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.

Trait evidence (2)

DOI:10.1016/B978-012373944-5.00083-3
organic compounds as the primary sources of carbon and energy

Encyclopedia chapter supports organic compounds as carbon and energy sources in heterotrophy.
DOI:10.1016/j.bbabio.2008.09.008
free energy of a redox reaction

Review supports energy conservation from electron donor oxidation through respiratory chains.

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.

MECHANISTIC · This graph models the respiratory branch of organoheterotrophy. The E. coli K-12 AtpD example is one component of F-type ATP synthase and does not denote the full rotary complex or every organoheterotrophic route.

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.
ATP synthase participates in oxidative phosphorylation biolink:participates_in
F-type ATP synthase couples the respiratory gradient to ATP production.
- DOI:10.7554/eLife.21598 proton motive force drives rotation and conformational changes in the F1 catalytic sites Supports the beta-containing E. coli F1Fo ATP synthase as the ATP-producing machinery of oxidative phosphorylation.

Protein and taxon examples

Graph node Protein Taxon UniProt status Role and evidence

ATP synthase

Graph node	Protein	Taxon	UniProt status	Role and evidence
ATP synthase	`UniProtKB:P0ABB4` ATP synthase subunit beta (atpD)	Escherichia coli K-12 `NCBITaxon:83333`	`REVIEWED` retrieved 2026-08-24 · entry v155 · sequence v2	Beta component of the E. coli F1 catalytic head; this accession is not presented as the complete F1Fo complex. `DOI:10.7554/eLife.21598` proton motive force drives rotation and conformational changes in the F1 catalytic sites The primary cryo-EM study resolves the E. coli F1Fo complex and its beta-containing catalytic head; UniProt verifies the reviewed K-12 AtpD entry.

UniProtKB:P0ABB4
ATP synthase subunit beta (atpD)

Escherichia coli K-12
NCBITaxon:83333

REVIEWED
retrieved 2026-08-24 · entry v155 · sequence v2

Beta component of the E. coli F1 catalytic head; this accession is not presented as the complete F1Fo complex.

DOI:10.7554/eLife.21598 proton motive force drives rotation and conformational changes in the F1 catalytic sites The primary cryo-EM study resolves the E. coli F1Fo complex and its beta-containing catalytic head; UniProt verifies the reviewed K-12 AtpD entry.

Provenance

Identifier source: METPO (2026-06-12)
Author: Anthea Guo
Definition source: DOI:10.1016/B978-012373944-5.00083-3

Parent traits (1)

trophic type METPO:1000631

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).

physiology trophic type 0.609
physiology carboxydotrophic 0.607
physiology photolithoautotrophic 0.605
physiology hydrogenotrophic 0.604
physiology lithoheterotrophic 0.596
physiology lithoautotrophic 0.594
physiology photoorganoheterotrophic 0.585
physiology photolithotrophic 0.575

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.

Canonical examples (2)

Organisms cited as exemplars of this trait. Taxon ids are NCBITaxon and link out to the NCBI record.

Escherichia coli NCBITaxon:562 PMID:31778652 organoheterotroph
Escherichia coli K-12 NCBITaxon:83333 DOI:10.7554/eLife.21598 Strain-level organoheterotrophic model paired to the reviewed AtpD beta component of its F-type ATP synthase.

Curation history

2026-05-05T01:35:46.883809+00:00 · SEEDED_FROM_METPO · seed_from_metpo
imported from data/raw/metpo.owl (CLASS)
2026-05-08T00:00:00-07:00 · ADDED_CAUSAL_GRAPH · codex
Added DOI-backed causal graph for organic compounds as electron donors and carbon sources supporting respiration, ATP, and biomass.
2026-05-20T03:35:31Z · 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).
2026-05-23T21:30:07Z · GROUND_CAUSAL_PREDICATES · claude
Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (METPO:2007402×1).
2026-05-24T04:38:01Z · GROUND_CAUSAL_NODES · claude
Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (GO:0022904×1).
2026-05-24T04:41:04Z · GROUND_CAUSAL_NODES · claude
Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (METPO:1007501×1).
2026-05-24T07:34:59Z · RETYPE_CAUSAL_NODES · claude
Re-typed 1 causal-node node_type field(s) to align with CausalNodeTypeEnum semantics: biomass: BIOLOGICAL_PROCESS → CHEMICAL ×1.
2026-05-24T08:14:33Z · GROUND_CAUSAL_NODES · claude
Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (CHEBI:50860×1).
2026-06-23T00:00:00Z · ENRICH_CAUSAL_GRAPH · claude
Added 5 evidence-backed generic edges (5 new nodes) from the deep-research report.
2026-06-24T17:21:14Z · 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).
2026-06-24T17:23:35Z · GROUND_CAUSAL_NODES · claude
Grounded 2 causal-node grounding field(s) via mappings/node_grounding.tsv (GO:0006099×1, GO:0006119×1).
2026-08-05T12:00:00Z · 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.
2026-08-06T00:00:00Z · 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).
2026-08-06T01:00:00Z · 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.
2026-08-16T02:00:00Z · 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.
2026-08-26T03:23:00Z · CURATE_PROTEIN_TAXON_EXAMPLE · claude
Backfilled provenance (review issue 517) for the codex protein-taxon review tranche of 2026-08-24/25, which shipped without a per-record event. In this record the tranche: set graph scope organoheterotrophic_organic_donor_carbon=MECHANISTIC with scope_notes; added taxon-paired protein example(s) UniProtKB:P0ABB4 on atp_synthase (NCBITaxon:83333); regrounded 2 node(s) (nadh_dehydrogenase_complex_i: none->GO:0030964, cytochrome_bc1_complex: none->GO:0045275); added 1 node(s) and 1 edge(s) (atp_synthase); added canonical example(s) NCBITaxon:83333.