identifier: METPO:1000303
label: temperature delta
definition: A temperature phenotype with numerical limits expressing the breadth (maximum
  minus minimum, in °C) of ambient temperatures supporting growth of an organism.
definition_source: DOI:10.1016/s0300-9629(97)00003-0
trait_category: ENVIRONMENT
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000533
- METPO:1000534
evidence:
- reference: DOI:10.1016/s0300-9629(97)00003-0
  snippet: adapted to environments of high temperature
  notes: Thermophile-adaptation review supports the breadth of the temperature-tolerance
    span as a derived descriptor reflecting overall thermal-adaptation flexibility.
- reference: DOI:10.1146/annurev-micro-091313-103612
  snippet: more unsaturated fatty acids
  notes: Membrane-adaptation review supports homoviscous remodeling capacity as the
    basis of broad versus narrow temperature tolerance.
causal_graphs:
- graph_id: temperature_delta_thermal_flexibility
  title: Temperature-delta thermal-adaptation flexibility
  description: DOI-backed graph linking the flexibility of membrane and enzyme adaptation
    to the breadth of the temperature growth range (delta = max − min).
  nodes:
  - node_id: temperature_delta_trait
    label: temperature delta
    node_type: TRAIT
    grounding: METPO:1000303
    description: Breadth of the growth-supporting ambient-temperature range.
  - node_id: thermal_adaptation_flexibility
    label: thermal-adaptation flexibility
    node_type: BIOLOGICAL_PROCESS
    description: Capacity to remodel membrane lipid composition and enzyme repertoire
      across a wide span of ambient temperatures.
  - node_id: tolerance_breadth
    label: temperature tolerance breadth
    node_type: BIOLOGICAL_PROCESS
    description: Span between the minimum and maximum growth-supporting ambient temperatures.
  - node_id: unsaturated_fatty_acids
    label: unsaturated fatty acids
    node_type: CHEMICAL
    description: Fatty acids bearing cis double bonds incorporated into membrane lipids.
    grounding: CHEBI:27208
  - node_id: membrane_fluidity
    label: membrane fluidity
    node_type: QUALITY
    description: Physical state of the lipid bilayer; higher fluidity corresponds
      to lower lipid order and lower transition temperature.
    grounding: METPO:1007505
  - node_id: anteiso_branched_chain_fatty_acids
    label: anteiso-branched-chain fatty acids
    node_type: CHEMICAL
    description: Branched-chain fatty acids that disrupt lipid packing and lower the
      membrane transition temperature.
  - node_id: low_temperature_growth
    label: membrane function and growth at low temperature
    node_type: BIOLOGICAL_PROCESS
    description: Maintenance of membrane function supporting growth at the low-temperature
      end of the range.
  edges:
  - subject: thermal_adaptation_flexibility
    predicate: enables
    object: tolerance_breadth
    description: Thermal-adaptation flexibility enables broad temperature tolerance.
    evidence:
    - reference: DOI:10.1146/annurev-micro-091313-103612
      snippet: more unsaturated fatty acids
      notes: Supports membrane-remodeling flexibility as the basis of broad thermal
        tolerance.
    predicate_id: RO:0002327
  - subject: tolerance_breadth
    predicate: manifests as
    object: temperature_delta_trait
    description: The breadth between minimum and maximum growth-supporting ambient
      temperatures manifests the temperature-delta phenotype.
    evidence:
    - reference: DOI:10.1016/s0300-9629(97)00003-0
      snippet: adapted to environments of high temperature
      notes: Supports the trait endpoint via thermal adaptation across a span.
    predicate_id: METPO:2007400
  - subject: unsaturated_fatty_acids
    predicate: increases
    object: membrane_fluidity
    description: cis-Unsaturated fatty acids disrupt lipid packing, lower the membrane
      transition temperature, and increase fluidity.
    evidence:
    - reference: DOI:10.1146/annurev-micro-091313-103612
      notes: cis-unsaturated fatty acids disrupt packing, lower Tm, and increase fluidity;
        foundational and broadly applicable.
    predicate_id: RO:0002213
  - subject: unsaturated_fatty_acids
    predicate: supports
    object: low_temperature_growth
    description: Incorporation of more unsaturated fatty acids optimizes membrane
      function for growth at lower temperatures, extending the low-temperature end
      of the range.
    evidence:
    - reference: DOI:10.1146/annurev-micro-091313-103612
      notes: bacteria respond to decreasing growth temperature by incorporating proportionally
        more unsaturated fatty acids, optimizing cellular processes at the new temperature.
  - subject: anteiso_branched_chain_fatty_acids
    predicate: increases
    object: membrane_fluidity
    description: Anteiso-branched-chain fatty acids disrupt lipid packing and lower
      the membrane transition temperature, increasing fluidity.
    evidence:
    - reference: DOI:10.1146/annurev-micro-091313-103612
      notes: anteiso-branched-chain fatty acids (a-BCFAs) disrupt packing, lower Tm;
        generalized across bacteria using branched lipids.
    predicate_id: RO:0002213
  - subject: anteiso_branched_chain_fatty_acids
    predicate: required for
    object: low_temperature_growth
    description: Membrane function and growth at low temperature require both anteiso-branched-chain
      fatty acids and unsaturated fatty acids.
    evidence:
    - reference: DOI:10.1146/annurev-micro-091313-103612
      notes: Membrane function/growth at low temperature requires both anteiso-branched-chain
        fatty acids (a-BCFAs) and unsaturated fatty acids (UFAs).
  - subject: low_temperature_growth
    predicate: contributes to
    object: tolerance_breadth
    description: Supporting growth at the low-temperature end widens the span between
      minimum and maximum growth-supporting temperatures.
    evidence:
    - reference: DOI:10.1146/annurev-micro-091313-103612
      notes: Membrane homeoviscous adaptation extends low-temperature growth, broadening
        the temperature tolerance span (delta).
    predicate_id: RO:0002326
curation_history:
- timestamp: '2026-05-05T01:35:46.812991+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 thermal-adaptation flexibility to
    the temperature-delta breadth 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: '2026-06-23T00:00:00Z'
  curator: claude
  action: ENRICH_CAUSAL_GRAPH
  changes: Added 5 evidence-backed generic edges (4 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:11Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 3 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002213×2, RO:0002326×1).
  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