identifier: METPO:1005015
label: methyl red test negative
definition: A phenotype in which an organism tests negative in the methyl red test.
trait_category: OTHER
term_kind: CLASS
mapping_status: SEEDED
parent_traits:
- METPO:1005013
curation_history:
- timestamp: '2026-09-12T18:34:21Z'
  curator: seed_from_metpo
  action: SEEDED_FROM_METPO
  changes: imported from data/raw/metpo.owl (CLASS)
- timestamp: '2026-09-12T18:38:59Z'
  curator: codex
  action: ENRICHED_FROM_LITERATURE
  changes: Added the METPO methyl-red-test-negative phenotype with stable-URL and
    DOI-backed methyl-red-test evidence after a repository-wide duplicate review covering
    ignored and hidden files.
  llm_assisted: true
- timestamp: '2026-09-12T18:57:06Z'
  curator: codex
  action: CURATION_REVIEW_REVISION
  changes: 'Added the Hansen Klebsiella pneumoniae canonical example after local review
    issue #861 showed Table 2 directly supports a mostly methyl-red-negative Klebsiella
    pneumoniae result.'
  llm_assisted: true
- timestamp: '2026-09-12T20:15:55Z'
  curator: codex
  action: RESOLVED_PARENT_GAP
  changes: Reparented methyl red test negative below the newly curated METPO:1005013
    methyl red test assay parent and marked the temporary assay-parent discussion
    resolved.
  llm_assisted: true
- timestamp: '2026-09-12T20:44:24Z'
  curator: codex
  action: CURATION_REVIEW_REVISION
  changes: Moved the methyl-red parent-gap closure into resolution_note and resolved_date
    so the original non-assay parent rationale remains visible.
  llm_assisted: true
definition_source: https://asm.org/getmedia/40946f85-9357-4563-aa8a-994427efa825/Methyl-Red-and-Voges-Proskauer-Test-Protocols.pdf
evidence:
- reference: https://asm.org/getmedia/40946f85-9357-4563-aa8a-994427efa825/Methyl-Red-and-Voges-Proskauer-Test-Protocols.pdf
  snippet: A negative MR test is indicated by a yellow color in the culture medium
    (Fig. 1B), which occurs when less acid is produced (pH is higher) from the fermentation
    of glucose.
  notes: The ASM protocol PDF defines the negative methyl-red-test readout as a yellow
    culture after methyl red is added, reflecting less acidification during glucose
    fermentation.
- reference: DOI:10.1128/JCM.42.8.3665-3669.2004
  snippet: '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'
  notes: Hansen et al. evaluated methyl red as a conventional Klebsiella biochemical
    test; their Table 2 reports K. pneumoniae methyl-red result percentages across
    CPHL, NRL, and SSI.
- reference: DOI:10.1128/JCM.42.8.3665-3669.2004
  snippet: 'Variable results were of two types: (i) those in which all three laboratories
    found a mixture of positive and negative results among the representatives of
    a species for a specific test (e.g., K. pneumoniae and l-sorbose), suggesting
    a truly variable reaction, and (ii) those in which one center found most strains
    to be negative while another found most positive (e.g., K. rhinoscleromatis and
    MR) or vice versa, suggesting that the results were method dependent.'
  notes: The same interlaboratory evaluation found that MR could be method dependent
    for some Klebsiella species/test combinations, so the K. pneumoniae canonical
    example is recorded from Table 2 results rather than treated as a species-wide
    invariant.
canonical_examples:
- taxon_id: NCBITaxon:573
  taxon_label: Klebsiella pneumoniae
  note: 'Hansen et al. Table 2 reported mostly methyl-red-negative results for K.
    pneumoniae across three reference laboratories: 10.7%, 3.6%, and 10.7% MR-positive
    strains.'
  reference: DOI:10.1128/JCM.42.8.3665-3669.2004
discussions:
- discussion_id: methyl-red-test-negative-assay-parent-gap
  prompt: Resolve a non-assay parent for negative methyl-red-test phenotypes before
    narrowing parent_traits below phenotype.
  kind: CURATION_TODO
  status: RESOLVED
  rationale: METPO:1005013 is the seeded superclass of METPO:1005015, but METPO:1005013
    defines an assay rather than a broader microbial trait class, so this record is
    temporarily parented directly to METPO:1000059 phenotype.
  posed_by: codex
  posed_date: '2026-09-12'
  resolved_date: '2026-09-12'
  resolution_note: 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.