temperature delta mid1

Deep research

Generated by just research-trait; source: research/traits/environment/temperature_delta_mid1-deep-research-falcon.md

# Curation report: temperature delta mid1

## Executive summary

**Trait:** temperature delta mid1  
**Identifier:** **METPO:1000485**  
**Synonym:** Td_10_20  
**Parent:** METPO:1000303  
**Proposed operational meaning:** a microbial strain supports measurable growth over an approximately **10–20 °C interval**, calculated as **Tmax − Tmin**, under one explicitly defined assay condition.

The literature defines thermal tolerance as “the temperature range within which a species can grow.” Accordingly, METPO:1000485 should represent a **growth-range phenotype**, not optimum temperature, environmental temperature at isolation, presence across field samples, or survival after an acute heat/cold shock (he2023highspeciationrate pages 1-2). The strongest general mechanism relevant to the lower end of such a range is homeoviscous membrane adaptation. The strongest upper-end mechanisms are protein-quality-control systems, especially GroEL/GroES and DnaK/DnaJ. However, no located study directly establishes that any single mechanism causes the specific **10–20 °C breadth class**. The final connection from endpoint mechanisms to METPO:1000485 must therefore remain an inferred graph-level hypothesis.

## 1. Trait scope and boundaries

### 1.1 Recommended phenotype definition

For curation, define:

> **temperature delta = highest tested temperature supporting growth − lowest tested temperature supporting growth**, with a value from approximately 10 through 20 °C.

“Growth supporting” should require an assay-level criterion such as a reproducible increase in optical density, biomass, cell count, colony-forming units, or substrate-linked biomass production after inoculation. Record medium, pH, salinity, oxygen status, incubation time, inoculum history, and temperature-step resolution. These variables can move apparent Tmin or Tmax and therefore alter the assigned breadth.

A 2023 hot-spring study treated thermal niche breadth as an occurrence distribution across 54.8–80 °C and classified taxa detected at one temperature as temperature-sensitive and taxa detected at at least five temperatures as resistant/generalist. This is useful ecological evidence, but it is not equivalent to axenic growth limits because abundance, dispersal, interactions, and detection thresholds affect occurrence (he2023highspeciationrate pages 2-4, he2023highspeciationrate pages 1-2).

### 1.2 Boundary cases

- **Narrower neighboring trait:** ΔT below approximately 10 °C; exclude from METPO:1000485.
- **Broader neighboring trait:** ΔT above approximately 20 °C; exclude even if the organism is a mesophile.
- **Endpoint location:** a 10–20 °C breadth can occur around cold, moderate, or warm optima. Breadth does not by itself imply mesophily.
- **Acute survival:** viability after minutes of heat or cold exposure is not growth over the temperature interval.
- **Lag-only response:** transient growth arrest after a temperature shift does not establish a new Tmin or Tmax.
- **Field occupancy:** detection at several environmental temperatures estimates realized niche breadth, not necessarily fundamental growth breadth.
- **Condition-dependent breadth:** oxygen, nutrient composition, salinity, pressure, pH, and host association must be represented as assay or environmental context rather than silently pooled.

### 1.3 Current interpretation

Moderate breadth is best modeled as the intersection of at least two physiological capacities:

1. **Lower-end capacity:** preservation of membrane function, RNA metabolism, translation, and enzyme activity as temperature falls.
2. **Upper-end capacity:** preservation of proteostasis, membrane/envelope integrity, translation, DNA maintenance, and redox homeostasis as temperature rises.

Thermal generalism can also entail a performance trade-off. In hot-spring communities, wide-niche taxa showed niche expansion but poorer local performance—the “jack-of-all-trades, master-of-none” pattern (he2023highspeciationrate pages 1-2). Evolved heat-resistant *E. coli* likewise reached higher maximum temperatures but had decreased fitness at 37 °C (rudolph2010evolutionofescherichia pages 4-5).

## 2. Candidate graph nodes

Identifiers below are conservative suggestions. Label-only nodes are preferable where a strain-specific protein lacks a verified database accession.

### 2.1 Trait and assay nodes

- **temperature delta mid1** — **METPO:1000485**
- temperature delta / growth-temperature breadth — parent supplied as **METPO:1000303**
- minimum growth temperature, Tmin — label-only assay endpoint
- maximum growth temperature, Tmax — label-only assay endpoint
- growth rate, biomass increase, CFU increase — assay-observed variables
- temperature downshift; temperature upshift; chronic growth temperature; acute thermal shock — separate experimental-factor nodes
- culture medium, oxygen availability, salinity, pH, pressure, incubation duration — context nodes

### 2.2 Cellular structures and biophysical states

- cytoplasmic membrane — **GO:0005886**

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