temperature range mid3

Deep research

Generated by just research-trait; source: research/traits/environment/temperature_range_mid3-deep-research-falcon.md

# Curation report: microbial **temperature range mid3**

## Executive conclusion

**Target trait:** **temperature range mid3**  
**Identifier:** **METPO:1000452**  
**Category/kind:** ENVIRONMENT / CLASS  
**Definition supplied for curation:** a growth-supporting ambient-temperature range spanning approximately **30–34 °C**, characteristic of mesophilic physiology.  
**Parent:** **METPO:1000306**  
**Synonyms:** *Mesophilie*; *TR_30_to_34*.

The most defensible causal backbone is **ambient temperature → membrane physical state → membrane-fluidity sensing → fatty-acid remodeling → membrane fluidity compatible with growth**. In *Bacillus subtilis*, the DesK–DesR–des pathway supplies unusually strong molecular evidence for this chain. Recent 2024 lipidomics confirms extensive, but strain-dependent, remodeling of unsaturated fatty acids in *Acinetobacter baumannii*. Chaperone and proteostasis mechanisms are biologically relevant to thermal tolerance, but the retrieved 2024 intervention studies measured survival after severe heat shock rather than sustained growth across a 30–34 °C interval; these edges should therefore remain provisional for this trait. No retrieved study directly demonstrates that a particular molecular perturbation creates the **exact 30–34 °C growth-range breadth**.

## 1. Trait scope and boundary conditions

### 1.1 What the phenotype represents

For TraitMech, **METPO:1000452 should be modeled as an assay-observed thermal niche breadth**, not as a molecular stress response. A positive assignment requires net population growth over a temperature interval whose span falls approximately in the 30–34 °C bin. Suitable endpoints include repeated cell division, increase in viable biomass, specific growth rate, or another validated measure of sustained reproduction.

The phenotype should ideally be represented using cardinal-temperature observations:

- **TMIN:** lowest temperature permitting detectable sustained growth;
- **TOPT:** temperature giving the maximum growth rate under the assay conditions;
- **TMAX:** highest temperature permitting sustained growth;
- **growth-range breadth:** approximately `TMAX − TMIN`, subject to the temperatures actually tested.

A recent adaptive-evolution study explicitly uses TMIN, TMAX, and TOPT to characterize microbial growth profiles and defines mesophiles broadly by **TOPT 20–45 °C**. This broad mesophile definition is not equivalent to a 30–34 °C-wide growth range (lehmann2023adaptivelaboratoryevolution pages 1-2).

### 1.2 Distinctions from neighboring phenotypes

1. **Not temperature optimum.** A microorganism may have TOPT near 30–34 °C but possess a much narrower or wider growth range. Conversely, a 30–34 °C-wide range does not determine where TOPT lies.
2. **Not growth at 30–34 °C.** The supplied definition concerns the *span* of temperatures supporting growth, not merely growth at temperatures numerically between 30 and 34 °C.
3. **Not heat- or cold-shock survival.** Retention of viability after 30 minutes at 55 °C or five days at 52 °C does not establish reproduction at those temperatures or a 30–34 °C growth breadth (liang2024interactionsbetweenchaperone pages 8-10, sato2024effectsofsmall pages 10-11).
4. **Not generic mesophily.** Mesophily is commonly classified by TOPT, whereas this METPO class is a quantitative range bin (lehmann2023adaptivelaboratoryevolution pages 1-2).
5. **Assay dependence is intrinsic.** Medium, pH, oxygen, inoculum history, acclimation, incubation time, and temperature sampling density can alter observed TMIN and TMAX. A coarse temperature grid can over- or underestimate range breadth.

**Recommended graph interpretation:** mechanisms below should be treated as contributors that preserve growth across moderately changing temperatures, not as sufficient determinants of the exact bin.

## 2. Candidate nodes grouped by type

### Trait and experimental nodes

- **temperature range mid3 — METPO:1000452**
- Ambient growth temperature
- Decreased ambient temperature
- Increased ambient temperature
- Temperature shift / cold shock / heat shock
- Sustained growth rate
- TMIN, TOPT, TMAX
- Growth-supporting temperature-range breadth
- Culture medium, oxygen status, pH, acclimation time, and assay duration

### Cellular structures, physical states, and processes

- Cytoplasmic membrane — candidate **GO:0005886**
- Membrane lipid bilayer
- Membrane fluidity
- Membrane lipid order
- Liquid-crystalline membrane state
- Gel-state membrane

Showing the first 60 of 268 lines of findings; the linked file also carries the run's front matter and the prompt it was given — read the full report.