identifier: METPO:1000644
label: heterotrophic
definition: A trophic type in which an organism obtains carbon from organic compounds
  rather than from carbon dioxide.
definition_source: DOI:10.1016/B978-012373944-5.00083-3
trait_category: PHYSIOLOGY
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000631
synonyms:
- synonym_text: TT_heterotroph
  synonym_type: RELATED_SYNONYM
  source: metpo.owl
- synonym_text: aerobic_heterotrophy
  synonym_type: RELATED_SYNONYM
  source: metpo.owl
- synonym_text: heterotroph
  synonym_type: RELATED_SYNONYM
  source: metpo.owl
evidence:
- reference: DOI:10.1016/B978-012373944-5.00083-3
  snippet: organic compounds as the primary sources of carbon
  notes: Encyclopedia chapter supports organic compounds as heterotrophic carbon sources.
- reference: DOI:10.1021/acsomega.3c02205
  snippet: organic molecules ... carbon source
  notes: Review table supports organic molecules as carbon sources in heterotrophic
    growth modes.
- reference: PMID:9278503
  snippet: Escherichia coli K-12
  notes: 'Organism example: Escherichia coli K-12 (MG1655) is the canonical chemoorganoheterotrophic
    model bacterium that grows on diverse organic substrates (Blattner et al. 1997,
    Science, complete genome).'
canonical_examples:
- taxon_id: NCBITaxon:562
  taxon_label: Escherichia coli
  note: "organic-carbon heterotroph"
  reference: PMID:31778652
- taxon_id: NCBITaxon:1423
  taxon_label: Bacillus subtilis
  note: "soil heterotroph"
  reference: PMID:17122393
causal_graphs:
- graph_id: heterotrophic_organic_carbon_assimilation
  title: Heterotrophic organic carbon assimilation
  description: DOI-backed graph linking external organic molecules, nutrient uptake,
    catabolism, precursor metabolites, and biomass formation.
  nodes:
  - node_id: heterotrophic_trait
    label: heterotrophic
    node_type: TRAIT
    grounding: METPO:1000644
    description: Trophic type using organic compounds as carbon sources.
  - node_id: organic_molecule
    label: organic molecule
    node_type: CHEMICAL
    description: Organic carbon source such as sugars, organic acids, lipids, or amino
      acids.
    grounding: CHEBI:72695
  - node_id: nutrient_uptake
    label: nutrient uptake
    node_type: BIOLOGICAL_PROCESS
    description: Cellular import of external organic substrates.
  - node_id: catabolism
    label: catabolism
    node_type: BIOLOGICAL_PROCESS
    grounding: GO:0009056
    description: Breakdown of nutrients to supply energy and biosynthetic precursors.
  - node_id: precursor_metabolites
    label: precursor metabolites
    node_type: CHEMICAL
    description: Central metabolic intermediates used in biosynthesis.
  - node_id: anabolism
    label: anabolism
    node_type: BIOLOGICAL_PROCESS
    description: Biosynthetic conversion of precursors into cellular material.
    grounding: GO:0009058
  - node_id: biomass
    label: biomass
    node_type: CHEMICAL
    description: Cell material formed from assimilated organic carbon.
    grounding: METPO:1007501
  - node_id: glycolysis_ppp
    label: glycolysis and pentose phosphate pathway
    node_type: PATHWAY
    description: Embden-Meyerhof glycolysis and pentose phosphate pathway catabolizing
      sugars in central carbon metabolism.
  - node_id: tca_cycle
    label: TCA cycle
    node_type: PATHWAY
    description: Tricarboxylic acid cycle oxidizing imported organic carbon and generating
      biosynthetic precursors.
    grounding: GO:0006099
  - node_id: glyoxylate_cycle
    label: glyoxylate cycle
    node_type: PATHWAY
    description: Anaplerotic cycle routing acetyl-CoA, bypassing CO2-releasing TCA
      steps to enhance carbon-to-biomass conversion.
    grounding: GO:0006097
  - node_id: aerobic_respiration
    label: aerobic respiration
    node_type: BIOLOGICAL_PROCESS
    description: Energy conservation oxidizing organic substrates with oxygen as terminal
      electron acceptor.
    grounding: GO:0009060
  - node_id: fermentation
    label: fermentation
    node_type: BIOLOGICAL_PROCESS
    description: Anaerobic energy conservation via substrate-level phosphorylation
      when respiration is unavailable.
    grounding: GO:0006113
  edges:
  - subject: heterotrophic_trait
    predicate: uses carbon source
    object: organic_molecule
    description: Heterotrophy uses organic compounds as carbon sources instead of
      CO2.
    evidence:
    - reference: DOI:10.1016/B978-012373944-5.00083-3
      snippet: organic compounds as the primary sources of carbon
      notes: Supports organic compounds as heterotrophic carbon sources.
    predicate_id: METPO:2000006
  - subject: organic_molecule
    predicate: imported by
    object: nutrient_uptake
    description: Organic nutrients must be taken up before intracellular metabolism.
    evidence:
    - reference: DOI:10.1016/B978-012373944-5.00083-3
      snippet: nutrient uptake
      notes: Supports uptake as part of microbial nutrition.
  - subject: nutrient_uptake
    predicate: supplies
    object: catabolism
    description: Imported organic substrates feed catabolic metabolism.
    evidence:
    - reference: DOI:10.1016/B978-012373944-5.00083-3
      snippet: breakdown of nutrients
      notes: Supports catabolic processing of organic nutrients.
  - subject: catabolism
    predicate: produces
    object: precursor_metabolites
    description: Catabolism generates central intermediates for biosynthesis.
    evidence:
    - reference: DOI:10.1016/B978-012373944-5.00083-3
      snippet: precursor compounds for anabolism
      notes: Supports nutrient breakdown to biosynthetic precursors.
    predicate_id: METPO:2000202
  - subject: precursor_metabolites
    predicate: used by
    object: anabolism
    description: Precursor metabolites are substrates for biosynthetic pathways.
    evidence:
    - reference: DOI:10.1016/B978-012373944-5.00083-3
      snippet: anabolism
      notes: Supports biosynthetic use of catabolic precursors.
  - subject: anabolism
    predicate: produces
    object: biomass
    description: Anabolism incorporates organic carbon into biomass.
    evidence:
    - reference: DOI:10.1016/B978-012373944-5.00083-3
      snippet: incorporation of a compound into biomass
      notes: Supports assimilation of compounds into cell material.
    predicate_id: METPO:2000202
  - subject: organic_molecule
    predicate: causally enables
    object: heterotrophic_trait
    description: External organic substrates must be imported and metabolized to support
      heterotrophic growth.
    evidence:
    - reference: DOI:10.1021/acsomega.3c02205
      notes: The substrate must be imported and metabolized to produce ATP and NAD(P)H;
        minimal mechanistic requirement generalizes to heterotrophy.
  - subject: catabolism
    predicate: proceeds via
    object: glycolysis_ppp
    description: Catabolism of imported sugars proceeds via Embden-Meyerhof glycolysis
      and the pentose phosphate pathway.
    evidence:
    - reference: DOI:10.1111/raq.12700
      notes: Glucose catabolism proceeds via Embden-Meyerhof glycolysis and the pentose
        phosphate pathway; general central-metabolism support.
  - subject: tca_cycle
    predicate: produces
    object: precursor_metabolites
    description: The TCA cycle oxidizes imported organic carbon and supplies biosynthetic
      precursors.
    evidence:
    - reference: DOI:10.3389/fmicb.2024.1441865
      notes: Genomes encode complete glycolysis, gluconeogenesis and TCA cycle enzymes
        oxidizing imported organic carbon for precursor generation.
    predicate_id: METPO:2000202
  - subject: glyoxylate_cycle
    predicate: enhances
    object: biomass
    description: Routing acetyl-CoA through the glyoxylate shunt bypasses CO2-releasing
      TCA steps, enhancing carbon-to-biomass conversion.
    evidence:
    - reference: DOI:10.1111/raq.12700
      notes: The glyoxylate shunt bypasses CO2-releasing TCA steps, enhancing conversion
        of carbon into biomass.
  - subject: catabolism
    predicate: couples to
    object: aerobic_respiration
    description: Oxidation of imported organic substrates couples to aerobic respiration
      for energy conservation.
    evidence:
    - reference: DOI:10.3389/fmicb.2024.1441865
      notes: Sugars are used as electron donors for aerobic respiration; respiration
        is the energy-conservation module for heterotrophy.
  - subject: catabolism
    predicate: couples to
    object: fermentation
    description: Under anaerobic conditions heterotrophic energy conservation proceeds
      via fermentation and substrate-level phosphorylation.
    evidence:
    - reference: DOI:10.1016/j.chom.2024.05.011
      notes: Anaerobic conditions favor substrate-level phosphorylation (fermentation)
        for heterotrophic energy conservation.
curation_history:
- timestamp: '2026-05-05T01:35:46.873704+00:00'
  curator: seed_from_metpo
  action: SEEDED_FROM_METPO
  changes: imported from data/raw/metpo.owl (CLASS)
  llm_assisted: false
- timestamp: '2026-05-09T00:00:00-07:00'
  curator: codex
  action: ADDED_CAUSAL_GRAPH
  changes: Added DOI-backed causal graph for organic carbon uptake, catabolism, precursor
    metabolites, anabolism, and biomass formation.
  llm_assisted: true
- timestamp: '2026-05-16T05:00:00-07:00'
  curator: claude
  action: ADDED_ORGANISM_EXAMPLE
  changes: Added Escherichia coli K-12 organism example with PMID-backed evidence.
  llm_assisted: true
- timestamp: '2026-05-20T03:35:31Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 3 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2000202×2, METPO:2000006×1).
  llm_assisted: true
- timestamp: '2026-05-24T04:41:04Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (METPO:1007501×1).
  llm_assisted: true
- timestamp: '2026-05-24T07:34:58Z'
  curator: claude
  action: RETYPE_CAUSAL_NODES
  changes: 'Re-typed 1 causal-node node_type field(s) to align with CausalNodeTypeEnum
    semantics: biomass: BIOLOGICAL_PROCESS → CHEMICAL ×1.'
  llm_assisted: true
- timestamp: '2026-06-14T05:51:47Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (CHEBI:72695×1).
  llm_assisted: true
- timestamp: '2026-06-17T04:09:45Z'
  curator: claude
  action: REMOVE_REDUNDANT_SYNONYM
  changes: Removed 1 synonym(s) whose text duplicated the label (seeder redundancy;
    no information lost).
  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: '2026-06-24T17:21:14Z'
  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: '2026-06-24T17:21:20Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 2 causal-node grounding field(s) via mappings/node_grounding.tsv
    (GO:0009060×1, GO:0006113×1).
  llm_assisted: true
- timestamp: '2026-06-24T17:23:34Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 3 causal-node grounding field(s) via mappings/node_grounding.tsv
    (GO:0009058×1, GO:0006099×1, GO:0006097×1).
  llm_assisted: true