identifier: METPO:1000623
label: moderately halophilic
definition: A halophily preference where growth and proliferation requires high levels
  of sodium chloride, usually above or about 0.2 M.
definition_source: PMID:9758852
trait_category: ENVIRONMENT
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000629
synonyms:
- synonym_text: moderate-halophilic
  synonym_type: RELATED_SYNONYM
  source: metpo.owl
created_by: Anthea Guo
evidence:
- reference: PMID:9758852
  snippet: moderately halophilic bacterium Halomonas elongata
  notes: 'Organism example: Halomonas elongata is described as moderately halophilic.'
canonical_examples:
- taxon_id: NCBITaxon:2746
  taxon_label: Halomonas elongata
  note: "Well-established moderately halophilic gammaproteobacterium (ectoine model; type strain DSM 2581)."
  reference: PMID:20849449
causal_graphs:
- graph_id: moderate_halophile_compatible_solutes
  title: Moderate halophile compatible-solute mechanism
  description: Evidence-backed causal sketch linking moderate halophily to NaCl stress
    and compatible-solute osmoadaptation.
  nodes:
  - node_id: moderately_halophilic_trait
    label: moderately halophilic
    node_type: TRAIT
    grounding: METPO:1000623
    description: Growth requires elevated but not saturated salt concentrations.
  - node_id: elevated_nacl
    label: elevated NaCl
    node_type: ENVIRONMENTAL_FACTOR
    description: Moderate saline growth condition.
  - node_id: osmotic_stress
    label: osmotic stress
    node_type: BIOLOGICAL_PROCESS
    description: Water activity and turgor challenge under saline conditions.
    grounding: GO:0006970
  - node_id: ectoine
    label: ectoine
    node_type: CHEMICAL
    grounding: CHEBI:27500
    description: Compatible solute used by many halophilic bacteria.
  - node_id: glycine_betaine
    label: glycine betaine
    node_type: CHEMICAL
    grounding: CHEBI:17750
    description: Compatible solute transported or accumulated for osmoprotection.
  - node_id: compatible_solute_accumulation
    label: compatible solute accumulation
    node_type: BIOLOGICAL_PROCESS
    description: Intracellular buildup of organic osmolytes for osmoadaptation.
  - node_id: hydroxyectoine
    label: hydroxyectoine
    node_type: CHEMICAL
    description: Hydroxylated derivative of ectoine acting as a compatible solute.
    grounding: CHEBI:49432
  - node_id: ectd
    label: EctD (ectoine hydroxylase)
    node_type: GENE_OR_PROTEIN
    description: Ectoine hydroxylase converting ectoine to hydroxyectoine.
  - node_id: bcct_transporters
    label: BCCT transporters
    node_type: GENE_OR_PROTEIN
    description: Betaine/carnitine/choline transporter family importing compatible
      solutes.
  - node_id: teaabc_transporter
    label: TeaABC TRAP transporter
    node_type: GENE_OR_PROTEIN
    description: TRAP transporter importing ectoine and hydroxyectoine.
  - node_id: salt_out_strategy
    label: salt-out (compatible-solute) strategy
    node_type: BIOLOGICAL_PROCESS
    description: Osmoadaptation strategy relying on accumulation of small organic
      solutes.
  edges:
  - subject: elevated_nacl
    predicate: causes
    object: osmotic_stress
    description: Moderate NaCl elevation imposes osmotic stress that must be balanced
      for growth.
    evidence:
    - reference: DOI:10.1371/journal.pone.0168818
      snippet: cope with high salinities
      notes: Halomonas elongata osmoregulation study supports high salinity as the
        stressor.
    predicate_id: biolink:causes
  - subject: ectoine
    predicate: mitigates
    object: osmotic_stress
    description: Ectoine accumulation helps cells maintain osmotic balance at moderate
      salinity.
    evidence:
    - reference: DOI:10.1371/journal.pone.0168818
      snippet: synthesizes ectoine as its major compatible solute
      notes: Supports ectoine as a compatible-solute mechanism in halophilic bacteria.
    predicate_id: METPO:2007407
  - subject: glycine_betaine
    predicate: mitigates
    object: osmotic_stress
    description: Glycine betaine uptake can contribute to bacterial osmoprotection.
    evidence:
    - reference: DOI:10.1093/femsre/fuy009
      snippet: glycine betaine uptake
      notes: Review supports glycine betaine transport as an osmoadaptation route.
    predicate_id: METPO:2007407
  - subject: ectoine
    predicate: enables
    object: moderately_halophilic_trait
    description: Compatible-solute accumulation supports growth at elevated NaCl.
    evidence:
    - reference: DOI:10.1371/journal.pone.0168818
      snippet: allows microorganisms to cope with high salinities
      notes: Supports compatible solutes as contributors to moderate halophily.
    predicate_id: RO:0002327
  - subject: elevated_nacl
    predicate: selects for
    object: moderately_halophilic_trait
    description: Moderate halophiles grow best under elevated salinity.
    evidence:
    - reference: DOI:10.1093/femsre/fuy009
      snippet: Moderately halophilic bacteria
      notes: Review identifies moderate halophiles as models for bacterial osmotic
        adaptation.
    predicate_id: METPO:2007401
  - subject: osmotic_stress
    predicate: induces
    object: compatible_solute_accumulation
    description: Osmotic stress under elevated NaCl induces accumulation of organic
      compatible solutes.
    evidence:
    - reference: DOI:10.1128/mmbr.62.2.504-544.1998
      notes: 'Ventosa et al. 1998: organic compatible solutes (glycine betaine, ectoine,
        hydroxyectoine, amino acids) predominate in moderate halophiles.'
  - subject: ectd
    predicate: converts
    object: hydroxyectoine
    description: Ectoine hydroxylase EctD converts ectoine to hydroxyectoine, a generic
      ectoine-pathway step across halophiles.
    evidence:
    - reference: DOI:10.1186/s12934-021-01567-6
      notes: 'Liu et al. 2021: EctD is the ectoine hydroxylase converting ectoine
        to hydroxyectoine.'
  - subject: bcct_transporters
    predicate: imports
    object: glycine_betaine
    description: BCCT-family carriers (BetT, BetP, OpuD) import compatible solutes
      such as glycine betaine.
    evidence:
    - reference: DOI:10.58088/07hg-r941
      notes: 'Lichty 2024: BCCT carriers (e.g., BetT, BetP, OpuD) import osmoprotectants.'
    predicate_id: METPO:2000208
  - subject: teaabc_transporter
    predicate: imports
    object: hydroxyectoine
    description: TeaABC TRAP transporter imports ectoine and hydroxyectoine for osmoadaptation.
    evidence:
    - reference: DOI:10.58088/07hg-r941
      notes: 'Lichty 2024: TRAP systems (e.g., TeaABC) import ectoine and 5-hydroxyectoine.'
    predicate_id: METPO:2000208
  - subject: teaabc_transporter
    predicate: imports
    object: ectoine
    description: TeaABC TRAP transporter imports ectoine for osmoadaptation.
    evidence:
    - reference: DOI:10.58088/07hg-r941
      notes: 'Lichty 2024: TRAP systems (e.g., TeaABC) import ectoine and 5-hydroxyectoine.'
    predicate_id: METPO:2000208
  - subject: salt_out_strategy
    predicate: predominates in
    object: moderately_halophilic_trait
    description: The salt-out / compatible-solute strategy predominates among moderate
      halophiles.
    evidence:
    - reference: DOI:10.3389/frmbi.2023.1329925
      notes: 'Ionescu et al. 2024: ''salt-out'' is more common among moderate halophiles
        and relies on accumulation of small organic compounds.'
curation_history:
- timestamp: '2026-05-05T01:35:46.862444+00:00'
  curator: seed_from_metpo
  action: SEEDED_FROM_METPO
  changes: imported from data/raw/metpo.owl (CLASS)
  llm_assisted: false
- timestamp: '2026-05-06T14:15:44-07:00'
  curator: codex
  action: CURATED_WITH_ORGANISM_EXAMPLE
  changes: Added Halomonas elongata organism example with PMID-backed evidence.
  llm_assisted: true
- timestamp: '2026-05-10T00:00:00-07:00'
  curator: codex
  action: ADDED_CAUSAL_GRAPH
  changes: Added DOI-backed causal graph for moderate halophile compatible-solute
    osmoadaptation.
  llm_assisted: true
- timestamp: '2026-05-20T03:35:30Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002327×1).
  llm_assisted: true
- timestamp: '2026-05-20T05:49:24Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (biolink:causes×1).
  llm_assisted: true
- timestamp: '2026-05-23T21:30:06Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 3 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2007407×2, METPO:2007401×1).
  llm_assisted: true
- timestamp: '2026-05-24T04:38:00Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (GO:0006970×1).
  llm_assisted: true
- timestamp: '2026-06-17T04:09:43Z'
  curator: claude
  action: REMOVE_REDUNDANT_SYNONYM
  changes: Removed 1 synonym(s) whose text duplicated the label (seeder redundancy;
    no information lost).
  llm_assisted: true
- timestamp: '2026-06-23T00:00:00Z'
  curator: claude
  action: ENRICH_CAUSAL_GRAPH
  changes: Added 6 evidence-backed generic edges (6 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:10Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 3 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2000208×3).
  llm_assisted: true
- timestamp: '2026-06-24T17:23:30Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (CHEBI:49432×1).
  llm_assisted: true