temperature range

Deep research

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

# Curation report: microbial temperature range

## 1. Scope summary

**Target trait:** `METPO:1000306` (**temperature range**; ENVIRONMENT; CLASS; REVIEWED).

The trait should represent the **closed or operationally estimated interval of ambient temperatures supporting net microbial population growth under specified conditions**, conventionally bounded by minimum and maximum cardinal growth temperatures, *T*min and *T*max. In cardinal-temperature models, growth rate is zero below *T*min and above *T*max, while *T*opt is the temperature producing the maximum growth rate; therefore, *T*opt is a related parameter but is not the range itself. Rosso et al. explicitly model growth as zero for *T* < *T*min or *T* > *T*max. [DOI, published February 1995](https://doi.org/10.1128/aem.61.2.610-616.1995) (rosso1995convenientmodelto pages 1-2)

### Included

- Sustained vegetative or reproductive growth across a tested temperature series.
- Experimentally estimated *T*min and *T*max, including model-derived cardinal values when observations adequately bracket the boundaries.
- Genetically or physiologically mediated changes that expand, contract, or shift either growth boundary.
- Mechanisms that maintain membrane function, protein/RNA homeostasis, transport, bioenergetics, and redox balance sufficiently to permit growth near a boundary.

### Boundary cases and exclusions

1. **Not optimal growth temperature.** A change in *T*opt does not necessarily change range width or either boundary. In *Thermoanaerobacter kivui*, approximately 180 generations at 45°C shifted *T*opt from 66°C to 60°C, but the molecular basis and effects on the complete growth range remained unresolved. [DOI, published October 2023](https://doi.org/10.3389/fmicb.2023.1265216) (lehmann2023adaptivelaboratoryevolution pages 6-7, lehmann2023adaptivelaboratoryevolution pages 7-8)
2. **Not acute thermal survival.** Heat-shock resistance can be mechanistically opposed to growth at high temperature. Loss of `dnaJ` increased acute survival by 1,000–100,000-fold yet prevented sustained growth above 43°C in *Salmonella Typhimurium* and above 41°C in *E. coli*. [DOI, published 13 February 2024](https://doi.org/10.1128/mbio.03105-23) (berdejo2024evolutionarytradeoffbetween pages 8-10, berdejo2024evolutionarytradeoffbetween pages 1-2)
3. **Not dormancy or persistence.** A persister-like cell surviving heat without division does not establish that the organism grows at that temperature.
4. **Not metabolic activity alone.** Maintenance metabolism, substrate turnover, transcription, or viability without net population increase should be modeled separately.
5. **Not habitat temperature or isolation source.** Recovery from a hot spring, permafrost, or heated process is ecological evidence, not a measured growth range.
6. **Assay-conditioned phenotype.** Medium composition, pH, salinity, water activity, oxygen, pressure, substrate/loading rate, inoculum physiology, acclimation, observation duration, and detection threshold can alter an apparent boundary. Pressure is especially important above water’s normal boiling point; nutrient and osmotic conditions are likewise coupled to cold growth. Psychrophile literature emphasizes that pressure, salinity, oxidative stress, and nutrient availability interact with temperature. (damico2006psychrophilicmicroorganismschallenges pages 1-2)

**Recommended graph interpretation:** model *T*min and *T*max as two terminal boundary outcomes feeding the composite phenotype `METPO:1000306`, rather than treating “thermophile,” “psychrophile,” *T*opt, and heat-shock survival as interchangeable nodes.

## 2. Current mechanistic synthesis

Temperature range is an emergent systems phenotype. At the cold boundary, reduced reaction rates, membrane rigidification, impaired transport, stable inhibitory RNA structures, slow transcription/translation, protein folding defects, and possible ice formation jointly constrain growth. At the hot boundary, excess membrane fluidity/permeability, protein unfolding and aggregation, RNA/translation damage, redox imbalance, and loss of bioenergetic coupling become limiting. The authoritative psychrophile review lists “reduced enzyme activity,” “decreased membrane fluidity,” altered nutrient/waste transport, reduced transcription/translation/cell division, protein cold denaturation, inappropriate folding, and intracellular ice as cold-growth barriers. [DOI, published April 2006](https://doi.org/10.1038/sj.embor.7400662) (damico2006psychrophilicmicroorganismschallenges pages 1-2)

The strongest current graph architecture is therefore:

**ambient temperature → physicochemical damage/constraint → compensatory homeostasis module → retained cellular function → growth near boundary → temperature range.**

Recent research reinforces that no single universal mechanism determines the range. In 2024, a comparison of 2,739 thermal-performance datasets fitted to 83 models found no universal best mathematical model across traits and taxa, supporting explicit assay and taxon annotation rather than a universal curve assumption. [DOI, published October 2024](https://doi.org/10.1038/s41467-024-53046-2)

## 3. Candidate nodes grouped by type

### A. Trait and experimental nodes

- **temperature range** — `METPO:1000306`
- minimum growth temperature (*T*min) — retain label-only unless an approved METPO child is confirmed
- maximum growth temperature (*T*max) — label-only pending confirmed grounding
- optimal growth temperature (*T*opt) — related comparator, not part of the range definition
- ambient temperature; temperature upshift; temperature downshift; acute heat shock
- net population growth; maximum specific growth rate; doubling time; colony formation
- acclimation/pre-incubation, exposure duration, growth medium, pH, salinity, water activity, oxygen availability, hydrostatic pressure, nutrient/loading rate
- heat response — `GO:0009408`
- cold response — `GO:0009409`

### B. Membrane and lipid nodes

- plasma membrane — `GO:0005886`
- membrane fluidity/homeoviscous adaptation — label-only for the physical state/process unless a project-approved ontology term is available
- lipid metabolic process — `GO:0006629`
- fatty-acid biosynthetic process — `GO:0006633`
- saturated and unsaturated acyl-ACP pools
- phosphatidic acid, phosphatidylethanolamine, phosphatidylglycerol
- FabA, FabB, FabF, FabI, FabR, FadR, PlsB, PlsC — taxon-specific label nodes; add UniProt accessions only after strain selection
- glycerol dibiphytanyl glycerol tetraethers (GDGTs), cyclopentane rings, GrsA, GrsB

Showing the first 60 of 285 lines of findings; the linked file also carries the run's front matter and the prompt it was given — read the full report.