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temperature delta high

METPO:1000487 · CLASS · REVIEWED

A temperature delta phenotype with a growth-supporting temperature breadth above approximately 30 °C, characteristic of extreme-eurythermal physiology.

Trait evidence (2)

  • DOI:10.1146/annurev-micro-091313-103612
    more unsaturated fatty acids

    Membrane-adaptation review supports very broad homoviscous remodeling capacity as the basis of extreme-eurythermal physiology.

  • DOI:10.1128/MMBR.65.1.1-43.2001
    resistant to irreversible inactivation at high temperatures

    Thermostable-protein review supports robust thermostability as the basis of extending tolerance beyond standard mesophile ranges.

Temperature-delta-high eurythermal context

DOI-backed nonmechanistic graph connecting maximal thermal-adaptation flexibility, cold-side homoviscous membrane remodeling, high-temperature membrane-viscosity shifts, and thermostable-enzyme context to the above-30-degrees-C temperature-delta bin.

NONMECHANISTIC · This record is a quantitative measurement, interval, or bin in the environmental phenotype hierarchy; a token protein example would misrepresent the measured value as one inherited molecular mechanism.

Temperature-delta-high eurythermal context Interactive directed graph showing evidence-backed causal relationships for temperature delta high.

Edge evidence

  • maximal thermal-adaptation flexibility confers temperature delta high METPO:2007700

    Maximal thermal-adaptation flexibility yields an extreme temperature-delta breadth.

    • DOI:10.1128/MMBR.65.1.1-43.2001 resistant to irreversible inactivation at high temperatures Supports maximal thermal-adaptation as the basis of extreme eurythermal breadth.
  • temperature delta high is a temperature delta rdfs:subClassOf

    Temperature delta high is a quantitative bin of the temperature-delta phenotype.

  • decreased growth temperature increases unsaturated fatty acid biosynthesis RO:0002213

    Lower growth temperature increases incorporation of unsaturated fatty acids (homoviscous adaptation).

    • DOI:10.1146/annurev-micro-091313-103612 incorporation of proportionally more unsaturated fatty acids Verified against the de Mendoza Annual Review abstract; bacterial membranes remodel by incorporating proportionally more unsaturated fatty acids as growth temperature decreases.
  • homoviscous adaptation contributes to membrane fluidity homeostasis RO:0002326

    Homoviscous adaptation contributes to membrane fluidity/permeability homeostasis across thermal shifts.

    • DOI:10.1146/annurev-micro-091313-103612 remodel the fluidity of their membrane bilayer Verified against the de Mendoza Annual Review abstract; homoviscous adaptation is the named membrane-fluidity remodeling process used after growth temperature decreases.
  • decreased membrane fluidity positively regulates unsaturated fatty acid biosynthesis RO:0002213

    Reduced membrane fluidity is sensed and positively regulates unsaturated fatty acid biosynthesis.

    • DOI:10.1146/annurev-micro-091313-103612 upregulate the biosynthesis of unsaturated fatty acids Verified against the de Mendoza Annual Review abstract; bacteria sense decreased membrane fluidity and initiate responses that upregulate unsaturated fatty acid biosynthesis.
  • lipid desaturase activity increases membrane fluidity RO:0002213

    Lipid desaturases introduce cis double bonds that loosen packing and increase fluidity.

    • DOI:10.3390/cells12101353 cis-double bonds, result in looser packing and increased fluidity Verified against the Wu et al. Cells review; lipid desaturase-generated cis double bonds loosen acyl-chain packing and increase membrane-bilayer fluidity.
  • increased short-/branched-/unsaturated fatty acids increases membrane fluidity RO:0002213

    Shifts in acyl chain length/branching and unsaturation jointly increase membrane fluidity at lower temperatures.

    • DOI:10.3390/cells12101353 increase the proportion of UFAs and short-chain fatty acids Verified against the Wu et al. Cells review; cold-adapted membranes can increase unsaturated and short-chain fatty acid proportions and modify branched-chain fatty-acid content.
  • hyperthermophilic enzyme thermostability prevents irreversible inactivation at high temperatures RO:0002212

    Intrinsic enzyme thermostability prevents irreversible inactivation, extending upper growth limits.

    • DOI:10.1128/MMBR.65.1.1-43.2001 resistant to irreversible inactivation at high temperatures Verified against the open Vieille and Zeikus review; hyperthermophilic enzymes are described as thermostable and resistant to irreversible inactivation at high temperatures.
  • unsaturated fatty acid biosynthesis contributes to homoviscous adaptation RO:0002326

    Unsaturated-fatty-acid biosynthesis contributes to cold-side homoviscous membrane remodeling.

    • DOI:10.1146/annurev-micro-091313-103612 termed homeoviscous adaptation Verified against the de Mendoza Annual Review abstract; this connector keeps unsaturated-fatty-acid biosynthesis as one component of the named membrane-fluidity adaptation rather than the whole response.
  • membrane fluidity associated with membrane fluidity homeostasis biolink:associated_with

    Membrane fluidity is associated with the homoviscous homeostasis branch of broad thermal adaptation.

    • DOI:10.3390/cells12101353 increase of unsaturated fatty acids in membrane phospholipids, which promotes membrane fluidity Verified against the Wu et al. Cells review; this connector keeps desaturase-linked fluidity as a physical membrane state associated with homeostasis.
  • membrane viscosity at higher temperature associated with membrane fluidity homeostasis biolink:associated_with

    High-temperature membrane viscosity is associated with the warming-side boundary of membrane-fluidity homeostasis.

    • DOI:10.3390/cells12101353 trans-UFA generation elevates the viscosity of the membrane Verified against the Wu et al. Cells review; this connector keeps cis-trans isomerization as warming-side membrane context.
  • membrane fluidity homeostasis associated with maximal thermal-adaptation flexibility biolink:associated_with

    Membrane-fluidity homeostasis is associated with the broad thermal-adaptation context used to represent an extreme temperature-growth breadth.

    • DOI:10.1146/annurev-micro-091313-103612 molecular strategies to sense changes in membrane fluidity Verified against the de Mendoza Annual Review abstract; this connector scopes homoviscous adaptation as membrane context for the eurythermal bin.
  • hyperthermophilic enzyme thermostability associated with maximal thermal-adaptation flexibility biolink:associated_with

    Thermostable-enzyme protection is associated with the high-temperature side of broad thermal adaptation.

    • DOI:10.1128/MMBR.65.1.1-43.2001 are typically thermostable (i.e., resistant to irreversible inactivation at high temperatures) and are optimally active at high temperatures Verified against the open Vieille and Zeikus review; this connector keeps thermostable enzymes as high-temperature context rather than direct proof of an above-30-degrees-C growth breadth.

Provenance

Identifier source
METPO (2026-06-12)
Definition source
DOI:10.1146/annurev-micro-091313-103612

Parent traits (1)

Synonyms (1)

  • Td_>30 RELATED_SYNONYM · metpo.owl

kg-microbe context

Matched 1 kg-microbe node via direct_metpo.

  • METPO:1000487 [-0.692, +0.274, -0.785, +3.229, …]

512-dim DeepWalkSkipGramEnsmallen embedding from kg-microbe (2026-04-25).

Nearest neighbors in embedding space

Top-8 cosine-similar METPO traits from the 2026-04-25 deepwalk (512-D).

Deep research

Generated by just research-trait; source: research/traits/environment/temperature_delta_high-deep-research-falcon.md

Unreviewed literature output — not curated TraitMech content Ontology identifiers suggested below have not been resolved against their ontologies, and some are known to be wrong. Check any CURIE against the source before using it. 
# Curation report: microbial “temperature delta high”

## Executive assessment

**Trait:** “temperature delta high”
**Identifier:** `METPO:1000487`
**Parent:** `METPO:1000303`
**Category:** ENVIRONMENT; **term kind:** CLASS; **mapping:** REVIEWED
**Operational definition:** a microbial phenotype in which reproducible growth is supported across a temperature interval, \(T_{max}-T_{min}\), greater than approximately 30°C.

The strongest exemplar recovered is *Exiguobacterium chiriqhucha* RW2, which grew from **4–50°C**, a 46°C breadth and the broadest reported range among the examined *Exiguobacterium* isolates. Its membrane phospholipid composition was measured at 4, 18, 30, and 50°C; iso-C17:1Δ5 declined from **17.0 ± 0.5 mol% at 4°C to 1.1 ± 0.3 mol% at 50°C**, a reduction exceeding 93%. This directly anchors the phenotype and strongly associates temperature-dependent membrane remodeling with it, although it does not prove that the lipid change is sufficient or necessary for the full breadth. (white2019thecompletegenome pages 17-18, white2019thecompletegenome pages 10-11, white2019thecompletegenome pages 7-9)

The best-supported mechanistic architecture is therefore **modular rather than a single pathway**:

1. low-temperature membrane sensing and homoviscous lipid remodeling;
2. RNA remodeling and maintenance of translation at the cold end;
3. chaperone/protease-mediated proteostasis and protein thermostability at the warm end;
4. possibly compatible-solute and antioxidant systems that protect membranes and macromolecules.

Only the first three have evidence strong enough to contribute selected graph edges, and even these differ substantially in evidential strength. Recent 2023 literature consolidates bacterial temperature-response mechanisms, but the search found little 2023–2024 work that directly perturbs a mechanism and demonstrates a **greater-than-30°C growth breadth**. Most recent studies address one thermal endpoint or acute survival rather than eurythermal growth. (moon2023temperaturemattersbacterial pages 7-9)

## 1. Trait scope and boundaries

### Included phenotype

A positive annotation should require:

- measured microbial growth—not merely viability—at multiple temperatures;
- documented lower and upper growth limits, or sufficient tested points to establish a breadth above approximately 30°C;
- comparable medium, pH, salinity, oxygenation, inoculum, and incubation criteria across temperatures;
- preferably serial propagation or quantitative growth curves near both endpoints.

RW2 is a strong positive example because growth was reported over 4–50°C and lipid analyses used cultures grown at 4, 18, 30, and 50°C. The strain also tolerates pH 5–11 and varying salinity, emphasizing that assay covariates must be represented separately rather than folded into the temperature trait. (white2019thecompletegenome pages 17-18, white2019thecompletegenome pages 7-9, white2019thecompletegenome pages 3-4)

### Excluded or adjacent phenotypes

- **Thermophily/hyperthermophily:** describes a high optimum or high growth range, not necessarily a range wider than 30°C. Hyperthermophilic enzymes can remain active and resist irreversible inactivation at high temperature, but that does not establish low-temperature growth.
- **Psychrophily/psychrotolerance:** establishes low-temperature growth, not a high upper limit.
- **Heat-shock or cold-shock survival:** survival after an acute exposure is not equivalent to sustained growth.
- **Thermotolerance of spores or resting states:** should not be transferred automatically to vegetative growth.
- **Broad enzyme activity range:** an isolated enzyme is not an organism-level growth phenotype.
- **Temperature optimum:** one optimum value cannot determine \(T_{max}-T_{min}\).

For example, recombinant CspL substantially improves growth at elevated temperature, but the tested spans do not establish a >30°C breadth. It is evidence for a component mechanism, not direct evidence of `METPO:1000487`. (zhou2021acoldshock pages 5-6, zhou2021acoldshock pages 1-2)

## 2. Candidate nodes and ontology grounding

Identifiers below are included only where grounding is sufficiently clear. Gene symbols, strain-specific lipids, and complexes should remain label-only until reconciled against the exact TraitMech ontology import and taxon-specific database records.

### Trait, taxa, and environmental/experimental nodes

- `METPO:1000487` — temperature delta high.
- `METPO:1000303` — supplied parent trait.
- *Exiguobacterium chiriqhucha* RW2 — exemplar taxon/strain; **label-only pending NCBITaxon verification**.
- *Bacillus subtilis* — DesK/DesR/des model organism; use a verified NCBITaxon CURIE during implementation.
- *Bacillus coagulans* 2-6 — CspL source strain; label-only pending strain-level verification.
- low temperature; high temperature; temperature downshift; heat shock; cold shock — environmental or experimental nodes; map to ENVO or assay ontology terms only after exact term verification.
- growth-supporting temperature minimum, maximum, and breadth — assay-derived quantities; preserve the temperatures, medium, atmosphere, duration, and growth criterion as evidence metadata.

### Genes, proteins, and complexes

Showing the first 60 of 211 lines of findings; the linked file also carries the run's front matter and the prompt it was given — read the full report.

Canonical examples (1)

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

  • Exiguobacterium chiriqhucha NCBITaxon:1385984 DOI:10.3389/fmicb.2018.03189 Eurythermal firmicute whose strain RW2 was grown across 4-50 degrees C on M-medium, a 46 degrees C breadth and the broadest reported for the genus; membrane phospholipid composition was measured at 4, 18, 30 and 50 degrees C, confirming growth at both endpoints rather than mere survival.

Curation history

  1. · SEEDED_FROM_METPO · seed_from_metpo

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

  2. · CURATED_CAUSAL_GRAPH · claude

    Added DOI-backed definition and causal graph linking maximal thermal-adaptation flexibility to the eurythermal temperature-delta-high bin.

  3. · GROUND_CAUSAL_PREDICATES · claude

    Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (METPO:2000202×1, rdfs:subClassOf×1).

  4. · ENRICH_CAUSAL_GRAPH · claude

    Added 7 evidence-backed generic edges (12 new nodes) from the deep-research report.

  5. · GROUND_CAUSAL_PREDICATES · claude

    Grounded 4 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002213×4).

  6. · GROUND_CAUSAL_NODES · claude

    Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (METPO:1007505×1).

  7. · GROUND_CAUSAL_NODES · claude

    Grounded 2 causal-node grounding field(s) via mappings/node_grounding.tsv (GO:0006636×1, GO:0016859×1).

  8. · MIGRATE_MICROBE_DOMAIN_EDGES · claude

    Re-grounded 1 causal edge(s) off microbe-domain METPO predicates (1 to confers), issue 301. The previous predicates are transitively rdfs:subPropertyOf METPO:2000001, whose rdfs:domain is METPO:1000525 (microbe), so a causal-graph subject entailed that the subject IS a microbe; CausalNodeTypeEnum has no organism member, so no such edge could ever satisfy the domain. Edge directions are unchanged - this pass only relabels and re-grounds. RO:0002234 (has output) is used where the subject is an activity, since biolink gives it the domain 'biological process or activity'; the METPO replacements are proposed in proposals/metpo_traitmech_v8 and v9 and are placeholder ids until METPO mints them.

  9. · NORMALISE_NODE_TYPE · claude

    Normalised causal-node type(s) so one node_id means one thing corpus-wide (issue 356): membrane_fluidity_homeostasis: STATE -> BIOLOGICAL_PROCESS. The counterpart of the above, and the reason the rename was not needed: this id already exists for the process sense. Both occurrences describe 'Maintenance of membrane fluidity ...', and the schema's STATE definition excludes exactly this -- 'the state is the gradient / steady-value, NOT ITS ESTABLISHMENT'. Maintenance is establishment. So the STATE-typed one (temperature_delta_high.yaml) is retyped to match the process it describes.

  10. · BACKFILL_CANONICAL_EXAMPLES · claude

    Added one exemplar taxon, Exiguobacterium chiriqhucha (strain RW2), the only organism this trait's deep-research artifact establishes as an instance of the >30 C breadth bin -- growth measured over 4-50 C, a 46 C delta. Taxon id resolved and label-checked against the local NCBITaxon build; reference taken from the artifact. Deliberately excluded, all named in the same artifact but as mechanism or contrast cases rather than instances of the bin - Shewanella frigidimarina (4-30 C is a 26 C delta, which the artifact says "falls below the proposed >30 C threshold" and "should not be used as a positive trait anchor" without additional endpoint data); Bacillus subtilis (source of the DesK/DesR/des cold-end module, no breadth measured); Escherichia coli, Pseudomonas putida and Saccharomyces cerevisiae (heterologous CspL hosts showing warm-end growth gains only, which the artifact warns "does not demonstrate >30 C breadth"); Bacillus coagulans (CspL source strain, no breadth measured).

  11. · REVIEW_GRAPH_PROTEIN_TAXON · claude

    Backfilled provenance (review issue 517) for the codex protein-taxon review tranche of 2026-08-24/25, which shipped without a per-record event. In this record the tranche: set graph scope temperature_delta_high_eurythermal=NONMECHANISTIC with scope_notes.

  12. · REVIEW_CAUSAL_EVIDENCE · codex

    Reviewed the temperature_delta_high_eurythermal graph for issue #183: added snippets to 7 edge-level evidence items and grounded 3 unmapped homoviscous-adaptation and thermostability predicates to RO:0002326, RO:0002213, or RO:0002212. No paid research service was called.

  13. · CONNECT_CAUSAL_GRAPH_COMPONENTS · codex

    Resolved issue #183 graph fragmentation (6 components to 1) by adding 5 source- and verbatim-snippet-backed association or contribution connectors among cold UFA synthesis, homoviscous adaptation, membrane-fluidity, high-temperature membrane-viscosity, and thermostable-enzyme branches. No paid research service was called.

  14. · ADVERSARIAL_REVIEW_REPAIR · codex

    Addressed PR #664 adversarial review: requoted the de Mendoza membrane-fluidity adaptation evidence with the exact homeoviscous spelling from the cited source.

  15. · ADVERSARIAL_REVIEW_REPAIR · codex

    Addressed PR #664 adversarial review issue #692: requoted the Wu et al. trans-UFA connector snippet without the markup-flattening space before the hyphen.

  16. · ADVERSARIAL_REVIEW_REPAIR · codex

    Addressed PR #664 adversarial review issue #700: removed the unsupported cis-trans-isomerase high-temperature membrane-viscosity edge and its abandoned isomerase node.

  17. · GROUND_CAUSAL_NODES · claude

    Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (METPO:1016200×1).