outer endospore membrane

GO:0043594 · Spore · Membrane · Proposed

The outer membrane around a bacterial endospore, located between the endospore cortex and the endospore coat. [GO:0043594]

Synonyms: spore outer membrane; cortex membrane

Part of: endospore external encapsulating structure (GO:0043591)

Xrefs: uniprot.location:SL-0365 — Spore outer membrane

Components

Component	Type	Part of / acts on	Grounding	Genes	Stoichiometry	Essential	Role
outer endospore membrane lipid bilayer	Lipid	part of	Reviewed label only (reviewed name; no accession asserted)			UNKNOWN	Mature-spore membrane layer positioned outside the endospore cortex and inside the inner spore coat. `GO:0043594` GO:0043594 defines the outer endospore membrane as the membrane around a bacterial endospore between cortex and coat. `uniprot.location:SL-0365` — Spore outer membrane UniProt SL-0365 describes the spore outer membrane, or cortex membrane, as a mature-spore membrane between the cortex and the inner layer of the coat.

NCBITaxon:1239 Bacillota — COMMON: Outer endospore membranes occur in endospore-forming Bacillota lineages as part of the mature spore envelope, but are absent from non-sporulating members of the phylum. [DOI:10.1038/nrmicro2921]

NCBITaxon:1423 Bacillus subtilis — Classical bacterial endospore model with cortex and coat layers that flank the mature outer endospore membrane. [DOI:10.1038/nrmicro2921]

The outer endospore membrane is a mature-spore membrane layer positioned between the endospore cortex and the inner layer of the endospore coat.

Subject	Predicate	Object	Evidence
outer endospore membrane	is part of	endospore external encapsulating structure	`GO:0043594` GO:0043594 places the membrane around a bacterial endospore. `GO:0043591` GO:0043591 identifies the containing external encapsulating structure.
outer endospore membrane	lies outside	endospore cortex	`GO:0043594` GO:0043594 defines the outer endospore membrane by its position between cortex and coat. `uniprot.location:SL-0365` — Spore outer membrane UniProt SL-0365 calls the same location the spore outer membrane or cortex membrane.
endospore coat	surrounds	outer endospore membrane	`GO:0043594` GO:0043594 positions the outer endospore membrane between the cortex and coat.

INTERPRETATION (RESOLVED): Keep the outer endospore membrane at mature-spore scope. GO:0043594 denotes the outer membrane around a bacterial endospore, and UniProt SL-0365 scopes the equivalent Spore outer membrane to the cortex membrane of bacterial mature spores between the cortex and inner coat.
CURATION_TODO (OPEN): Find an exact source-neutral grounding for outer endospore membrane lipids. The membrane is groundable as a GO cellular component, but no exact generic lipid, CHEBI, GO, or membrane-composition term for its mature-spore bilayer was curated.

GO:0043594 Gene Ontology cellular-component term for the outer endospore membrane.
GO:0016020 Gene Ontology cellular-component term for membrane parentage.
GO:0043591 Gene Ontology cellular-component term for the containing endospore external encapsulating structure.
GO:0043593 Gene Ontology cellular-component term for the adjacent endospore coat.
GO:0043595 Gene Ontology cellular-component term for the adjacent endospore cortex.
uniprot.location:SL-0365 — Spore outer membrane UniProt Subcellular Location SL-0365 maps Spore outer membrane to GO:0043594 and lists cortex membrane as an exact name.
DOI:10.1038/nrmicro2921 McKenney, Driks and Eichenberger 2012, The Bacillus subtilis endospore: assembly and functions of the multilayered coat, Nature Reviews Microbiology.

2026-09-13T00:59:15Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-13T01:00:13Z codex · EXPANDED_RECORD — Added the UniProt SL xref and exact synonyms, membrane parentage, endospore external-structure parthood, a mature-spore lipid-bilayer component, Bacillota distribution, a Bacillus subtilis example, GO and literature evidence, a nonmechanistic topology graph, and boundary/grounding discussions.
2026-09-13T01:07:55Z codex · ADDRESS_REVIEW — Resolved #729 by changing the cortex topology edge predicate from separates to lies outside.
2026-09-13T01:10:05Z codex · ADDRESS_REVIEW — Resolved #728 by narrowing the outer endospore membrane boundary discussion to the mature-spore scope supported by GO:0043594 and UniProt SL-0365.