TraitMech

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methyl red test positive

METPO:1005014 · CLASS · SEEDED

A phenotype in which an organism tests positive in the methyl red test, indicating mixed acid fermentation.

Trait evidence (2)

  • https://asm.org/getmedia/40946f85-9357-4563-aa8a-994427efa825/Methyl-Red-and-Voges-Proskauer-Test-Protocols.pdf
    When the culture medium turns red after addition of methyl red, because of a pH at or below 4.4 from the fermentation of glucose, the culture has a positive result for the MR test (Fig.1A).

    The ASM protocol PDF defines a positive methyl-red-test readout as red culture medium after methyl red is added, reflecting glucose fermentation that acidifies the medium to pH 4.4 or lower.

  • DOI:10.1128/JCM.42.8.3665-3669.2004
    In the ASM Manual of Clinical Microbiology, only 6 of the 18 biochemical tests used in the present investigation are listed for Klebsiella species: indole, MR, VP, LDC, ODC, and malonate

    Hansen et al. evaluated methyl red as a conventional Klebsiella biochemical test listed in the ASM Manual of Clinical Microbiology.

Provenance

Identifier source
METPO (2026-06-12)
Definition source
https://asm.org/getmedia/40946f85-9357-4563-aa8a-994427efa825/Methyl-Red-and-Voges-Proskauer-Test-Protocols.pdf

Parent traits (1)

Synonyms (1)

  • methyl red test RELATED_SYNONYM · metpo.owl

kg-microbe context

No kg-microbe node embedding matched this record in the 2026-04-25 deepwalk.

Canonical examples (1)

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

Discussions and Knowledge Gaps (1)

Open questions attached to this trait. Seeded by just knowledge-gap-scan and curated; see the corpus-wide index.

Resolve a non-assay parent for positive methyl-red-test phenotypes before narrowing parent_traits below phenotype.

CURATION TODO RESOLVED methyl-red-test-positive-assay-parent-gap · raised by codex · 2026-09-12

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

METPO:1005013 is the seeded superclass of METPO:1005014, but METPO:1005013 defines an assay rather than a broader microbial trait class, so this record is temporarily parented directly to METPO:1000059 phenotype.

Resolution: METPO:1005013 is now represented as the seeded methyl-red-test assay parent, so this assay-outcome phenotype can use its exact source superclass instead of a temporary direct phenotype parent; this resolves the exact METPO assay-parent gap, not the broader non-assay parent question for assay-outcome phenotypes.

Curation history

  1. · SEEDED_FROM_METPO · seed_from_metpo

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

  2. · ENRICHED_FROM_LITERATURE · codex

    Added the METPO methyl-red-test-positive phenotype with stable-URL and DOI-backed methyl-red-test evidence after a repository-wide duplicate review covering ignored and hidden files.

  3. · CURATION_REVIEW_REVISION · codex

    Resolved PR #862 review issues #863 and #864 by removing a flattened Hansen Table 3 row from evidence snippets and narrowing the Hansen ASM Manual evidence note to match its quote.

  4. · RESOLVED_PARENT_GAP · codex

    Reparented methyl red test positive below the newly curated METPO:1005013 methyl red test assay parent and marked the temporary assay-parent discussion resolved.

  5. · CURATION_REVIEW_REVISION · codex

    Moved the methyl-red parent-gap closure into resolution_note and resolved_date so the original non-assay parent rationale remains visible.