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organoheterotrophic

METPO:1000664 · CLASS · REVIEWED

A trophic type characterized by the use of organic compounds as both electron donors and primary carbon sources for energy generation and biosynthesis.

Organoheterotrophic organic donor and carbon use

DOI-backed graph linking organic compounds as electron donors and carbon sources to central metabolism, respiratory energy conservation, ATP, and biomass.

Organoheterotrophic organic donor and carbon use Interactive directed graph showing evidence-backed causal relationships for organoheterotrophic.

Edge evidence

  • organoheterotrophic has electron donor organic compound METPO:2007701

    Organic compounds serve as the electron donors for organoheterotrophy.

    • DOI:10.1021/acsomega.3c02205 organic molecules ... electron source Supports organic molecules as electron sources in organoheterotrophic categories.
  • organoheterotrophic has carbon source organic compound METPO:2007806

    Heterotrophy uses organic compounds as carbon sources.

    • DOI:10.1016/B978-012373944-5.00083-3 organic compounds as the primary sources of carbon Supports organic compounds as the carbon source for heterotrophic growth.
  • organic compound metabolized by central carbon metabolism

    Organic compounds enter central metabolism for catabolism and biosynthesis.

    • DOI:10.1016/B978-012373944-5.00083-3 catabolism Supports breakdown of nutrients to provide energy and biosynthetic precursors.
  • central carbon metabolism feeds electrons into respiratory chain METPO:2007402

    Oxidation of organic substrates supplies reducing equivalents to respiratory chains.

    • DOI:10.1016/j.bbabio.2008.09.008 electron transfer process Supports respiratory energy conservation through electron transfer.
  • central carbon metabolism oxidizes carbon to carbon dioxide

    Organic substrate oxidation can release CO2.

    • DOI:10.1016/B978-012373944-5.00083-3 dissimilation Supports oxidation of nutrients to provide energy for biosynthesis and maintenance.
  • respiratory chain has output ATP RO:0002234

    Respiratory electron transfer conserves energy as ATP.

    • DOI:10.1016/j.bbabio.2008.09.008 drives ATP synthesis Supports ATP synthesis from respiratory energy conservation.
  • organic compound assimilated into biomass

    Organic carbon supplies building blocks for biomass.

    • DOI:10.1016/B978-012373944-5.00083-3 incorporation of a compound into biomass Supports assimilation of organic nutrients into new cell material.
  • glycolysis (Embden-Meyerhof pathway) enables central carbon metabolism RO:0002327

    A complete glycolytic (Embden-Meyerhof) pathway enables catabolism of organic carbon substrates.

    • DOI:10.1128/spectrum.04110-22 Genome annotation identifies a complete glycolysis (Embden-Meyerhof) pathway; standard route for organic carbon catabolism.
  • tricarboxylic acid cycle enables central carbon metabolism RO:0002327

    A complete TCA cycle enables oxidative catabolism of organic substrates within central metabolism.

    • DOI:10.1128/spectrum.04110-22 A complete tricarboxylic acid (TCA) cycle is present, indicating capacity for oxidative catabolism of organic substrates.
  • NADH dehydrogenase (complex I) contributes to oxidative phosphorylation RO:0002326

    NADH dehydrogenase (complex I) feeds electrons into the respiratory chain for oxidative phosphorylation.

    • DOI:10.1128/spectrum.04110-22 A complete oxidative phosphorylation pathway is encoded, including NADH dehydrogenase (nuoABCDEFGHIJKLMN).
  • cytochrome bc1 complex (complex III) contributes to oxidative phosphorylation RO:0002326

    The cytochrome bc1 complex transfers electrons in the respiratory chain supporting oxidative phosphorylation.

    • DOI:10.1128/spectrum.04110-22 A complete oxidative phosphorylation pathway is encoded, including cytochrome bc1 (petABC).
  • oxidative phosphorylation has output ATP RO:0002234

    Oxidative phosphorylation conserves respiratory energy as ATP.

    • DOI:10.1128/spectrum.04110-22 A complete oxidative phosphorylation pathway is encoded, coupling electron transfer to ATP synthesis.

Provenance

Source
METPO (2025-11-25)
Author
Anthea Guo
Definition source
DOI:10.1016/B978-012373944-5.00083-3

Parent traits (1)

Synonyms (1)

  • organoheterotroph RELATED_SYNONYM · metpo.owl

kg-microbe context

Matched 1 kg-microbe node via direct_metpo.

  • METPO:1000664 [-0.481, -1.211, -3.077, -0.947, …]

512-dim DeepWalkSkipGramEnsmallen embedding from kg-microbe (2026-04-25).

Nearest neighbors in embedding space

Top-8 cosine-similar METPO traits from the 2026-04-25 deepwalk (512-D).

Deep research

Generated by just research-trait; source: research/traits/physiology/organoheterotrophic-deep-research-falcon.md

Unreviewed literature output — not curated TraitMech content Ontology identifiers suggested below have not been resolved against their ontologies, and some are known to be wrong. Check any CURIE against the source before using it. 
# Curation report: organoheterotrophic microbial trait

## 1. Scope summary

**Trait:** organoheterotrophic  
**Identifier:** `METPO:1000664`  
**Category/kind/status:** PHYSIOLOGY / CLASS / REVIEWED  
**Parent:** `METPO:1000631`

Organoheterotrophy is a trophic strategy in which **organic compounds provide both the principal carbon source and the reducing equivalents/electrons used for energy conservation**. A concise operational formulation is: uptake or extracellular depolymerization of organic matter, intracellular catabolism through one or more central-carbon routes, allocation of carbon skeletons to biomass, and conservation of energy by respiration or fermentation. A major review defines heterotrophs as organisms that “respire organic compounds to gain energy and build up biomass”; oxidation may use oxygen or alternative electron acceptors such as nitrate, ferric iron, or sulfate (braun2021reviewsandsyntheses pages 1-2).

The trait is broader than aerobic growth. It includes aerobic and anaerobic respiration and fermentative growth, provided organic compounds remain the primary carbon source and electron donors. Conversely, presence of glycolysis, a TCA cycle, transporters, or respiratory genes alone is insufficient to establish the phenotype.

### Boundary cases

- **Autotrophy:** inorganic carbon is the principal carbon source. Mere anaplerotic incorporation of CO2 does not make an organism autotrophic: heterotrophic anaplerosis commonly contributes approximately 1–8% of microbial biomass carbon (braun2021reviewsandsyntheses pages 2-4, braun2021reviewsandsyntheses pages 1-2).
- **Mixotrophy:** simultaneous or condition-dependent combination of heterotrophic machinery with phototrophy or chemolithotrophy. Therefore, demonstrated organoheterotrophic growth may be one mode of a mixotroph rather than an organism-wide obligate phenotype (eiler2006evidenceforthe pages 1-2, burgsdorf2021rethinkingsymbioticmetabolism pages 1-4).
- **Lithoheterotrophy:** organic carbon remains the biomass source, but inorganic compounds provide some or all reducing power. It should not be asserted as organoheterotrophy unless organic compounds are also shown to act as electron donors (burgsdorf2021rethinkingsymbioticmetabolism pages 1-4).
- **Photoheterotrophy:** organic carbon is assimilated, but light supplies energy. This is heterotrophic with respect to carbon but is not necessarily organoheterotrophic under the supplied definition because organic compounds need not be the primary energy/electron source.
- **Methylotrophy and methanotrophy:** organic C1 compounds can satisfy the literal organic-donor/organic-carbon criterion, but many databases treat these as separate specialist trophic classes. Methanotrophs may derive up to 50% of biomass carbon from CO2 while still depending on methane-derived energy; any mapping should follow METPO’s explicit modeling policy (braun2021reviewsandsyntheses pages 1-2, braun2021reviewsandsyntheses pages 4-5).
- **Assay interpretation:** growth on an organic substrate is strong phenotype evidence; disappearance of substrate plus biomass labeling is stronger. Genome or transcript detection only establishes potential or activity of modules, not necessarily organic carbon as both primary carbon and energy source (burgsdorf2021rethinkingsymbioticmetabolism pages 1-4, campana2021dna‐stableisotopeprobing pages 1-2).

## 2. Candidate nodes grouped by type

### Trait and process nodes

- organoheterotrophic — `METPO:1000664`
- organic-compound uptake — label-only candidate
- extracellular organic-matter depolymerization — label-only candidate
- heterotrophic carbon metabolism — label-only candidate
- glycolysis / Embden–Meyerhof–Parnas pathway — `KEGG:map00010`
- Entner–Doudoroff pathway — label-only pending ontology validation
- pentose-phosphate pathway — `KEGG:map00030`
- tricarboxylic-acid cycle — `KEGG:map00020`
- respiratory electron transport — `GO:0022900`
- ATP synthesis coupled to proton transport — `GO:0015986`
- fermentation — `GO:0006113`
- biosynthesis/anabolism — `GO:0009058`
- anaplerotic CO2 fixation — label-only candidate
- microbial carbon-use efficiency — label-only experimental-factor node

### Chemicals and nutrients

- organic compound — `CHEBI:33229`
- dissolved organic matter and particulate organic matter — label-only; these are mixtures rather than single ChEBI entities
- glucose — use a verified ChEBI mapping during implementation
- pyruvate — `CHEBI:15361`
- acetyl-CoA — `CHEBI:15351`
- NADH — `CHEBI:16908`
- NADPH — `CHEBI:16474`
- oxygen — `CHEBI:15379`
- carbon dioxide — `CHEBI:16526`
- acetate — `CHEBI:30089`
- ethanol — `CHEBI:16236`
- nitrate, ferric iron, and sulfate — verify ChEBI CURIEs before YAML insertion
- ATP, ADP, proton, quinone/quinol, lactate, and TCA intermediates — retain as label-only until identifier validation

### Proteins, enzymes, transporters, and complexes

These should be modeled as **representative or optional modules**, not universally required markers:

Showing the first 60 of 247 lines of findings; the linked file also carries the run's front matter and the prompt it was given — read the full report.

Curation history

  1. · SEEDED_FROM_METPO · seed_from_metpo

    imported from data/raw/metpo.owl (CLASS)

  2. · ADDED_CAUSAL_GRAPH · codex

    Added DOI-backed causal graph for organic compounds as electron donors and carbon sources supporting respiration, ATP, and biomass.

  3. · GROUND_CAUSAL_PREDICATES · claude

    Grounded 3 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (METPO:2000009×1, METPO:2000006×1, METPO:2000202×1).

  4. · GROUND_CAUSAL_PREDICATES · claude

    Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (METPO:2007402×1).

  5. · GROUND_CAUSAL_NODES · claude

    Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (GO:0022904×1).

  6. · GROUND_CAUSAL_NODES · claude

    Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (METPO:1007501×1).

  7. · RETYPE_CAUSAL_NODES · claude

    Re-typed 1 causal-node node_type field(s) to align with CausalNodeTypeEnum semantics: biomass: BIOLOGICAL_PROCESS → CHEMICAL ×1.

  8. · GROUND_CAUSAL_NODES · claude

    Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (CHEBI:50860×1).

  9. · ENRICH_CAUSAL_GRAPH · claude

    Added 5 evidence-backed generic edges (5 new nodes) from the deep-research report.

  10. · GROUND_CAUSAL_PREDICATES · claude

    Grounded 5 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002327×2, RO:0002326×2, METPO:2000202×1).

  11. · GROUND_CAUSAL_NODES · claude

    Grounded 2 causal-node grounding field(s) via mappings/node_grounding.tsv (GO:0006099×1, GO:0006119×1).

  12. · REVERSE_CAUSAL_EDGE_DIRECTION · claude

    Reversed 1 causal edge from <trait> uses electron donor <chemical> to <chemical> enables <trait> (predicate_id METPO:2000009 -> RO:0002327), issue 295. METPO:2000009 is rdfs:subPropertyOf METPO:2000001, whose rdfs:domain is METPO:1000525 (microbe), so the trait-subject form entailed that this TRAIT node is a microbe; CausalNodeTypeEnum has no organism member, so no causal-graph edge can satisfy that domain. Evidence unchanged; only subject/predicate/object/predicate_id and the edge description moved. Note RO:0002327 has range 'biological process or activity', so the new form is not fully range-correct either - tracked in issue 302.

  13. · MIGRATE_ENABLES_TRAIT_EDGES · claude

    Migrated 1 causal edge(s) off enables/RO:0002327 with a TRAIT object (1 to has electron donor), issue 302. RO:0002327 has range 'biological process or activity', which a trait (a disposition) cannot satisfy, so the previous form entailed trait is-a BiologicalProcessOrActivity. The replacements are proposed in proposals/metpo_traitmech_v8 and are placeholder ids until METPO mints them. 1 electron edge(s) were also reversed back to trait -> chemical, restoring the donor/acceptor role that PR 300 collapsed onto enables (issue 303); the organism-subject problem that forced that collapse does not arise here because these predicates take a causal-node domain rather than METPO:2000001's microbe domain (issue 301).

  14. · MIGRATE_MICROBE_DOMAIN_EDGES · claude

    Re-grounded 3 causal edge(s) off microbe-domain METPO predicates (1 to has carbon source, 2 to has output), issue 301. The previous predicates are transitively rdfs:subPropertyOf METPO:2000001, whose rdfs:domain is METPO:1000525 (microbe), so a causal-graph subject entailed that the subject IS a microbe; CausalNodeTypeEnum has no organism member, so no such edge could ever satisfy the domain. Edge directions are unchanged - this pass only relabels and re-grounds. RO:0002234 (has output) is used where the subject is an activity, since biolink gives it the domain 'biological process or activity'; the METPO replacements are proposed in proposals/metpo_traitmech_v8 and v9 and are placeholder ids until METPO mints them.

  15. · NORMALISE_NODE_TYPE · claude

    Under the PATHWAY-vs-BIOLOGICAL_PROCESS rule, one node_id means one thing corpus-wide (issue 356): oxidative_phosphorylation is typed PATHWAY. PATHWAY is a named, conventionally enumerable multi-step route; BIOLOGICAL_PROCESS is everything else. A named route through enumerable complexes -- environment/ph_delta_mid1.yaml lists them (nuo, cyo, ndh, sdh). The rule breaks what was a 2-2 tie before this tranche.