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temperature range very low

METPO:1000448 · CLASS · REVIEWED

A temperature range phenotype in which growth extends to ambient temperatures at or below approximately 10 °C, characteristic of psychrophilic growth ranges.

Trait evidence (1)

  • DOI:10.1038/sj.embor.7400662
    growing well at temperatures around the freezing point of water

    Psychrophile review supports growth at very low temperatures as the psychrophilic range.

Temperature-range-very-low psychrophile context

DOI-backed nonmechanistic graph connecting membrane desaturation, two-component cold signaling, CspA-family RNA chaperones, cold proteostasis, compatible-solute stabilization, and ice-binding protein branches to the at-or-below-10-degrees-C growth-range 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-range-very-low psychrophile context Interactive directed graph showing evidence-backed causal relationships for temperature range very low.

Edge evidence

  • psychrophile cold-adapted machinery confers temperature range very low METPO:2007700

    Psychrophile cold-adapted machinery enables growth at ≤ 10 °C.

    • DOI:10.1038/sj.embor.7400662 decreased membrane fluidity Supports cold-adapted membranes and enzymes as enablers of growth at very low temperatures.
  • temperature range very low is a temperature range rdfs:subClassOf

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

    • DOI:10.1038/sj.embor.7400662 growing well at temperatures around the freezing point of water Supports a ≤10 °C range as a value within the temperature-range distribution.
  • membrane fatty-acid desaturation increases membrane fluidity RO:0002213

    Homeoviscous adaptation via lipid desaturation maintains membrane fluidity in the cold.

    • DOI:10.1007/s42770-023-01057-4 production of double bonds in lipids Verified against the open Ramón et al. PubMed abstract; the multifactorial cold-adaptation model lists membrane composition adaptation by producing lipid double bonds.
  • low temperature activates two-component cold signaling RO:0002213

    Cold-induced membrane state changes activate two-component cold signaling.

    • DOI:10.1007/s42770-023-01057-4 activation of a two-component system Verified against the open Ramón et al. PubMed abstract; cold sensing is described as occurring mainly through liquid-crystalline membrane-state changes that activate a two-component signal-transduction system.
  • cold-shock proteins (CspA-family) regulates cold-stabilized mRNA/RNA secondary structure RO:0002211

    CspA-family RNA chaperones regulate cold-stabilized RNA structures to sustain translation.

    • DOI:10.4161/rna.7.6.13482 through their RNA chaperoning function Verified against the open Phadtare and Severinov PubMed abstract; CspA-family cold-shock proteins are described as RNA-modulating proteins affecting low-temperature transcription and possibly translation through RNA chaperoning.
  • molecular chaperones (DnaK/GroEL/GroES/Clp/TF) contributes to protein folding and proteostasis in the cold RO:0002326

    Chaperone/protease systems contribute to proteostasis by countering cold-slowed folding and misfolding risk.

    • DOI:10.3389/fmicb.2023.1197797 heat shock proteins associated to folding Verified against the open Ramasamy et al. PMC text; the Antarctic psychrophile review discusses heat-shock proteins associated with protein folding in 4 °C versus 18 °C Pseudoalteromonas haloplanktis TAC125.
  • compatible solutes (glycine betaine/trehalose/glycerol) contributes to protein and membrane stabilization RO:0002326

    Osmolytes contribute to protein and membrane stabilization while lowering freezing damage.

    • DOI:10.3389/fmicb.2023.1197797 counteracting protein aggregation, improving protein folding Verified against the open Ramasamy et al. PMC text; Antarctic compatible osmolytes are described as counteracting protein aggregation and improving protein folding.
  • ice-binding/antifreeze proteins inhibits ice-crystal growth/recrystallization RO:0002212

    AFPs/IBPs bind ice and inhibit ice-crystal growth and recrystallization.

    • DOI:10.3389/fmicb.2023.1197797 inhibits the growth of ice crystals Verified against the open Ramasamy et al. PMC text; ice binding proteins are described as antifreeze proteins that bind ice, inhibit ice-crystal growth, lower freezing temperature, create a thermal hysteresis gap, and display ice-recrystallization inhibition activity.
  • membrane fluidity associated with psychrophile cold-adapted machinery biolink:associated_with

    Membrane fatty-acid desaturation is associated with the cold-adapted machinery supporting psychrophile growth ranges.

    • DOI:10.1007/s42770-023-01057-4 maintain the liquid crystalline phase Verified against the open Ramón et al. PubMed abstract; this connector keeps membrane desaturation as cold membrane-adaptation context.
  • two-component cold signaling associated with psychrophile cold-adapted machinery biolink:associated_with

    Two-component cold signaling is associated with psychrophile cold-adapted machinery.

    • DOI:10.1007/s42770-023-01057-4 When the temperature drops, DesK/DesR is the two-component system involved in membrane adaptation Verified against the open Ramón et al. PubMed abstract; this connector keeps low-temperature membrane sensing as cold-acclimation context.
  • cold-stabilized mRNA/RNA secondary structure associated with psychrophile cold-adapted machinery biolink:associated_with

    CspA-family regulation of cold-stabilized RNA structure is associated with psychrophile cold-adapted machinery.

    • DOI:10.4161/rna.7.6.13482 CspA, the main cold shock protein, and its homologs act as RNA chaperones Verified against the open Phadtare and Severinov PubMed abstract; this connector keeps CspA-family RNA chaperones as low-temperature transcript context.
  • protein folding and proteostasis in the cold associated with psychrophile cold-adapted machinery biolink:associated_with

    Cold proteostasis support is associated with the psychrophile machinery context.

    • DOI:10.3389/fmicb.2023.1197797 ice binding, cold shock and heat shock proteins to sustain their physiological state Verified against the open Ramasamy et al. PMC text; this connector keeps chaperone/protease systems as protein-folding context.
  • protein and membrane stabilization associated with psychrophile cold-adapted machinery biolink:associated_with

    Compatible-solute stabilization is associated with psychrophile cold-adapted machinery.

    • DOI:10.3389/fmicb.2023.1197797 scavenging free radicals, counteracting protein aggregation Verified against the open Ramasamy et al. PMC text; this connector keeps compatible osmolytes as stabilization context.
  • ice-crystal growth/recrystallization associated with psychrophile cold-adapted machinery biolink:associated_with

    Ice-binding protein inhibition of ice-crystal growth is associated with psychrophile cold-adapted machinery.

    • DOI:10.3389/fmicb.2023.1197797 This ceases ice growth by creating a thermal hysteresis gap Verified against the open Ramasamy et al. PMC text; this connector keeps ice-binding proteins as freezing-protection context.

Provenance

Identifier source
METPO (2026-06-12)
Definition source
DOI:10.1038/sj.embor.7400662

Parent traits (1)

Synonyms (2)

  • Psychrophile EXACT_SYNONYM · metpo.owl
  • TR_<=10 RELATED_SYNONYM · metpo.owl

kg-microbe context

Matched 1 kg-microbe node via direct_metpo.

  • METPO:1000448 [-3.031, -0.161, -1.423, +4.596, …]

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_very_low-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 very-low-temperature growth

## Trait record and scope

- **Trait:** temperature range very low
- **Identifier:** **`METPO:1000448`**
- **Category / kind / status:** ENVIRONMENT / CLASS / REVIEWED
- **Parent:** `METPO:1000306`
- **Operational interpretation:** a growth-temperature-range phenotype in which **reproducible population growth extends to ≤10 °C**. The decisive observation should be biomass, viable-cell number, growth rate, or repeated division—not respiration alone, survival after cold shock, or activity of an isolated enzyme.

This operational scope is broader than the classical definition of an obligate or strict psychrophile. Traditional definitions generally require growth near 0 °C, an optimum around or below 15 °C, and an upper limit near 20 °C; psychrotrophs/psychrotolerant organisms also grow in the cold but have substantially higher optima or maxima. Recent reviews continue to use somewhat inconsistent numerical boundaries, making the measured growth range more reliable than the label “psychrophile.” (moyer2017psychrophilesandpsychrotrophs pages 2-3, purwar2024adaptationsofpsychrophilic pages 1-3, ramon2023ageneraloverview pages 1-2)

### Boundary cases

1. **Include:** sustained growth at 10, 4, 0, or subzero temperature, even where the organism's optimum is above 15 °C. Pseudoalteromonas sp. WY3, for example, grew at 4 °C but had predicted `Topt = 24.8 °C`; it therefore supports `METPO:1000448` under the supplied range definition but is not a classical strict psychrophile. Its measured rates were 0.0011, 0.0021, 0.0449, 0.1428, and 0.1478 h⁻¹ at 4, 8, 12, 16, and 25 °C, respectively; predicted `Tmin`, `Topt`, and `Tmax` were −1.2, 24.8, and 36.5 °C. (wang2024genomicinsightsinto pages 11-12)
2. **Exclude:** survival at −30 °C without demonstrated division; metabolic activity inferred at −40 °C; a transient cold-shock response followed by no growth; or an isolated cold-active enzyme. Reviews explicitly distinguish verified growth down to approximately −15 °C from survival or predicted metabolism at lower temperatures. (moyer2017psychrophilesandpsychrotrophs pages 2-3)
3. **Do not infer from habitat:** isolation from glacier, permafrost, Antarctic soil, refrigerated food, or deep ocean is insufficient without a growth assay.
4. **Do not infer strict psychrophily from ≤10 °C growth alone:** record optimum and maximum temperatures separately where available. Pseudarthrobacter psychrotolerans YJ56 grew best at 13 °C and failed to grow at 30 °C, which is much stronger evidence of a genuinely cold-adapted range than growth at 4 °C alone. (son2023morphologicalandphysiological pages 1-2)
5. **Separate acute and acclimated states:** cold shock, acclimation, and steady-state cold growth can activate different systems. A 2023 study deliberately compared sustained growth at 0 and 15 °C rather than an acute shock and found extensive transcriptional remodeling despite a comparatively stable central metabolome. (riccardi2023metabolicrobustnessto pages 1-2)

## Current mechanistic model

Very-low-temperature growth is a systems phenotype rather than a single pathway. Cooling rigidifies membranes, stabilizes inhibitory RNA structures, slows enzyme catalysis and macromolecular turnover, perturbs protein folding, raises oxidative stress through greater oxygen solubility, and can impose freeze-concentration/osmotic stress. Successful organisms combine homeoviscous membrane remodeling, RNA and ribosome maintenance, protein-quality control, cold-active catalysis, redox protection, compatible-solute/EPS production, and regulatory or metabolic buffering. Recent authoritative analysis emphasizes that the exact combination is strongly taxon- and temperature-transition-specific. (bao2023miningofkey pages 1-2, ramon2023ageneraloverview pages 1-2, riccardi2023metabolicrobustnessto pages 1-2)

## Candidate nodes grouped by type

### Phenotype, environment, and assay nodes

- `METPO:1000448` — temperature range very low.
- Low growth temperature: **10, 4, 0, or subzero °C**; retain the exact assay temperature as evidence metadata.
- Sustained low-temperature population growth; growth rate; lag duration; biomass/OD; viable count.
- Cold shock, cold acclimation, and steady-state cold growth as separate experimental-condition nodes.
- Freeze–thaw exposure and extracellular ice as separate stressors, not synonyms of low-temperature growth.
- Candidate environments: glacier ice, permafrost, Antarctic marine water, Antarctic soil, and refrigerated environments. Assign ENVO CURIEs only after checking the exact sampled habitat.

### Cellular structures and processes

- Cell membrane / plasma membrane — **GO:0005886**.
- Membrane lipid remodeling and homeoviscous adaptation — label-only pending exact ontology review.
- Membrane fluidity, permeability, and transport competence.
- Ribosome — **GO:0005840**; 50S ribosomal subunit — **GO:0005842**.
- Translation — **GO:0006412**; protein folding — **GO:0006457**.
- RNA secondary-structure remodeling / RNA helicase activity.
- Cell wall remodeling; peptidoglycan turnover.
- Oxidative-stress response — **GO:0006979**.
- Biofilm formation — **GO:0042710**.
- Central-carbon metabolic homeostasis and transcriptomic buffering.

### Genes, proteins, enzymes, and complexes

**Higher-priority, functionally supported candidates**

- **csdA**: cold-associated DEAD-box RNA helicase; knockout reduces low-temperature growth in Psychrobacter arcticus 273-4.
- **relA**: stringent-response enzyme; knockout reduces low-temperature growth in the same strain.
- **dac2**: cold-upregulated DD-peptidase/carboxypeptidase; knockout reduces low-temperature growth.
- **GroEL**: chaperonin; heterologous expression of the Rhodococcus sp. RCBS9 protein improved E. coli growth at 10 °C.
- **Dps**: DNA-binding ferritin-like stress protein; RCBS9 Dps expression improved E. coli growth at 10 °C.
- **USP-2**: universal stress protein; RCBS9 USP-2 expression improved E. coli growth at 10 °C.

**Mechanistically plausible but mostly expression/genomic-association candidates**

Showing the first 60 of 217 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.

  • Psychromonas ingrahamii NCBITaxon:357794 DOI:10.1099/ijs.0.64068-0 Psychromonas ingrahamii strain 37T grew from -12 to 10 degrees C in its primary species description, directly establishing growth at and below this bin's 10-degree threshold.

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 psychrophile cold-adapted machinery to the temperature-range-very-low 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 6 evidence-backed generic edges (12 new nodes) from the deep-research report.

  5. · GROUND_CAUSAL_PREDICATES · claude

    Grounded 3 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002213×2, RO:0002212×1).

  6. · GROUND_CAUSAL_NODES · claude

    Grounded 2 causal-node grounding field(s) via mappings/node_grounding.tsv (PATO:0001306×1, 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_very_low_psychrophile=NONMECHANISTIC with scope_notes; marked 3 GENE_OR_PROTEIN node(s) REVIEWED_LABEL_ONLY with grounding_notes (cold_shock_proteins, molecular_chaperones, ice_binding_proteins).

  9. · ADD_CANONICAL_EXAMPLES · codex

    Resolved issue #444 after the #591 source/bin policy with 1 direct source-backed canonical example(s): Psychromonas ingrahamii (NCBITaxon:357794; DOI:10.1099/ijs.0.64068-0). The note retains the measured value or scopes broad-class examples to the cited branch; no paid research was used.

  10. · REVIEW_CAUSAL_EVIDENCE · codex

    Reviewed the temperature_range_very_low_psychrophile graph for issue #183: added snippets to 6 edge-level evidence items, grounded 3 residual predicates, and narrowed 1 local node identifier and type for cold-stabilized RNA secondary structure. No paid research service was called.

  11. · CONNECT_CAUSAL_GRAPH_COMPONENTS · codex

    Resolved issue #183 graph fragmentation (7 components to 1) by adding 6 source- and verbatim-snippet-backed association connectors among membrane desaturation, two-component cold signaling, CspA-family RNA chaperone, cold proteostasis, compatible-solute, and ice-binding protein branches. No paid research service was called.

  12. · ADVERSARIAL_REVIEW_REPAIR · codex

    Addressed PR #664 adversarial review: replaced copied Ramasamy cold-adaptation snippets with independent exact text supporting compatible-osmolyte and ice-binding-protein context edges.