identifier: METPO:1002003
label: Cable bacteria metabolism
definition: A metabolism in which electrons are transferred over centimeter-scale
  distances through multicellular filaments.
definition_source: DOI:10.1073/pnas.1800367115
trait_category: METABOLISM
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000060
evidence:
- reference: DOI:10.1073/pnas.1800367115
  snippet: Long-distance electron transport in individual, living cable bacteria
  notes: Study directly demonstrates long-distance electron transport in cable bacteria.
- reference: DOI:10.3389/fmars.2017.00028
  snippet: oxidize sulfide in deeper sediments
  notes: Study supports electrogenic sulfur oxidation with sulfide oxidation and oxygen
    reduction zones.
canonical_examples:
- taxon_id: NCBITaxon:1859128
  taxon_label: Candidatus Electrothrix
  note: "Marine cable bacteria conducting electrons over centimetre distances along filaments (long-distance electron transport)."
  reference: PMID:27324572
causal_graphs:
- graph_id: cable_bacteria_long_distance_electron_transport
  title: Cable bacteria long-distance electron transport
  description: DOI-backed graph linking sulfide oxidation, conductive multicellular
    filaments, centimeter-scale electron transport, and oxygen reduction.
  nodes:
  - node_id: cable_bacteria_trait
    label: Cable bacteria metabolism
    node_type: TRAIT
    grounding: METPO:1002003
    description: Multicellular filament metabolism involving long-distance electron
      transport.
  - node_id: sulfidic_sediment_zone
    label: sulfidic sediment zone
    node_type: ENVIRONMENTAL_FACTOR
    description: Anoxic sediment layer containing sulfide.
  - node_id: oxic_sediment_zone
    label: oxic sediment zone
    node_type: ENVIRONMENTAL_FACTOR
    description: Surface sediment layer containing oxygen.
  - node_id: sulfide
    label: sulfide
    node_type: CHEMICAL
    description: Electron donor oxidized by anodic cable bacteria cells.
    grounding: CHEBI:15138
  - node_id: oxygen
    label: molecular oxygen
    node_type: CHEMICAL
    grounding: CHEBI:15379
    description: Electron acceptor reduced by cathodic cable bacteria cells.
  - node_id: multicellular_filament
    label: multicellular filament
    node_type: CELLULAR_LOCALIZATION
    description: Chain of cable bacteria cells spanning redox-separated zones.
  - node_id: conductive_fiber_network
    label: conductive fiber network
    node_type: CELLULAR_LOCALIZATION
    description: Conductive cell-envelope structure supporting long-distance electron
      transport.
  - node_id: long_distance_electron_transport
    label: long-distance electron transport
    node_type: BIOLOGICAL_PROCESS
    description: Electron transport across millimeter-to-centimeter distances.
  - node_id: electrogenic_sulfur_oxidation
    label: electrogenic sulfur oxidation
    node_type: BIOLOGICAL_PROCESS
    description: Spatially separated sulfide oxidation and oxygen reduction connected
      by electrical current.
  - node_id: sulfate
    label: sulfate
    node_type: CHEMICAL
    grounding: CHEBI:16189
    description: Oxidized sulfur product.
  - node_id: cell_envelope
    label: cell envelope
    node_type: CELLULAR_LOCALIZATION
    description: Outer cell-envelope structure in which conductive fibers are embedded.
    grounding: GO:0030313
  - node_id: nickel_cofactor
    label: sulfur-ligated nickel cofactor
    node_type: CHEMICAL
    description: Novel nickel-containing cofactor (NiBiD) associated with the conductive
      fibers.
  - node_id: cytochrome_redox_gradient
    label: cytochrome redox gradient
    node_type: STATE
    description: Redox state gradient of cytochromes maintained along the conductive
      filament.
  - node_id: sulfur_oxidation_pathway
    label: Dsr-Apr-Qmo-Sqr-Psr/Phs sulfur oxidation pathway
    node_type: PATHWAY
    description: Genomically predicted dissimilatory sulfur oxidation pathway supporting
      sulfide oxidation.
  edges:
  - subject: cable_bacteria_trait
    predicate: occurs in
    object: multicellular_filament
    description: Cable bacteria metabolism is performed by long multicellular filaments.
    evidence:
    - reference: DOI:10.1073/pnas.1800367115
      snippet: centimeter-long, multicellular filamentous bacteria
      notes: Supports multicellular filament organization.
    predicate_id: biolink:occurs_in
  - subject: sulfidic_sediment_zone
    predicate: provides electron donor
    object: sulfide
    description: Deeper sulfidic sediment provides sulfide for oxidation.
    evidence:
    - reference: DOI:10.3389/fmars.2017.00028
      snippet: oxidize sulfide in deeper sediments
      notes: Supports sulfide oxidation in deeper sediment.
  - subject: oxic_sediment_zone
    predicate: provides electron acceptor
    object: oxygen
    description: The oxic sediment zone provides oxygen for electron acceptance.
    evidence:
    - reference: DOI:10.3389/fmars.2017.00028
      snippet: oxic zone
      notes: Supports electron transfer from deeper sediments to oxic zones.
  - subject: conductive_fiber_network
    predicate: located in
    object: multicellular_filament
    description: Conductive fibers run along the cable bacteria filament.
    evidence:
    - reference: DOI:10.1073/pnas.1800367115
      snippet: conductive fibers
      notes: Supports conductive filament structures.
    predicate_id: biolink:located_in
  - subject: sulfide
    predicate: oxidized during
    object: electrogenic_sulfur_oxidation
    description: Sulfide oxidation supplies electrons to the cable.
    evidence:
    - reference: DOI:10.3389/fmars.2017.00028
      snippet: Electrogenic Sulfur Oxidation
      notes: Supports sulfide oxidation as the anodic process.
  - subject: electrogenic_sulfur_oxidation
    predicate: produces
    object: sulfate
    description: Sulfide oxidation can yield sulfate.
    evidence:
    - reference: DOI:10.3389/fmars.2017.00028
      snippet: sulfide
      notes: Source supports electrogenic sulfide oxidation; sulfate is the oxidized
        sulfur end product in the modeled sulfur oxidation route.
    predicate_id: METPO:2000202
  - subject: conductive_fiber_network
    predicate: mediates
    object: long_distance_electron_transport
    description: Conductive fibers mediate long-distance electron transport.
    evidence:
    - reference: DOI:10.1073/pnas.1800367115
      snippet: long-distance electron transport
      notes: Supports electron transport over millimeter-to-centimeter distances.
  - subject: long_distance_electron_transport
    predicate: transfers electrons to
    object: oxygen
    description: Long-distance electron transport connects sulfide oxidation to oxygen
      reduction.
    evidence:
    - reference: DOI:10.1073/pnas.1800367115
      snippet: sulfide as an electron source at one end and oxygen as an electron
        acceptor at the other
      notes: Supports redox-separated sulfide-to-oxygen electron flow.
    predicate_id: METPO:2007403
  - subject: oxygen
    predicate: reduced during
    object: electrogenic_sulfur_oxidation
    description: Oxygen reduction is the cathodic half reaction in many cable bacteria
      systems.
    evidence:
    - reference: DOI:10.3389/fmars.2017.00028
      snippet: reduction of oxygen
      notes: Supports oxygen reduction coupled to sulfide oxidation.
  - subject: conductive_fiber_network
    predicate: part of
    object: cell_envelope
    description: Conductive fibers are embedded in and run along the cell envelope.
    evidence:
    - reference: DOI:10.1186/s12864-024-10594-7
      notes: Fibers are "embedded in the cell envelope" and run along filament length.
    predicate_id: biolink:part_of
  - subject: nickel_cofactor
    predicate: component of
    object: conductive_fiber_network
    description: A sulfur-ligated nickel cofactor is a component of the conductive
      fibers.
    evidence:
    - reference: DOI:10.1186/s12864-024-10594-7
      notes: Conductive fibers "harbour a novel nickel-containing cofactor"; Raman/extraction
        data show Ni-cofactor-associated modes.
  - subject: nickel_cofactor
    predicate: mediates
    object: long_distance_electron_transport
    description: The nickel cofactor supports/mediates long-range electron transport.
    evidence:
    - reference: DOI:10.3389/fmicb.2024.1208033
      notes: Authors link a "Ni-based, long-range electron transport pathway" to the
        cofactor; orientation-dependent Raman aligns cofactor with electron path.
  - subject: long_distance_electron_transport
    predicate: maintains
    object: cytochrome_redox_gradient
    description: An intact electrical connection along the filament maintains the
      cytochrome redox gradient.
    evidence:
    - reference: DOI:10.1073/pnas.1800367115
      notes: A redox gradient along filaments immediately broke down upon removal
        of oxygen or laser cutting, showing dependence on intact long-distance transport.
  - subject: sulfur_oxidation_pathway
    predicate: supports
    object: electrogenic_sulfur_oxidation
    description: The Dsr-Apr-Qmo-Sqr-Psr/Phs pathway supports sulfide oxidation metabolism.
    evidence:
    - reference: DOI:10.1186/s12864-024-10594-7
      notes: Comparative genomics predicts sulfur oxidation through a Dsr-Apr-Qmo-Sqr-Psr/Phs
        pathway with DsrMKJOPG across closed genomes.
curation_history:
- timestamp: '2026-05-05T01:35:46.935199+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 multicellular cable filaments, conductive
    fibers, redox-separated sulfide oxidation and oxygen reduction, and long-distance
    electron transport.
  llm_assisted: true
- timestamp: '2026-05-20T03:35:30Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2000202×1).
  llm_assisted: true
- timestamp: '2026-05-20T05:49:24Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (biolink:occurs_in×1, biolink:located_in×1).
  llm_assisted: true
- timestamp: '2026-05-23T21:30:06Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2007403×1).
  llm_assisted: true
- timestamp: '2026-05-24T04:38:00Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (CHEBI:15138×1).
  llm_assisted: true
- timestamp: '2026-06-23T00:00:00Z'
  curator: claude
  action: ENRICH_CAUSAL_GRAPH
  changes: Added 5 evidence-backed generic edges (4 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
    (biolink:part_of×1).
  llm_assisted: true
- timestamp: '2026-06-24T17:23:32Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (GO:0030313×1).
  llm_assisted: true