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temperature range mid4

METPO:1000453 · CLASS · REVIEWED

A temperature range phenotype in which the growth-supporting ambient temperature range spans approximately 34–40 °C, characteristic of warm-mesophilic physiology (including many mammalian host-associated bacteria).

Trait evidence (1)

Temperature-range-mid4 warm-mesophile context

DOI-backed nonmechanistic graph annotating warm-mesophile growth-range context, Fab-mediated homeoviscous membrane adaptation, compensatory membrane-fluidity restoration, high-temperature protein damage, and RpoH-governed heat-shock protection branches.

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-range-mid4 warm-mesophile context Interactive directed graph showing evidence-backed causal relationships for temperature range mid4.

Edge evidence

  • warm-mesophile adaptation confers temperature range mid4 METPO:2007700

    Warm-mesophile adaptation enables growth across 34–40 °C.

  • temperature range mid4 is a temperature range rdfs:subClassOf

    Temperature range mid4 is a quantitative bin of the temperature-range phenotype.

  • FabI/FabB fatty-acid branchpoint valve enables homeoviscous adaptation RO:0002327

    The FabI/FabB branchpoint valve reallocates flux between saturated and unsaturated fatty acid synthesis, enabling homeoviscous adaptation.

    • DOI:10.1038/s41467-024-53677-5 A first element of this regulatory system is a temperature-sensitive metabolic valve that allocates flux between the saturated and unsaturated fatty acid synthesis pathways via the branchpoint enzymes FabI and FabB Verified against the open Hoogerland et al. abstract; the E. coli temperature-sensitive metabolic valve allocates fatty-acid synthesis flux through FabI and FabB.
  • FabA/FabI/FabB competition for C10:1 pool regulates saturated/unsaturated membrane lipid composition RO:0002211

    Competition of FabA/FabI/FabB for the common C10:1 pool shifts flux between saturated and unsaturated fatty acids, changing saturated/unsaturated membrane lipid composition.

    • DOI:10.1038/s41467-024-53677-5 compete for a common pool of substrates Verified against the open Hoogerland et al. Figure 1 legend; FabA interconverts the C10:1 acyl-ACP substrates used by FabI and FabB, making the enzymes indirectly compete for one pool.
  • membrane fluidity restoration contributes to growth after temperature shock RO:0002326

    Valve plus transcriptional feedback restores optimal membrane fluidity within a single generation, contributing to growth after a temperature shock.

    • DOI:10.1038/s41467-024-53677-5 restores optimal membrane fluidity within a single generation Verified against the open Hoogerland et al. abstract; the measured E. coli fatty-acid and phospholipid pathway connects membrane-fluidity restoration to recovery from temperature shock.
  • heat stress causes protein unfolding and aggregation biolink:causes

    High temperatures cause protein unfolding and aggregation.

    • DOI:10.1186/s12864-023-09266-9 unfold or misfold proteins Verified against the open McGuire and Nano introduction; the review context lists unfolding, misfolding, and aggregation among the high-temperature cellular problems near TMAX.
  • protein unfolding and aggregation contributes to impaired mesophile growth RO:0002326

    Protein unfolding and aggregation contributes to mesophile growth impairment unless compensated.

    • DOI:10.1186/s12864-023-09266-9 Verified against the open McGuire and Nano introduction; the paper frames high-temperature RNA, protein, lipid, and DNA effects as cellular problems near the maximum growth temperature.
  • heat stress positively regulates membrane fluidity RO:0002213

    High temperatures increase membrane fluidity, requiring compensatory adaptation.

    • DOI:10.1186/s12864-023-09266-9 cause increased membrane fluidity Verified against the open McGuire and Nano introduction; increased membrane fluidity is listed as a high-temperature effect on cells.
  • compensatory membrane adaptation regulates membrane fluidity RO:0002211

    Compensatory membrane adaptation regulates temperature-driven membrane-fluidity changes.

    • DOI:10.1038/s41467-024-53677-5 hard-wired parameters calibrate the system to generate membrane compositions that maintain constant fluidity Verified against the open Hoogerland et al. introduction; homeoviscous adaptation counteracts temperature by varying unsaturated, branched-chain, or chain-length lipid features to stabilize viscosity.
  • sigma-32 (RpoH) heat-shock regulon positively regulates DnaK/DnaJ/GrpE and GroES/GroEL chaperone systems RO:0002213

    The sigma-32/RpoH regulon positively regulates the DnaK/DnaJ/GrpE and GroES/GroEL chaperone systems.

    • DOI:10.1128/mbio.03105-23 the alternative sigma factor σ32 (RpoH) that drives the expression of protective heat shock proteins (HSPs), such as the molecular chaperone systems DnaK/DnaJ/GrpE and GroES/GroEL Verified against the open Berdejo et al. introduction; RpoH is described as the main governor of the Salmonella Typhimurium heat-shock response and as driving protective heat-shock-protein expression.
  • DnaK/DnaJ/GrpE and GroES/GroEL chaperone systems enables protection against heat stress RO:0002327

    The DnaK/DnaJ/GrpE and GroES/GroEL chaperone systems protect against heat stress.

    • DOI:10.1128/mbio.03105-23 protective heat shock proteins Verified against the open Berdejo et al. introduction; DnaK/DnaJ/GrpE and GroES/GroEL are named as molecular chaperone systems in the protective heat-shock-protein response.

Provenance

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

Parent traits (1)

Synonyms (3)

  • Mesophilie EXACT_SYNONYM · metpo.owl
  • TR_34_to_40 RELATED_SYNONYM · metpo.owl
  • mesophilic EXACT_SYNONYM · https://w3id.org/metpo/releases/2026-06-12/metpo.owl

kg-microbe context

Matched 1 kg-microbe node via direct_metpo.

  • METPO:1000453 [-2.152, +0.301, -2.280, +3.386, …]

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_range_mid4-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-focused research report: **temperature range mid4**

## 1. Trait scope

**Trait:** `temperature range mid4`
**Identifier:** `METPO:1000453`
**Parent:** `METPO:1000306`
**Category:** environment
**Definition supplied for curation:** growth-supporting ambient-temperature range spanning approximately **34–40 °C**, characteristic of warm-mesophilic physiology, including many mammalian host-associated bacteria.

This trait should represent an **assay-observed capacity for net microbial growth over a temperature interval**, not merely survival after temperature exposure. Ideally, assignment should be supported by growth curves, colony formation, biomass accumulation, or repeated-transfer data at temperatures spanning or substantially overlapping 34–40 °C. It does not imply that every temperature in that interval is optimal.

### Boundaries and exclusions

* **Optimum versus range:** A reported optimum of 37 or 40 °C alone does not prove a growth-supporting range of 34–40 °C. Cardinal-temperature data—minimum, optimum, and maximum—or measurements at multiple temperatures are preferable.
* **Heat-shock response:** Transient induction of chaperones after a thermal upshift is not itself this phenotype. Acute heat shock can occur inside or outside an organism’s normal growth range.
* **Thermotolerance/thermoduricity:** Survival at 40 °C or after brief exposure to substantially higher temperatures does not establish sustained growth.
* **Thermophily:** A recent experimental-evolution paper operationally defined thermophiles as organisms with growth optima above 45 °C and mesophiles as having optima of 25–45 °C. Accordingly, `METPO:1000453` is a narrow warm-mesophile range class, not a generic thermophile class. (lehmann2023adaptivelaboratoryevolution pages 6-7)
* **Host-temperature sensing:** A shift to approximately 37 °C can activate virulence programs in pathogens, but that regulatory response should only enter this graph where it demonstrably contributes to growth or fitness across the target range. (samtani2022microbialmechanismsof pages 1-3)

## 2. Current mechanistic interpretation

The most defensible general mechanism is **temperature-dependent maintenance of membrane physical state**. Cooling orders the lipid bilayer, whereas warming increases fluidity. Microbes alter lipid unsaturation, branching, chain length, cyclization, and lipid-class abundance to keep membrane properties within a functional window. This preserves transport, respiration, permeability barriers, and membrane-protein activity. The *Bacillus subtilis* DesK–DesR–Des pathway supplies unusually strong causal evidence because membrane composition can activate the pathway at a constant 37 °C; thus DesK senses membrane physical state rather than temperature as an isolated variable. (mendoza2014temperaturesensingby pages 5-6)

A second module is **proteostasis**. Thermal upshifts increase protein damage and misfolding, inducing chaperones and proteases. Nevertheless, most retrieved chaperone evidence concerns acute heat stress rather than constitutive warm-mesophile growth. It should therefore be treated as a supporting or boundary-protection module, not automatically as the core cause of `METPO:1000453`. (samtani2022microbialmechanismsof pages 1-3)

## 3. Candidate graph nodes

### Environmental and assay nodes

* `METPO:1000453` — temperature range mid4, quoted verbatim as requested.
* Ambient temperature, 34–40 °C — label-only range node unless the project has an established temperature-bin vocabulary.
* Temperature decrease / cold shift.
* Temperature increase / thermal upshift.
* Sustained microbial growth — candidate grounding: `GO:0016049` (cell growth), subject to ontology-policy review.
* Acute heat shock — candidate biological-process grounding: `GO:0009408` (response to heat).
* Growth medium composition, oxygen availability, pH, incubation duration, inoculum state, and growth endpoint — experimental covariates that can shift observed temperature boundaries.

### Cellular structures and physical-state nodes

* Cytoplasmic membrane — `GO:0005886`.
* Membrane fluidity / membrane order — label-only physical-state nodes; avoid conflating them with membrane organization.
* Proton-motive force — `GO:0015988` is a possible process-level grounding for proton-motive-force-driven ATP synthesis, but a label-only “proton motive force” node may be more exact.
* Protein folding — `GO:0006457`.
* Protein aggregation / misfolded-protein burden — use label-only unless the exact intended ontology class is verified.

### Lipids and metabolites

* Unsaturated fatty acids — `CHEBI:27283`.
* Saturated fatty acids — `CHEBI:26607`.
* Branched-chain fatty acids — label-only candidate.
* Anteiso-branched-chain fatty acids — label-only candidate.
* Ladderane fatty acids/lipids — label-only candidate; taxon-specific to anammox Planctomycetota.
* Plasmalogens — `CHEBI:17762`.
* Oleic acid — `CHEBI:16196`, if a source specifically demonstrates its role.

### Genes, proteins, and complexes

**Strong *B. subtilis* module**

Showing the first 60 of 188 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.

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 warm-mesophile adaptation to the temperature-range-mid4 bin.

  3. · GROUND_CAUSAL_PREDICATES · claude

    Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002327×1, rdfs:subClassOf×1).

  4. · ENRICH_CAUSAL_GRAPH · claude

    Added 9 evidence-backed generic edges (14 new nodes) from the deep-research report.

  5. · GROUND_CAUSAL_PREDICATES · claude

    Grounded 7 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002327×3, biolink:causes×3, RO:0002211×1).

  6. · GROUND_CAUSAL_NODES · claude

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

  7. · MIGRATE_ENABLES_TRAIT_EDGES · claude

    Migrated 1 causal edge(s) off enables/RO:0002327 with a TRAIT object (1 to confers), issue 302. RO:0002327 has range 'biological process or activity', which a trait (a disposition) cannot satisfy, so the previous form entailed trait is-a BiologicalProcessOrActivity. The replacements are proposed in proposals/metpo_traitmech_v8 and are placeholder ids until METPO mints them.

  8. · 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_range_mid4_warm_mesophile=NONMECHANISTIC with scope_notes; marked 1 GENE_OR_PROTEIN node(s) REVIEWED_LABEL_ONLY with grounding_notes (chaperone_systems).

  9. · ADD_EXACT_ONTOLOGY_MATCH · codex

    Ontology exact-match review (2026-08-25): declared exact synonym(s): 'mesophilic'. Evidence is predicate-scoped in the versioned ontology snapshots; OAK cross-checked direct data, and OLS4 spot-checked release deltas and disputed hits.

  10. · ADD_CANONICAL_EXAMPLES · codex

    Resolved issue #444 after the #591 source/bin policy with 1 direct source-backed canonical example(s): Oceanimonas pelagia (NCBITaxon:3028314; DOI:10.1007/s10482-024-01948-y). The note retains the measured value or scopes broad-class examples to the cited branch; no paid research was used.

  11. · REVIEW_CAUSAL_EVIDENCE · codex

    Reviewed the temperature_range_mid4_warm_mesophile graph for issue #183: reviewed 9 edge-level evidence items, grounded the RpoH and compensatory-adaptation predicates, retained exact snippets where source wording directly supported the edge, and narrowed 2 local node identifiers to avoid cross-record type collisions. No paid research service was called.

  12. · CONNECT_CAUSAL_GRAPH_COMPONENTS · codex

    Resolved issue #183 graph fragmentation (6 components to 1) by adding 5 source- and verbatim-snippet-backed association connectors among Fab-mediated membrane adaptation, compensatory membrane-fluidity restoration, high-temperature protein damage, and RpoH heat-shock protection branches. No paid research service was called.

  13. · ADVERSARIAL_REVIEW_REPAIR · codex

    Addressed PR #664 adversarial review issue #667: dropped the weak protein-damage snippet from the protein_unfolding_aggregation to mesophile_growth_impairment edge while preserving its reference-backed review notes.

  14. · ADVERSARIAL_REVIEW_REPAIR · codex

    Addressed PR #664 adversarial review: replaced copied nonmechanistic bridge snippets with independent exact source snippets while preserving the existing connector edge scope.

  15. · ADVERSARIAL_REVIEW_REPAIR · codex

    Addressed PR #664 adversarial review issue #686: replaced fragmented ring-shape, soil-life-history, heat-shock, and ligninolysis snippets with exact source spans that carry their edge claims.

  16. · ADVERSARIAL_REVIEW_REPAIR · codex

    Addressed PR #664 adversarial review issue #689: expanded the Hoogerland FabI/FabB branch quote and replaced the warm-mesophile connector quote with an independent homeoviscous-adaptation span.

  17. · ADVERSARIAL_REVIEW_REPAIR · codex

    Addressed PR #664 adversarial review issues #698 and #699: removed sliced Hoogerland and heat-protection hub connectors and requoted the remaining compensatory membrane-fluidity edge.

  18. · ADVERSARIAL_REVIEW_REPAIR · codex

    Addressed PR #664 adversarial review issue #702: appended corrective issue-183 provenance after evidence-weak connectors were pruned; this NONMECHANISTIC graph intentionally ships with 6 disconnected components until independent trait-specific connectors are curated.

  19. · GROUND_CAUSAL_NODES · claude

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