identifier: traitmech:000006 label: pressure delta definition: A pressure phenotype with numerical limits expressing the breadth (maximum minus minimum) of hydrostatic pressure supporting growth of an organism. definition_source: DOI:10.3389/fmolb.2022.1058381 trait_category: ENVIRONMENT term_kind: CLASS mapping_status: REVIEWED parent_traits: - METPO:1000059 evidence: - reference: DOI:10.3389/fmolb.2022.1058381 snippet: Microorganisms adapted to HHP are usually known as piezophiles, referring to their preference for high pressure notes: Pressure-adaptation review supports the breadth of the pressure-tolerance span as a derived descriptor of pressure-adaptation flexibility. - reference: DOI:10.1099/ijsem.0.001671 snippet: growth range of 80-140 MPa (optimum, 120 MPa) at 6 degrees C notes: The 80-140 MPa span of Colwellia marinimaniae MTCD1 (delta = 60 MPa) illustrates the breadth this phenotype records. causal_graphs: - graph_id: pressure_delta_breadth_descriptor title: 'Pressure delta: breadth of the pressure-tolerance span' description: Evidence-backed sketch linking the hydrostatic-pressure axis to the breadth (max − min) of the growth-supporting pressure range. nodes: - node_id: pressure_delta_trait label: pressure delta node_type: TRAIT grounding: traitmech:000006 description: Breadth (max − min) of the growth-supporting hydrostatic-pressure range. - node_id: hydrostatic_pressure label: hydrostatic pressure node_type: ENVIRONMENTAL_FACTOR description: Ambient hydrostatic pressure imposed on the cell. grounding: PATO:0001025 - node_id: pressure_tolerance_breadth label: pressure-tolerance breadth node_type: QUALITY description: Width of the hydrostatic-pressure interval over which growth is sustained. - node_id: membrane_fluidity_maintenance label: membrane fluidity maintenance under high pressure node_type: BIOLOGICAL_PROCESS description: Maintenance of adequate membrane fluidity against pressure-induced lipid compression. - node_id: membrane_fluidity_loss label: loss of membrane fluidity at high pressure node_type: BIOLOGICAL_PROCESS description: Pressure-induced reduction of membrane fluidity that impairs membrane function. - node_id: unsaturated_fatty_acid_production label: unsaturated fatty acid production node_type: BIOLOGICAL_PROCESS description: Biosynthesis/desaturation generating unsaturated acyl chains that counter pressure-induced membrane ordering. - node_id: ribosome_dissociation label: pressure-induced ribosome dissociation node_type: BIOLOGICAL_PROCESS description: High-pressure dissociation of ribosomes suppressing translation and growth. - node_id: compatible_solutes label: intracellular osmolytes / compatible solutes node_type: CHEMICAL description: Cosolutes/osmolytes that stabilize protein structure under high hydrostatic pressure. - node_id: protein_stabilization_under_pressure label: protein stabilization under pressure node_type: BIOLOGICAL_PROCESS description: Reinforcement of protein structure against pressure-induced perturbation. - node_id: nuo_complex_i label: nuo NADH dehydrogenase I complex node_type: GENE_OR_PROTEIN description: Proton-translocating NADH dehydrogenase I (Complex I) operon enriched in piezophiles. - node_id: high_pressure_energy_conservation label: high-pressure respiratory energy conservation node_type: BIOLOGICAL_PROCESS description: Respiratory-chain energy conservation supporting growth under high hydrostatic pressure. - node_id: min_max_growth_pressure_bounds label: minimum and maximum growth pressure bounds node_type: QUALITY description: Lower and upper hydrostatic-pressure limits of growth whose difference defines the delta. edges: - subject: hydrostatic_pressure predicate: defines object: pressure_delta_trait description: The hydrostatic-pressure axis defines the values whose max minus min yields the delta. evidence: - reference: DOI:10.3389/fmolb.2022.1058381 notes: Pressure-adaptation review frames the breadth of the pressure-tolerance span as a derived descriptor of pressure-adaptation flexibility. predicate_id: METPO:2007500 - subject: pressure_delta_trait predicate: associated with object: pressure_tolerance_breadth description: The delta encodes the breadth of pressure-tolerance flexibility. evidence: - reference: DOI:10.1099/ijsem.0.001671 notes: The 80-140 MPa span of Colwellia marinimaniae MTCD1 (delta = 60 MPa) illustrates the breadth this phenotype records. predicate_id: biolink:associated_with - subject: unsaturated_fatty_acid_production predicate: enables object: membrane_fluidity_maintenance description: Unsaturated acyl-chain production/desaturation sustains membrane fluidity under high hydrostatic pressure. evidence: - reference: DOI:10.1186/s12864-020-07102-y notes: All piezophiles encode a delta-9 acyl-phospholipid desaturase; unsaturated chains allow better adaptation to higher pressures (general HHP mechanism). - reference: DOI:10.1021/acs.chemrev.3c00432 notes: Membrane fluidity adjustment is a core pressure-adaptation node. predicate_id: RO:0002327 - subject: hydrostatic_pressure predicate: causes object: membrane_fluidity_loss description: High hydrostatic pressure compresses membranes and reduces fluidity. evidence: - reference: DOI:10.3389/fmicb.2024.1293928 notes: High pressure causes loss of membrane fluidity (cross-taxa physiological mechanism). predicate_id: biolink:causes - subject: membrane_fluidity_loss predicate: restricts object: pressure_tolerance_breadth description: Loss of membrane fluidity limits growth at the upper pressure bound, narrowing the supported range. evidence: - reference: DOI:10.1038/s43247-023-01045-4 notes: Reduced membrane fluidity under HHP coincides with cessation of respiration/degradation, restricting the upper growth bound. - subject: hydrostatic_pressure predicate: causes object: ribosome_dissociation description: High pressure induces ribosome dissociation, suppressing translation and growth. evidence: - reference: DOI:10.1038/s43247-023-01045-4 notes: High pressure causes ribosome dissociation; translation/replication become dysfunctional, preventing growth and division. predicate_id: biolink:causes - subject: ribosome_dissociation predicate: restricts object: pressure_tolerance_breadth description: Translation failure from ribosome dissociation limits the growth-supporting pressure range. evidence: - reference: DOI:10.1038/s43247-023-01045-4 notes: Ribosome dissociation preventing growth and division narrows the pressure range over which growth is sustained. - subject: compatible_solutes predicate: enables object: protein_stabilization_under_pressure description: Intracellular osmolytes/cosolutes reinforce protein structure under high hydrostatic pressure. evidence: - reference: DOI:10.1021/acs.chemrev.3c00432 notes: Osmolytes reinforce the structure of proteins; cosolutes modulate biomolecular function under HHP (general mechanism). predicate_id: RO:0002327 - subject: nuo_complex_i predicate: supports object: high_pressure_energy_conservation description: The nuo NADH dehydrogenase I complex supports respiratory energy conservation enabling growth under high pressure. evidence: - reference: DOI:10.1186/s12864-020-07102-y notes: nuo dehydrogenase operons present in piezophiles; respiratory-chain composition modulates pressure tolerance, a candidate contributor to wider high-pressure growth support. - subject: min_max_growth_pressure_bounds predicate: defines object: pressure_delta_trait description: The minimum and maximum growth-pressure limits define the breadth (max minus min) recorded by the delta. evidence: - reference: DOI:10.1186/s12864-020-07102-y notes: Range-bound examples (e.g., MTCD1 80-140 MPa => delta = 60 MPa) show min/max bounds defining the pressure-delta breadth descriptor. predicate_id: METPO:2007500 curation_history: - timestamp: '2026-05-28T00:00:00Z' curator: claude action: PROPOSED_FROM_RESEARCH changes: Proposed quantitative companion trait (pressure-tolerance breadth) mirroring the existing temperature_delta / nacl_delta pattern, to fill the pressure coverage gap. llm_assisted: true - timestamp: '2026-06-09T14:00:00Z' curator: claude action: CURATED_CAUSAL_GRAPH changes: Added evidence-backed causal graph (pressure-axis defines tolerance breadth) with METPO/biolink predicate groundings; promoted PROPOSED to REVIEWED. llm_assisted: true - timestamp: '2026-06-16T06:54:39Z' curator: claude action: GROUND_CAUSAL_NODES changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (PATO:0001025×1). llm_assisted: true - timestamp: '2026-06-23T00:00:00Z' curator: claude action: ENRICH_CAUSAL_GRAPH changes: Added 8 evidence-backed generic edges (9 new nodes) from the deep-research report. llm_assisted: true - timestamp: '2026-06-24T17:21:11Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 5 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002327×2, biolink:causes×2, METPO:2007500×1). llm_assisted: true