identifier: traitmech:000196
label: fumarate respiration
definition: An anaerobic respiration in which an organism uses fumarate as the terminal
  electron acceptor and reduces it to succinate for energy conservation.
definition_source: DOI:10.1128/mBio.03238-19
trait_category: METABOLISM
term_kind: CLASS
mapping_status: PROPOSED
parent_traits:
- METPO:1000802
synonyms:
- synonym_text: anaerobic respiration on fumarate
  synonym_type: RELATED_SYNONYM
  source: DOI:10.1128/JB.00389-22
evidence:
- reference: DOI:10.1128/mBio.03238-19
  snippet: under anaerobic conditions, fumarate can serve as a terminal electron acceptor,
    with fumarate reductase (FRD) transferring electrons from the reduced quinone,
    producing succinate
  notes: Ito et al. summarize Bacteroides anaerobic respiration as quinone-linked
    transfer to fumarate through fumarate reductase, producing succinate.
- reference: DOI:10.1128/JB.00389-22
  snippet: The respiratory chain responsible for anaerobic respiration (NADH to fumarate)
    involves two NADH dehydrogenases
  notes: Butler et al. describe the B. fragilis anaerobic respiratory chain as an
    NADH-to-fumarate route.
- reference: DOI:10.1128/JB.00389-22
  snippet: Analysis of fumarate reductase showed that it is synthesized and active
    under anaerobic and nanaerobic conditions
  notes: The 2023 biochemical assay shows fumarate reductase remains synthesized and
    active in B. fragilis membranes under strictly anaerobic growth and under low-oxygen
    growth.
canonical_examples:
- taxon_id: NCBITaxon:817
  taxon_label: Bacteroides fragilis
  note: Gut anaerobe with fumarate-linked anaerobic respiration characterized in membrane
    and mutant assays.
  reference: DOI:10.1128/mBio.03238-19
discussions:
- discussion_id: fumarate-respiration-xref-gap
  prompt: Resolve an exact external ontology class for organism-level fumarate respiration
    before adding a TraitRecord xref.
  kind: CURATION_TODO
  status: OPEN
  rationale: The pinned METPO snapshot contains only obsolete Fumarate respiration
    and no active organism-level class for anaerobic respiration using fumarate as
    the terminal electron acceptor. Potential GO, Rhea, EC, and protein-family terms
    for fumarate reductase or the fumarate-to-succinate reaction are narrower than
    the whole-organism anaerobic respiration phenotype and should be checked separately
    before grounding FrdABCD-level causal nodes.
  posed_by: codex
  posed_date: '2026-09-15'
curation_history:
- timestamp: '2026-09-15T00:25:53Z'
  curator: codex
  action: MINTED_TRAITMECH_ID
  changes: Minted fumarate respiration as a DOI-backed anaerobic respiration TraitRecord
    after a repository-wide duplicate review covering ignored and hidden files; the
    local METPO snapshot has only obsolete Fumarate respiration and the replacement
    placeholder is reserved in proposals/metpo_traitmech_v73.
  llm_assisted: true