basis for H2 production/consumption in syntrophy. evidence: - reference: DOI:10.1038/s41396-023-01504-y notes: Hydrogen-mediated transfer supported by expression of hydrogenases in syntrophic communities. - subject: direct_interspecies_electron_transfer predicate: bypasses object: hydrogen_pressure_inhibition description: DIET can overcome inhibition by hydrogen pressure, enabling syntrophy without soluble carriers. evidence: - reference: DOI:10.3390/fermentation9100884 notes: DIET can overcome the inhibition of hydrogen pressure and formate concentration. - subject: conductive_pili predicate: mediates object: direct_interspecies_electron_transfer description: Conductive pili (e-pili) are a canonical DIET conduit. evidence: - reference: DOI:10.1134/S0026261720020101 notes: DIET occurs via conductive pili (e-pili). - subject: multiheme_cytochromes predicate: mediates object: direct_interspecies_electron_transfer description: Outer-surface multiheme c-type cytochromes are a core DIET redox conduit. evidence: - reference: DOI:10.3390/life14050591 notes: DIET operates via outer-surface c-type cytochromes. curation_history: - timestamp: '2026-05-05T01:35:46.936190+00:00' curator: seed_from_metpo action: SEEDED_FROM_METPO changes: imported from data/raw/metpo.owl (CLASS) llm_assisted: false - timestamp: '2026-05-08T00:00:00-07:00' curator: codex action: ADDED_CAUSAL_GRAPH changes: Added DOI-backed causal graph for hydrogen/formate interspecies electron transfer and methanogenic product removal in syntrophy. llm_assisted: true - timestamp: '2026-05-20T05:49:24Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (biolink:consumes×1). llm_assisted: true - timestamp: '2026-05-26T05:00:48Z' curator: claude action: RENAME_PREDICATE_LABELS changes: 'Renamed 1 causal-edge predicate label(s) to align with existing groundings: input to → participates in ×1.' llm_assisted: true - timestamp: '2026-05-26T05:00:50Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (biolink:participates_in×1). llm_assisted: true - timestamp: '2026-06-13T21:03:26Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (biolink:produces×1). llm_assisted: true - timestamp: '2026-06-14T07:26:19Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (METPO:2007600×2). llm_assisted: true - timestamp: '2026-06-23T00:00:00Z' curator: claude action: ENRICH_CAUSAL_GRAPH changes: Added 8 evidence-backed generic edges (9 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