identifier: METPO:1000625
label: slightly halophilic
definition: A halophily preference in which an organism requires low to moderate salt
  concentrations (0.3 to 0.8 M NaCl) for optimal growth.
definition_source: PMID:12501437
trait_category: ENVIRONMENT
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000629
evidence:
- reference: PMID:12501437
  snippet: A slightly halophilic, extremely halotolerant, alkaliphilic
  notes: 'Organism example: Paraliobacillus ryukyuensis strain O15-7T is described
    as slightly halophilic.'
causal_graphs:
- graph_id: slight_halophile_low_salt_osmoadaptation
  title: Slight halophile low-salt osmoadaptation mechanism
  description: Evidence-backed causal sketch linking slight halophily to low or moderate
    NaCl and compatible-solute osmoprotection.
  nodes:
  - node_id: slightly_halophilic_trait
    label: slightly halophilic
    node_type: TRAIT
    grounding: METPO:1000625
    description: Optimal growth requires low to moderate salt concentrations.
  - node_id: low_moderate_nacl
    label: low to moderate NaCl
    node_type: ENVIRONMENTAL_FACTOR
    description: Salinity range below that of moderate and extreme halophiles.
  - node_id: osmotic_stress
    label: osmotic stress
    node_type: BIOLOGICAL_PROCESS
    description: Osmotic challenge caused by environmental salt.
    grounding: GO:0006970
  - node_id: compatible_solutes
    label: compatible solutes
    node_type: CHEMICAL
    description: Organic osmoprotectants accumulated or synthesized in response to
      salt.
    grounding: CHEBI:25728
  - node_id: osmoprotectant_transport
    label: osmoprotectant transport
    node_type: MOLECULAR_FUNCTION
    description: Uptake of compatible solutes such as glycine betaine.
  - node_id: salt_tolerance
    label: salt tolerance
    node_type: CAPACITY
    description: Capacity to grow and survive under elevated salinity / salt stress.
  - node_id: ectoine_biosynthesis
    label: ectoine biosynthesis
    node_type: BIOLOGICAL_PROCESS
    description: Biosynthesis of the compatible solute ectoine via the ectABC/ectBACD
      pathway.
    grounding: GO:0019491
  - node_id: ect_gene_cluster
    label: ectABC/ectBACD gene cluster
    node_type: GENE_OR_PROTEIN
    description: Ectoine biosynthesis operon encoding the ectoine pathway enzymes.
  - node_id: ectoine
    label: ectoine
    node_type: CHEMICAL
    description: A major compatible solute (osmolyte) accumulated under salt stress.
    grounding: CHEBI:27592
  - node_id: ion_homeostasis
    label: ion homeostasis during salt stress
    node_type: BIOLOGICAL_PROCESS
    description: Maintenance of Na+/K+ balance under salt stress.
  - node_id: na_k_transcription
    label: Na+/K+ transcriptional induction
    node_type: BIOLOGICAL_PROCESS
    description: Coordinated induction of sodium/potassium transport transcription
      under salt stress.
  edges:
  - subject: low_moderate_nacl
    predicate: enables
    object: slightly_halophilic_trait
    description: Slight halophily is a salt-growth preference at lower salinity than
      moderate or extreme halophily.
    evidence:
    - reference: DOI:10.1186/1746-1448-4-2
      snippet: minimum salt concentration required for growth
      notes: Review supports halophily as a continuum of salt growth requirements.
    predicate_id: RO:0002327
  - subject: low_moderate_nacl
    predicate: causes
    object: osmotic_stress
    description: Even lower salinity preferences involve osmotic adjustment to environmental
      salt.
    evidence:
    - reference: DOI:10.1186/1746-1448-4-2
      snippet: salt relationships
      notes: Review describes growth in relation to minimum, optimum, and upper salt
        limits.
    predicate_id: biolink:causes
  - subject: compatible_solutes
    predicate: mitigates
    object: osmotic_stress
    description: Compatible solutes provide osmotic balance without disrupting metabolism.
    evidence:
    - reference: DOI:10.1371/journal.pone.0168818
      snippet: do not disturb the cell's metabolism
      notes: Supports compatible solutes as non-disruptive osmoprotectants.
    predicate_id: METPO:2007407
  - subject: osmoprotectant_transport
    predicate: accumulates
    object: compatible_solutes
    description: Uptake systems can accumulate compatible solutes for salt adaptation.
    evidence:
    - reference: DOI:10.1093/femsre/fuy009
      snippet: organic osmotic solutes
      notes: Review supports accumulation of organic osmotic solutes in bacterial
        osmoadaptation.
    predicate_id: METPO:2000210
  - subject: ect_gene_cluster
    predicate: enables
    object: ectoine_biosynthesis
    description: The ect gene cluster encodes the enzymes that carry out ectoine biosynthesis.
    evidence:
    - reference: DOI:10.1128/aem.01905-23
      notes: ectoine biosynthesis genes are denoted by ectABC; ectBACD up-regulated
        as an osmoadaptation system.
    predicate_id: RO:0002327
  - subject: ectoine_biosynthesis
    predicate: produces
    object: ectoine
    description: Ectoine biosynthesis produces the compatible solute ectoine.
    evidence:
    - reference: DOI:10.1128/aem.01905-23
      notes: Wild-type accumulates ectoine as its major osmolyte via the ectABC pathway.
    predicate_id: METPO:2000202
  - subject: ectoine
    predicate: increases
    object: salt_tolerance
    description: Accumulation of ectoine as a compatible solute increases salt tolerance.
    evidence:
    - reference: DOI:10.1128/aem.01905-23
      notes: Wild-type accumulates ectoine as its major osmolyte while the ectABC-deleted
        strain is salt-sensitive.
    predicate_id: RO:0002213
  - subject: osmoprotectant_transport
    predicate: increases
    object: salt_tolerance
    description: Uptake of compatible solutes is a general salt-out osmoadaptation
      strategy that raises salt tolerance.
    evidence:
    - reference: DOI:10.1093/femsre/fuy026
      notes: Salt-out strategists exclude salt and/or synthesize or uptake compatible
        solutes (e.g. glycine betaine); dominant strategy in many halophilic bacteria.
    predicate_id: RO:0002213
  - subject: na_k_transcription
    predicate: supports
    object: ion_homeostasis
    description: Coordinated induction of Na+/K+ transcription supports ion homeostasis
      during salt stress.
    evidence:
    - reference: DOI:10.1038/s42003-022-04319-3
      notes: Coordinated induction of Na+/K+ transcription and ectoine, proline, and
        betaine biosynthesis under salt stress.
curation_history:
- timestamp: '2026-05-05T01:35:46.863572+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 Paraliobacillus ryukyuensis 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 slight halophile compatible-solute osmoadaptation.
  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 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2007407×1).
  llm_assisted: true
- timestamp: '2026-05-24T04:13:18Z'
  curator: claude
  action: RENAME_PREDICATE_LABELS
  changes: 'Renamed 1 causal-edge predicate label(s) to align with existing groundings:
    supports → enables ×1.'
  llm_assisted: true
- timestamp: '2026-05-24T04:13:21Z'
  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: '2026-05-24T04:38:00Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 2 causal-node grounding field(s) via mappings/node_grounding.tsv
    (GO:0006970×1, CHEBI:65015×1).
  llm_assisted: true
- timestamp: '2026-06-15T07:19:08Z'
  curator: claude
  action: FIX_NODE_GROUNDING_CURIE
  changes: Overwrote 1 causal-node grounding(s) to corrected CURIEs (phase-2 id-label
    fix; verified vs OAK).
  llm_assisted: true
- timestamp: '2026-06-16T06:30:56Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2000210×1).
  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 5 evidence-backed generic edges (6 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:11Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 4 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002213×2, RO:0002327×1, METPO:2000202×1).
  llm_assisted: true
- timestamp: '2026-06-24T17:23:31Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 2 causal-node grounding field(s) via mappings/node_grounding.tsv
    (GO:0019491×1, CHEBI:27592×1).
  llm_assisted: true