identifier: METPO:1000478 label: pH delta high definition: A pH delta phenotype with a growth-supporting pH breadth of approximately 5–9 pH units, characteristic of euryphilic pH-tolerance physiology. definition_source: DOI:10.1038/nrmicro2549 trait_category: ENVIRONMENT term_kind: CLASS mapping_status: REVIEWED parent_traits: - METPO:1000232 synonyms: - synonym_text: pHd_5_9 synonym_type: RELATED_SYNONYM source: metpo.owl evidence: - reference: DOI:10.1038/nrmicro2549 snippet: pH homeostasis notes: pH-homeostasis review supports very broad pH-homeostasis as a hallmark of generalist pH-tolerance physiology. - reference: DOI:10.1016/j.tim.2007.02.005 snippet: proton motive force notes: pH-homeostasis review supports robust proton extrusion and import machinery as the basis of very broad pH-tolerance. causal_graphs: - graph_id: ph_delta_high_euryphilic_breadth title: pH-delta-high euryphilic breadth description: DOI-backed graph linking maximal pH-homeostasis flexibility to a pH growth breadth of approximately 5–9 pH units. nodes: - node_id: ph_delta_high_trait label: pH delta high node_type: TRAIT grounding: METPO:1000478 description: pH growth-supporting breadth approximately 5–9 pH units. - node_id: ph_delta label: pH delta node_type: TRAIT grounding: METPO:1000232 description: Breadth of the growth-supporting external pH range. - node_id: maximal_ph_homeostasis label: maximal pH-homeostasis flexibility node_type: BIOLOGICAL_PROCESS description: Combined proton-extrusion and Na+/H+ antiport flexibility supporting growth across an extreme pH span. - node_id: na_h_antiporters label: Na+/H+ antiporters node_type: GENE_OR_PROTEIN description: Sodium:proton antiporters, core regulators of cytoplasmic pH across changing external pH. - node_id: cytoplasmic_ph_homeostasis label: cytoplasmic pH homeostasis node_type: BIOLOGICAL_PROCESS description: Maintenance of near-neutral internal pH despite external pH variation. grounding: GO:0051453 - node_id: respiratory_proton_pumps label: respiratory proton-pumping enzymes node_type: GENE_OR_PROTEIN description: Electron-transport-chain proton pumps that control proton flux during pH stress. - node_id: f0f1_atpase label: F0F1-ATPase node_type: GENE_OR_PROTEIN description: Proton-translocating ATP synthase contributing to proton extrusion/uptake in pH homeostasis. - node_id: metabolite_decarboxylation label: metabolite decarboxylation pathways node_type: PATHWAY description: Proton-consuming decarboxylation pathways that reduce intracellular acidification. - node_id: cytoplasmic_buffering_capacity label: cytoplasmic buffering capacity node_type: CAPACITY description: Intracellular buffering that limits pH swings in the bacterial cytoplasm. - node_id: near_neutral_cytoplasmic_ph label: near-neutral cytoplasmic pH node_type: QUALITY description: Internal pH maintained near 7.5 while external pH varies. - node_id: growth_external_ph_5_5_9 label: growth across external pH 5.5-9.0 node_type: STATE description: Growth supported across the neutralophile external pH range ~5.5-9.0. - node_id: constant_pmf label: constant proton motive force node_type: BIOLOGICAL_PROCESS description: Relatively constant PMF maintained across external pH changes. - node_id: membrane_lipid_porin_changes label: membrane lipid/porin composition changes node_type: BIOLOGICAL_PROCESS description: Structural changes in membrane lipids and porins during pH stress. - node_id: inward_proton_leakage label: inward proton leakage node_type: BIOLOGICAL_PROCESS description: Passive inward flux of protons that acidifies the cytoplasm. edges: - subject: maximal_ph_homeostasis predicate: produces object: ph_delta_high_trait description: Maximal pH-homeostasis flexibility yields an extreme pH-delta breadth. evidence: - reference: DOI:10.1016/j.tim.2007.02.005 snippet: proton motive force notes: Supports maximal pH-homeostasis flexibility as the basis of euryphilic breadth. predicate_id: METPO:2000202 - subject: ph_delta_high_trait predicate: is a object: ph_delta description: pH delta high is a quantitative bin of the pH-delta phenotype. evidence: - reference: DOI:10.1038/nrmicro2549 snippet: pH homeostasis notes: Supports the 5–9 unit breadth as a value within the pH-delta distribution. predicate_id: rdfs:subClassOf - subject: na_h_antiporters predicate: contributes to object: ph_delta_high_trait description: Na+/H+ antiport is a core regulator of cytoplasmic pH across changing external pH. evidence: - reference: DOI:10.1093/femsre/fuad033 notes: Key regulators of bacterial pH homeostasis are Na+/H+ and K+/H+ antiporters. predicate_id: RO:0002326 - subject: respiratory_proton_pumps predicate: helps maintain object: cytoplasmic_ph_homeostasis description: Electron-transport proton pumps counteract pH stress by controlling proton flux. evidence: - reference: DOI:10.1093/femsre/fuad033 notes: Proton-pumping enzymes (electron transport components) are major homeostasis regulators. - subject: f0f1_atpase predicate: contributes to object: ph_delta_high_trait description: F0F1-ATPase participates in pH homeostasis via proton extrusion or uptake. evidence: - reference: DOI:10.1093/femsre/fuad033 notes: F0F1-ATPase is named among key regulators of bacterial pH homeostasis. predicate_id: RO:0002326 - subject: metabolite_decarboxylation predicate: contributes to object: ph_delta_high_trait description: Proton-consuming decarboxylation pathways support broad pH tolerance. evidence: - reference: DOI:10.1093/femsre/fuad033 notes: Metabolite decarboxylation pathways are key regulators of pH homeostasis. predicate_id: RO:0002326 - subject: cytoplasmic_buffering_capacity predicate: stabilizes object: cytoplasmic_ph_homeostasis description: High buffering capacity limits pH swings, enabling broader pH tolerance. evidence: - reference: DOI:10.1093/femsre/fuad033 notes: Internal pH kept ~7.0-7.5 as buffers absorb fluctuations. - subject: near_neutral_cytoplasmic_ph predicate: enables object: growth_external_ph_5_5_9 description: Neutralophiles maintain narrow internal pH while growing over a broad external range. evidence: - reference: DOI:10.1038/nrmicro2549 notes: Neutralophiles grow at external pH ~5.5-9.0 while maintaining cytoplasmic pH ~7.5-7.7. predicate_id: RO:0002327 - subject: constant_pmf predicate: supports object: ph_delta_high_trait description: A relatively constant PMF across external pH is a hallmark of broad pH tolerance. evidence: - reference: DOI:10.1093/femsre/fuad033 notes: PMF of neutralophilic bacteria kept relatively constant over pH 5 to 8. - subject: membrane_lipid_porin_changes predicate: reduces object: inward_proton_leakage description: Membrane/porin composition changes lower proton leak during acid stress. evidence: - reference: DOI:10.1038/nrmicro2549 notes: Membrane lipid and porin composition changes minimize inward proton leakage during acid stress. predicate_id: METPO:2000017 curation_history: - timestamp: '2026-05-05T01:35:46.840309+00:00' curator: seed_from_metpo action: SEEDED_FROM_METPO changes: imported from data/raw/metpo.owl (CLASS) llm_assisted: false - timestamp: '2026-05-13T10:00:00-07:00' curator: claude action: CURATED_CAUSAL_GRAPH changes: Added DOI-backed definition and causal graph linking maximal pH-homeostasis flexibility to the euryphilic pH-delta-high bin. llm_assisted: true - timestamp: '2026-05-20T03:35:30Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (METPO:2000202×1, rdfs:subClassOf×1). llm_assisted: true - timestamp: '2026-06-23T00:00:00Z' curator: claude action: ENRICH_CAUSAL_GRAPH changes: Added 8 evidence-backed generic edges (11 new nodes) from the deep-research report. llm_assisted: true - timestamp: '2026-06-24T17:21:10Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 5 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002326×3, RO:0002327×1, METPO:2000017×1). llm_assisted: true - timestamp: '2026-06-24T17:21:17Z' curator: claude action: GROUND_CAUSAL_NODES changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (GO:0051453×1). llm_assisted: true