identifier: METPO:1000304
label: temperature optimum
definition: A temperature phenotype with numerical limits that represents the ambient-temperature
  conditions at which an organism exhibits the most efficient growth and reproduction.
definition_source: DOI:10.1016/s0300-9629(97)00003-0
trait_category: ENVIRONMENT
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000533
- METPO:1000536
created_by: Anthea Guo
evidence:
- reference: DOI:10.1016/s0300-9629(97)00003-0
  snippet: adapted to environments of high temperature
  notes: Thermophile-adaptation review supports the ambient temperature at which membrane
    and enzyme function are best maintained as the operational definition of temperature
    optimum.
- reference: DOI:10.1146/annurev-micro-091313-103612
  snippet: more unsaturated fatty acids
  notes: Membrane-adaptation review supports homoviscous membrane composition as a
    key mechanism setting the temperature optimum.
causal_graphs:
- graph_id: temperature_optimum_balanced_adaptation
  title: Temperature-optimum balanced adaptation
  description: DOI-backed graph linking the ambient temperature at which membrane
    fluidity, protein folding, and enzyme kinetics jointly maintain maximal growth
    to the temperature-optimum phenotype.
  nodes:
  - node_id: temperature_optimum_trait
    label: temperature optimum
    node_type: TRAIT
    grounding: METPO:1000304
    description: Ambient temperature at which growth rate is maximal.
  - node_id: ambient_temperature
    label: ambient temperature
    node_type: ENVIRONMENTAL_FACTOR
    description: Ambient growth temperature imposed on the cell.
  - node_id: membrane_fluidity
    label: membrane fluidity
    node_type: QUALITY
    description: Physical state of the cytoplasmic membrane supporting transport and
      bioenergetics.
    grounding: METPO:1007505
  - node_id: homoviscous_lipid_composition
    label: homoviscous lipid composition
    node_type: CELLULAR_LOCALIZATION
    description: Lipid composition tuned to maintain a target fluidity at the growth
      temperature.
  - node_id: enzyme_kinetics
    label: enzyme kinetics
    node_type: BIOLOGICAL_PROCESS
    description: Temperature dependence of enzyme turnover for biosynthesis and energy
      conservation.
  - node_id: maximal_growth_rate
    label: maximal growth rate
    node_type: BIOLOGICAL_PROCESS
    description: Peak specific growth rate achieved at the optimal temperature.
  - node_id: homeoviscous_adaptation
    label: homeoviscous adaptation
    node_type: BIOLOGICAL_PROCESS
    description: Generic lipid-remodeling strategy that maintains a target membrane
      physical state (fluidity) across growth temperatures.
  - node_id: arrhenius_plot_deviation
    label: Arrhenius plot deviation from linearity
    node_type: EXPERIMENTAL_FACTOR
    description: Departure from a linear growth-rate-vs-temperature Arrhenius relationship
      used to interpret temperature-response measurements.
  - node_id: stress_growth_regime
    label: stress / non-physiological growth regime
    node_type: STATE
    description: Growth condition outside the physiological temperature range, indicated
      by non-linear Arrhenius behavior.
  edges:
  - subject: ambient_temperature
    predicate: regulates
    object: membrane_fluidity
    description: Ambient temperature sets a target membrane fluidity that the cell
      must match.
    evidence:
    - reference: DOI:10.1146/annurev-micro-091313-103612
      snippet: more unsaturated fatty acids
      notes: Supports temperature as the input to membrane-fluidity adaptation.
    predicate_id: RO:0002211
  - subject: homoviscous_lipid_composition
    predicate: regulates
    object: membrane_fluidity
    description: Homoviscous lipid composition maintains target membrane fluidity
      at the optimum temperature.
    evidence:
    - reference: DOI:10.1146/annurev-micro-091313-103612
      snippet: more unsaturated fatty acids
      notes: Supports homoviscous adaptation as the mechanism setting membrane fluidity.
    predicate_id: RO:0002211
  - subject: ambient_temperature
    predicate: regulates
    object: enzyme_kinetics
    description: Ambient temperature scales enzyme turnover rates across the cellular
      network.
    evidence:
    - reference: DOI:10.1016/s0300-9629(97)00003-0
      snippet: energy transducing enzymes
      notes: Supports temperature as the determinant of enzyme function in adapted
        organisms.
    predicate_id: RO:0002211
  - subject: enzyme_kinetics
    predicate: enables
    object: maximal_growth_rate
    description: Adequately fast enzyme kinetics enable peak growth at the optimal
      temperature.
    evidence:
    - reference: DOI:10.1016/s0300-9629(97)00003-0
      snippet: adapted to environments of high temperature
      notes: Supports balanced enzyme kinetics at adapted temperature as the basis
        of peak growth.
    predicate_id: RO:0002327
  - subject: maximal_growth_rate
    predicate: manifests as
    object: temperature_optimum_trait
    description: The ambient temperature supporting peak growth manifests the temperature-optimum
      phenotype.
    evidence:
    - reference: DOI:10.1016/s0300-9629(97)00003-0
      snippet: adapted to environments of high temperature
      notes: Supports the trait endpoint.
    predicate_id: METPO:2007400
  - subject: homeoviscous_adaptation
    predicate: regulates
    object: membrane_fluidity
    description: Homeoviscous adaptation remodels membrane lipids to maintain target
      fluidity across temperatures.
    evidence:
    - reference: DOI:10.1007/s42770-023-01057-4
      notes: 'Broad bacterial review: ''to maintain membrane fluidity at low temperature
        organisms alter membrane lipid composition (homeoviscous adaptation)''.'
    predicate_id: RO:0002211
  - subject: membrane_fluidity
    predicate: enables
    object: maximal_growth_rate
    description: Membrane physical state (fluidity) is a proximal determinant of growth,
      constraining transport, signaling, and division required for peak growth.
    evidence:
    - reference: DOI:10.1007/s42770-023-01057-4
      notes: Membrane fluidity maintenance via homeoviscous adaptation supports the
        cellular processes underlying growth across the temperature range.
    predicate_id: RO:0002327
  - subject: arrhenius_plot_deviation
    predicate: indicates
    object: stress_growth_regime
    description: Deviation from Arrhenius linearity in growth-rate-vs-temperature
      data marks a stress / non-physiological growth regime, bounding the optimum.
    evidence:
    - reference: DOI:10.37256/amtt.5220244537
      notes: '''Arrhenius plots, with linear regions indicating physiological growth
        and deviations indicating stress''.'
curation_history:
- timestamp: '2026-05-05T01:35:46.813650+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 causal graph linking ambient temperature, homoviscous
    membrane adaptation, enzyme kinetics, and maximal growth to the temperature-optimum
    phenotype.
  llm_assisted: true
- timestamp: '2026-05-20T03:35:30Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002327×1).
  llm_assisted: true
- timestamp: '2026-05-23T21:30:06Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2007400×1).
  llm_assisted: true
- timestamp: '2026-05-24T04:13:18Z'
  curator: claude
  action: RENAME_PREDICATE_LABELS
  changes: 'Renamed 1 causal-edge predicate label(s) to align with existing groundings:
    maintains → regulates ×1.'
  llm_assisted: true
- timestamp: '2026-05-24T04:13:21Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002211×1).
  llm_assisted: true
- timestamp: '2026-05-24T04:41:03Z'
  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: '2026-05-26T02:30:13Z'
  curator: claude
  action: RETYPE_CAUSAL_NODES
  changes: 'Re-typed 1 causal-node node_type field(s) to align with CausalNodeTypeEnum
    semantics: membrane fluidity: BIOLOGICAL_PROCESS → QUALITY ×1.'
  llm_assisted: true
- timestamp: '2026-05-26T05:00:47Z'
  curator: claude
  action: RENAME_PREDICATE_LABELS
  changes: 'Renamed 2 causal-edge predicate label(s) to align with existing groundings:
    influences → regulates ×2.'
  llm_assisted: true
- timestamp: '2026-05-26T05:00:50Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002211×2).
  llm_assisted: true
- timestamp: '2026-06-23T00:00:00Z'
  curator: claude
  action: ENRICH_CAUSAL_GRAPH
  changes: Added 3 evidence-backed generic edges (3 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:11Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002211×1, RO:0002327×1).
  llm_assisted: true