identifier: METPO:1000657
label: photoheterotrophic
definition: A trophic type in which an organism uses light as the energy source and
  organic compounds as the primary carbon source for biosynthesis.
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: photoheterotroph
  synonym_type: RELATED_SYNONYM
  source: metpo.owl
- synonym_text: photoheterotrophy
  synonym_type: RELATED_SYNONYM
  source: metpo.owl
created_by: Luke Wang
evidence:
- reference: DOI:10.1016/B978-012373944-5.00083-3
  snippet: light and reduced organic compounds
  notes: Encyclopedia chapter defines photoheterotrophy by light energy and reduced
    organic carbon.
- reference: DOI:10.1128/AEM.01747-12
  snippet: accumulated 25% to 110% more biomass
  notes: Experimental AAP study supports light-enhanced assimilation of supplied organic
    carbon.
canonical_examples:
- taxon_id: NCBITaxon:1076
  taxon_label: Rhodopseudomonas palustris
  note: "metabolically versatile photoheterotroph"
  reference: PMID:37556472
- taxon_id: NCBITaxon:1085
  taxon_label: Rhodospirillum rubrum
  note: "purple non-sulfur photoheterotroph"
  reference: PMID:34621257
causal_graphs:
- graph_id: photoheterotrophic_light_organic_carbon
  title: Photoheterotrophic light-supported organic carbon assimilation
  description: DOI-backed graph linking light capture, bacteriochlorophyll reaction
    centers, photosynthetic electron transport, ATP generation, and organic carbon
    assimilation.
  nodes:
  - node_id: photoheterotrophic_trait
    label: photoheterotrophic
    node_type: TRAIT
    grounding: METPO:1000657
    description: Trophic type using light energy and organic carbon for biosynthesis.
  - node_id: light
    label: light
    node_type: ENVIRONMENTAL_FACTOR
    description: Energy input harvested by photoheterotrophs.
    grounding: PATO:0001717
  - node_id: bacteriochlorophyll
    label: bacteriochlorophyll
    node_type: CHEMICAL
    description: Light-harvesting pigment in many anoxygenic photoheterotrophs.
    grounding: CHEBI:38201
  - node_id: photosynthetic_reaction_center
    label: photosynthetic reaction center
    node_type: GENE_OR_PROTEIN
    description: Pigment-protein complex initiating photochemical charge separation.
  - node_id: photosynthetic_electron_transport
    label: photosynthetic electron transport
    node_type: PATHWAY
    description: Light-induced electron-transfer pathway supporting energy conservation.
    grounding: GO:0009767
  - node_id: atp
    label: ATP
    node_type: CHEMICAL
    grounding: CHEBI:30616
    description: Energy carrier generated by photosynthetic electron transport.
  - node_id: organic_carbon
    label: organic carbon
    node_type: CHEMICAL
    description: Reduced organic compound used as the primary carbon source.
    grounding: CHEBI:50860
  - node_id: biomass
    label: biomass
    node_type: CHEMICAL
    description: Cell material produced from assimilated organic carbon.
    grounding: METPO:1007501
  - node_id: proteorhodopsin_proton_pumping
    label: proteorhodopsin proton pumping
    node_type: BIOLOGICAL_PROCESS
    description: Light-driven proton translocation by proteorhodopsin in rhodopsin-based
      photoheterotrophs.
  - node_id: membrane_potential
    label: membrane potential
    node_type: STATE
    description: Transmembrane electrochemical proton-motive force generated by light-driven
      ion pumping.
  - node_id: atp_production
    label: ATP production
    node_type: BIOLOGICAL_PROCESS
    description: Synthesis of ATP driven by the proton-motive force.
  - node_id: proteorhodopsin
    label: proteorhodopsin
    node_type: GENE_OR_PROTEIN
    description: Retinal-binding light-driven proton pump enabling rhodopsin-based
      phototrophy.
    grounding: UniProtKB:A0A1D7QWW9
  - node_id: nadph_anabolic
    label: NAD(P)H for anabolic metabolism
    node_type: CHEMICAL
    description: Reducing equivalents required for biosynthesis; not generated by
      proteorhodopsin phototrophy.
  - node_id: photophosphorylation
    label: photophosphorylation
    node_type: BIOLOGICAL_PROCESS
    description: Light-driven ATP synthesis used by aerobic anoxygenic phototrophs.
  - node_id: aerobic_anoxygenic_phototrophs
    label: aerobic anoxygenic phototrophs
    node_type: TRAIT
    description: Facultative photoheterotrophs harvesting light to generate ATP while
      relying on organic matter.
  - node_id: dissolved_organic_matter
    label: dissolved organic matter
    node_type: CHEMICAL
    description: Organic carbon/energy source on which aerobic anoxygenic phototrophs
      primarily rely.
  edges:
  - subject: photoheterotrophic_trait
    predicate: uses energy source
    object: light
    description: Photoheterotrophic growth uses light as the energy input.
    evidence:
    - reference: DOI:10.1016/B978-012373944-5.00083-3
      snippet: light and reduced organic compounds
      notes: Supports light as the energy source in photoheterotrophy.
    predicate_id: METPO:2000010
  - subject: bacteriochlorophyll
    predicate: part of
    object: photosynthetic_reaction_center
    description: Bacteriochlorophyll pigments occur in reaction centers of many anoxygenic
      phototrophs.
    evidence:
    - reference: DOI:10.1128/AEM.01747-12
      snippet: reaction centers composed of bacteriochlorophyll
      notes: Supports BChl-containing reaction centers in aerobic anoxygenic phototrophs.
    predicate_id: biolink:part_of
  - subject: light
    predicate: captured by
    object: photosynthetic_reaction_center
    description: Reaction centers capture light to initiate photochemical energy conversion.
    evidence:
    - reference: DOI:10.1016/B978-0-12-809633-8.20672-9
      snippet: utilize light as an energy source
      notes: Supports reaction-center-based light utilization by chlorophototrophs.
  - subject: photosynthetic_reaction_center
    predicate: initiates
    object: photosynthetic_electron_transport
    description: Photochemical charge separation drives photosynthetic electron transport.
    evidence:
    - reference: DOI:10.1016/B978-0-12-809633-8.20672-9
      snippet: light-induced redox chemistry
      notes: Supports reaction-center photochemistry leading to electron transfer.
  - subject: photosynthetic_electron_transport
    predicate: produces
    object: atp
    description: Photosynthetic electron transport conserves light energy as ATP.
    evidence:
    - reference: DOI:10.1016/B978-0-12-809633-8.20672-9
      snippet: can be used to produce ATP
      notes: Supports ATP production downstream of phototrophic electron transfer.
    predicate_id: METPO:2000202
  - subject: photoheterotrophic_trait
    predicate: uses carbon source
    object: organic_carbon
    description: Photoheterotrophs require organic compounds as the carbon source.
    evidence:
    - reference: DOI:10.1016/B978-012373944-5.00083-3
      snippet: reduced organic compounds
      notes: Supports reduced organic compounds as the carbon source in photoheterotrophy.
    predicate_id: METPO:2000006
  - subject: organic_carbon
    predicate: assimilated into
    object: biomass
    description: Light-supported photoheterotrophs assimilate supplied organic carbon
      into biomass.
    evidence:
    - reference: DOI:10.1128/AEM.01747-12
      snippet: accumulate the supplied organic carbon
      notes: Supports organic carbon assimilation into biomass under light.
  - subject: light
    predicate: activates
    object: proteorhodopsin_proton_pumping
    description: Light drives proton pumping by proteorhodopsin in rhodopsin-based
      photoheterotrophs.
    evidence:
    - reference: DOI:10.1007/s12275-024-00125-0
      notes: the light-driven proton pumping by PR
    predicate_id: RO:0002213
  - subject: proteorhodopsin_proton_pumping
    predicate: generates
    object: membrane_potential
    description: Proteorhodopsin proton transport establishes a membrane potential.
    evidence:
    - reference: DOI:10.1007/s12275-024-00125-0
      notes: PR-mediated proton transport could generate a sufficient membrane potential
        for ATP production
    predicate_id: biolink:produces
  - subject: membrane_potential
    predicate: enables
    object: atp_production
    description: The membrane potential drives ATP production.
    evidence:
    - reference: DOI:10.1007/s12275-024-00125-0
      notes: generate a sufficient membrane potential for ATP production
    predicate_id: RO:0002327
  - subject: proteorhodopsin
    predicate: cannot generate
    object: nadph_anabolic
    description: 'Boundary edge: proteorhodopsin phototrophy yields ATP but no reducing
      power for biosynthesis.'
    evidence:
    - reference: DOI:10.4014/jmb.2410.10034
      notes: PR can never be harnessed to generate NAD(P)H for anabolic metabolism
  - subject: aerobic_anoxygenic_phototrophs
    predicate: perform
    object: photophosphorylation
    description: Aerobic anoxygenic phototrophs generate ATP via photophosphorylation.
    evidence:
    - reference: DOI:10.1186/s40793-024-00573-6
      notes: AAPs are facultative photoheterotrophs that harvest light energy and
        generate ATP by photophosphorylation
  - subject: photophosphorylation
    predicate: produces
    object: atp
    description: Photophosphorylation conserves light energy as ATP.
    evidence:
    - reference: DOI:10.1186/s40793-024-00573-6
      notes: generate ATP by photophosphorylation using a unique type of bacteriochlorophyll-a-containing
        reaction center
    predicate_id: METPO:2000202
  - subject: aerobic_anoxygenic_phototrophs
    predicate: relies primarily on
    object: dissolved_organic_matter
    description: Aerobic anoxygenic phototrophs primarily rely on dissolved organic
      matter as their energy/carbon source.
    evidence:
    - reference: DOI:10.1186/s40793-024-00573-6
      notes: they primarily rely on dissolved organic matter as an energy source
curation_history:
- timestamp: '2026-05-05T01:35:46.880718+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 light capture, bacteriochlorophyll reaction
    centers, ATP generation, and organic carbon assimilation.
  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:2000010×1, METPO:2000202×1, METPO:2000006×1).
  llm_assisted: true
- timestamp: '2026-05-20T05:49:25Z'
  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: '2026-05-24T04:38:01Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 3 causal-node grounding field(s) via mappings/node_grounding.tsv
    (PATO:0001717×1, GO:0009767×1, CHEBI:50860×1).
  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: '2026-05-24T07:34:59Z'
  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:38201×1).
  llm_assisted: true
- timestamp: '2026-06-23T00:00:00Z'
  curator: claude
  action: ENRICH_CAUSAL_GRAPH
  changes: Added 7 evidence-backed generic edges (8 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:15Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 4 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002213×1, biolink:produces×1, RO:0002327×1, METPO:2000202×1).
  llm_assisted: true
- timestamp: '2026-06-24T17:21:20Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (UniProtKB:A0A1D7QWW9×1).
  llm_assisted: true