identifier: traitmech:000649 label: extracellular membrane vesicle production definition: A physiological phenotype in which microbial cells give rise to closed, cell-derived lipid-membrane vesicles in the extracellular space. definition_source: DOI:10.1038/ncomms11220 trait_category: PHYSIOLOGY term_kind: CLASS mapping_status: PROPOSED parent_traits: - METPO:1000059 canonical_examples: - taxon_id: NCBITaxon:420247 taxon_label: Methanobrevibacter smithii ATCC 35061 reference: DOI:10.1038/s41467-025-60272-9 note: Type strain PS (= ATCC 35061 = DSM 861). Vesicles were purified from exponentially growing cultures at 37 C in modified DSM 119 medium under H2/CO2 and examined by TEM. The collection record https://www.dsmz.de/collection/catalogue/details/culture/DSM-861 traces PS to a primary sewage digester in Gainesville, not to a human donor; it supplies provenance, not independent vesicle evidence. NCBI Taxonomy resolves this strain to species 2173. This is a culture observation, not direct in-gut vesicle production. evidence: - reference: DOI:10.1038/ncomms11220 snippet: Super-resolution microscopy reveals that explosive cell lysis also produces shattered membrane fragments that rapidly form MVs. notes: PMID:27075392, PMC4834629. Scientific Abstract, not the editorial teaser, directly read in Europe PMC XML; selected Results and strain/isolation Methods also read. Live super-resolution imaging in Pseudomonas aeruginosa distinguishes vesicles from fragments and supports membrane reassembly after lysis. Lys dependence in biofilms/stress does not extend to ordinary oxic planktonic cultures, where the lys mutant retains comparable MV levels. Reporter/deletion/rescue experiments are qualified observations, not proof of one universal route. Actual panels and supplements were not visually inspected. - reference: DOI:10.1038/s41467-017-00492-w snippet: Through these openings, cytoplasmic membrane material protrudes into the extracellular space and is released as MVs. notes: PMID:28883390, PMC5589764. Scientific Abstract, separate from the appended teaser, and selected Results/Methods directly read in Europe PMC XML. The openings are endolysin-associated peptidoglycan holes in Bacillus subtilis. Live imaging and induced strains support extrusion from cells that ultimately die; tomography uses an engineered skinny ponA deletion, not wild-type cells. Static tomographic stages are not a measured time sequence. This route differs from explosive-fragment reassembly. This study and the 2016 paper share investigators; they are not independent-laboratory replications. Actual panels were not visually inspected. - reference: DOI:10.1371/journal.pone.0011113 snippet: Bilayered vesicles with diameters at the 100–300 nm range were found in extracellular fractions from yeast cultures. notes: PMID:20559436, PMC2885426. Scientific Abstract and Methods s2a-s2c, Results s3a/s3d directly read in Europe PMC XML. Saccharomyces cerevisiae WT and trafficking mutants yield vesicles after supernatant fractionation and TEM. Heat-killed controls yielded no vesicle-like structures; viability controls were reported without displayed data. SEC/MVB perturbations alter composition and sterol-based release proxies without abolishing production. The abstract's concluding requirement language is not taken as a universal necessity claim. Size is assay-specific; WT denotes laboratory comparators, not verified natural isolates. Actual panels were not visually inspected. - reference: DOI:10.1038/s41467-025-60272-9 snippet: The EVs were isolated from exponentially growing M. smithii cultures to limit the contamination of the EV preparations with cell debris. notes: PMID:40461479, PMC12134362. Full-text Results Sec3 quote, not an abstract quote, checked in Europe PMC XML. Sec3/Sec7 and Methods Sec10-Sec12 describe PS cultures, density-gradient purification, TEM and particle assays. Instrument detection limits yield different size distributions. Cryo-ET suggests budding and wall passage; the large-vesicle lysis route is hypothesized, not directly demonstrated. DNA/protein cargo annotations do not demonstrate increased methane production. Actual panels and supplements were not visually inspected. discussions: - discussion_id: extracellular-vesicle-production-scope-and-mapping prompt: Separate vesicle production from particle identity and cargo effects. kind: CURATION_TODO status: OPEN rationale: Include vesicles produced by non-lytic release or membrane reassembly after cell lysis; the producer need not survive. Require evidence for intact extracellular vesicles, not bulk membrane-dye signal, unclosed debris, intracellular organelles, whole daughter cells or virions. Vesicle-associated viral DNA alone does not make a particle a virion. Gas vesicles are proteinaceous intracellular inclusions. Exocytosis traitmech:000637 describes fusion-pore discharge, which need not release an intact vesicle. The yeast source attributes roles to both conventional and unconventional trafficking, so unconventional protein secretion traitmech:000648 is not a universal parent; possible overlap is not disjointness. Outer-membrane vesicles and exosomes are narrower or route-specific usages, not exact synonyms. No universal size, cargo, lipid-bilayer architecture or ecological function is imposed. Retain phenotype METPO:1000059 pending human hierarchy and external mapping review; no exact xref is asserted. posed_by: codex posed_date: '2026-10-06' - discussion_id: extracellular-vesicle-production-route-mechanisms prompt: Ground separate biogenesis mechanisms without universalizing them. kind: KNOWLEDGE_GAP status: OPEN rationale: The bacterial sources support distinct endolysin-associated routes; the yeast work supports trafficking contributions; the methanogen's budding and large-vesicle lysis models remain qualified. No common protein apparatus follows from these observations. Before adding route-specific causal graphs, inspect the remaining panels, supplements and strain provenance and resolve the relevant protein accessions with taxon-paired functional evidence. The verified PS exemplar does not ground bacterial Lys or yeast SEC proteins. Do not infer vesicle production from a sequence feature, cargo annotation, membrane blebbing alone or an isolation protocol that mechanically manufactures particles from cells. posed_by: codex posed_date: '2026-10-06' curation_history: - timestamp: '2026-10-06T19:52:36Z' curator: codex action: MINTED_TRAITMECH_ID changes: Added extracellular membrane vesicle production with four DOI-backed snippets and a provenance-qualified M. smithii PS example. Ignored-and-hidden duplicate searches and the pinned METPO audit found no exact record. Reserved METPO:1060200 in v525. Retained route, particle-identity and mapping limits; existing records are unchanged. llm_assisted: true