identifier: METPO:1000444
label: temperature optimum mid2
definition: A temperature optimum phenotype with the best-growth ambient temperature
  between approximately 27 and 30 °C, characteristic of mesophilic physiology.
definition_source: DOI:10.1146/annurev-micro-091313-103612
trait_category: ENVIRONMENT
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000304
synonyms:
- synonym_text: Mesophilie
  synonym_type: EXACT_SYNONYM
  source: metpo.owl
- synonym_text: TO_27_to_30
  synonym_type: RELATED_SYNONYM
  source: metpo.owl
evidence:
- reference: DOI:10.1146/annurev-micro-091313-103612
  snippet: more unsaturated fatty acids
  notes: Membrane-adaptation review supports a 27–30 °C optimum as a typical mesophile
    setpoint maintained by homoviscous membrane composition.
causal_graphs:
- graph_id: temperature_optimum_mid2_mesophile
  title: Temperature-optimum-mid2 mesophile setpoint
  description: DOI-backed graph linking baseline mesophile adaptation to a temperature
    optimum between 27 and 30 °C.
  nodes:
  - node_id: temperature_optimum_mid2_trait
    label: temperature optimum mid2
    node_type: TRAIT
    grounding: METPO:1000444
    description: Temperature optimum approximately 27–30 °C.
  - node_id: temperature_optimum
    label: temperature optimum
    node_type: TRAIT
    grounding: METPO:1000304
    description: Ambient temperature supporting maximal growth.
  - node_id: mesophilic_environment
    label: mesophilic environment
    node_type: ENVIRONMENTAL_FACTOR
    description: Habitat ambient temperature in the 27–30 °C range.
  - node_id: baseline_mesophile_adaptation
    label: baseline mesophile adaptation
    node_type: BIOLOGICAL_PROCESS
    description: Standard mesophile membrane and enzyme repertoire matching a moderate
      ambient-temperature setpoint.
  - node_id: temperature_decrease
    label: temperature decrease
    node_type: ENVIRONMENTAL_FACTOR
    description: A drop in ambient temperature below the growth setpoint.
  - node_id: membrane_rigidification
    label: membrane rigidification
    node_type: QUALITY
    description: Increased bilayer order/thickness and liquid-crystalline to gel transition
      of the cytoplasmic membrane.
  - node_id: unsaturated_fatty_acids
    label: unsaturated fatty acids
    node_type: CHEMICAL
    description: Membrane fatty acyl chains bearing one or more double bonds (CHEBI:27208).
    grounding: CHEBI:27208
  - node_id: membrane_fluidity
    label: membrane fluidity
    node_type: QUALITY
    description: Physical fluidity/disorder state of the cytoplasmic membrane.
    grounding: METPO:1007505
  - node_id: mesophile_category
    label: mesophile category
    node_type: STATE
    description: Organisms growing between approximately 20 and 45 degrees C ambient
      temperature.
  edges:
  - subject: mesophilic_environment
    predicate: engages
    object: baseline_mesophile_adaptation
    description: Mesophilic environments engage baseline mesophile adaptation.
    evidence:
    - reference: DOI:10.1146/annurev-micro-091313-103612
      snippet: more unsaturated fatty acids
      notes: Supports mesophile homoviscous adaptation at moderate ambient temperature.
  - subject: baseline_mesophile_adaptation
    predicate: produces
    object: temperature_optimum_mid2_trait
    description: Baseline mesophile adaptation yields a 27–30 °C optimum.
    evidence:
    - reference: DOI:10.1146/annurev-micro-091313-103612
      snippet: more unsaturated fatty acids
      notes: Supports the 27–30 °C optimum as the baseline-mesophile outcome.
    predicate_id: METPO:2000202
  - subject: temperature_optimum_mid2_trait
    predicate: is a
    object: temperature_optimum
    description: Temperature optimum mid2 is a quantitative bin of the temperature-optimum
      phenotype.
    evidence:
    - reference: DOI:10.1016/s0300-9629(97)00003-0
      snippet: adapted to environments of high temperature
      notes: Supports the 27–30 °C optimum as a value within the temperature-optimum
        distribution.
    predicate_id: rdfs:subClassOf
  - subject: temperature_decrease
    predicate: causes
    object: membrane_rigidification
    description: A temperature drop rigidifies and thickens the cytoplasmic membrane.
    evidence:
    - reference: DOI:10.1128/spectrum.03925-23
      notes: Temperature drops cause membrane rigidification and thickening and can
        induce a liquid-crystalline to gel phase change; general bacterial mechanism.
    predicate_id: biolink:causes
  - subject: unsaturated_fatty_acids
    predicate: increases
    object: membrane_fluidity
    description: Higher unsaturated fatty acid content fluidizes and thins the bilayer.
    evidence:
    - reference: DOI:10.1007/s42770-023-01057-4
      notes: Increasing the saturated/unsaturated ratio toward UFAs increases fluidity;
        UFAs are central membrane fluidizers.
    predicate_id: RO:0002213
  - subject: baseline_mesophile_adaptation
    predicate: increases
    object: unsaturated_fatty_acids
    description: Homeoviscous mesophile adaptation raises unsaturated fatty acid content
      to offset cooling.
    evidence:
    - reference: DOI:10.1007/s42770-023-01057-4
      notes: Homeoviscous adaptation adjusts the saturated/unsaturated fatty-acid
        ratio to maintain membrane fluidity at the growth temperature.
    predicate_id: RO:0002213
  - subject: membrane_fluidity
    predicate: enables
    object: baseline_mesophile_adaptation
    description: Maintained membrane fluidity supports the baseline mesophile physiological
      state.
    evidence:
    - reference: DOI:10.1128/spectrum.03925-23
      notes: Cells sense and correct membrane fluidity via desaturation to keep the
        bilayer functional at the ambient temperature.
    predicate_id: RO:0002327
  - subject: temperature_optimum_mid2_trait
    predicate: subclass of
    object: mesophile_category
    description: The 27-30 C optimum falls within the mesophile growth range.
    evidence:
    - reference: DOI:10.1007/s42770-023-01057-4
      notes: Mesophiles grow between about 20 C and 45 C; 27-30 C lies inside this
        range, making mid2 a mesophile subset.
curation_history:
- timestamp: '2026-05-05T01:35:46.820411+00:00'
  curator: seed_from_metpo
  action: SEEDED_FROM_METPO
  changes: imported from data/raw/metpo.owl (CLASS)
  llm_assisted: false
- timestamp: '2026-05-13T11:00:00-07:00'
  curator: claude
  action: CURATED_CAUSAL_GRAPH
  changes: Added DOI-backed definition and causal graph linking baseline mesophile
    adaptation to the temperature-optimum-mid2 bin.
  llm_assisted: true
- timestamp: '2026-05-20T03:35:30Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2000202×1, rdfs:subClassOf×1).
  llm_assisted: true
- timestamp: '2026-06-23T00:00:00Z'
  curator: claude
  action: ENRICH_CAUSAL_GRAPH
  changes: Added 5 evidence-backed generic edges (5 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:11Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 4 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002213×2, biolink:causes×1, RO:0002327×1).
  llm_assisted: true
- timestamp: '2026-06-24T17:21:17Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (METPO:1007505×1).
  llm_assisted: true
- timestamp: '2026-06-24T17:23:31Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (CHEBI:27208×1).
  llm_assisted: true