identifier: METPO:1000609
label: aerotolerant
definition: An oxygen preference that does not use O₂ for growth but tolerates its
  presence.
definition_source: https://bio.libretexts.org/Courses/Ohio_State_University/Microbiology_Lab_SP25/05%3A_Lab_5/5.05%3A_Bacterial_Oxygen_Requirements
trait_category: ENVIRONMENT
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000601
synonyms:
- synonym_text: aerotolerant anaerobe
  synonym_type: RELATED_SYNONYM
  source: https://bio.libretexts.org/Courses/Ohio_State_University/Microbiology_Lab_SP25/05%3A_Lab_5/5.05%3A_Bacterial_Oxygen_Requirements
evidence:
- reference: https://bio.libretexts.org/Courses/Ohio_State_University/Microbiology_Lab_SP25/05%3A_Lab_5/5.05%3A_Bacterial_Oxygen_Requirements
  snippet: they do not utilize it for ATP production
  notes: Supports aerotolerance as oxygen tolerance without oxygen use.
- reference: PMID:38864615
  snippet: this bacterium is relatively aerotolerant and survives limited oxygen exposure
  notes: 'Organism example: Clostridium perfringens is described as aerotolerant.'
canonical_examples:
- taxon_id: NCBITaxon:1358
  taxon_label: Lactococcus lactis
  note: "aerotolerant fermenter"
  reference: PMID:11443085
- taxon_id: NCBITaxon:1314
  taxon_label: Streptococcus pyogenes
  note: "aerotolerant anaerobe"
  reference: PMID:10986229
causal_graphs:
- graph_id: aerotolerant_anaerobe_ros_defense
  title: Aerotolerant anaerobe ROS-defense mechanism
  description: Evidence-backed causal sketch linking aerotolerance to anaerobic growth
    plus enzymatic defenses against oxygen-derived stress.
  nodes:
  - node_id: aerotolerant_trait
    label: aerotolerant
    node_type: TRAIT
    grounding: METPO:1000609
    description: Does not use oxygen for growth but tolerates its presence.
  - node_id: molecular_oxygen
    label: molecular oxygen
    node_type: CHEMICAL
    grounding: CHEBI:15379
    description: Dioxygen exposure tolerated by aerotolerant anaerobes.
  - node_id: reactive_oxygen_species
    label: reactive oxygen species
    node_type: CHEMICAL
    grounding: CHEBI:26523
    description: Oxygen-derived oxidants that can damage cells.
  - node_id: superoxide_dismutase
    label: superoxide dismutase
    node_type: GENE_OR_PROTEIN
    description: Enzyme associated with detoxification of superoxide stress.
    grounding: UniProtKB:A0A009QPW9
  - node_id: anaerobic_growth
    label: anaerobic growth
    node_type: BIOLOGICAL_PROCESS
    description: Growth supported without using oxygen as an energy substrate.
  - node_id: hydrogen_peroxide
    label: hydrogen peroxide
    node_type: CHEMICAL
    description: Reactive oxygen species produced during oxygen exposure that damages
      cells.
    grounding: CHEBI:16240
  - node_id: hydrogen_peroxide_detoxification
    label: hydrogen peroxide detoxification
    node_type: BIOLOGICAL_PROCESS
    description: Enzymatic removal of hydrogen peroxide to limit oxidative damage.
    grounding: GO:0033355
  - node_id: catalase
    label: catalase
    node_type: GENE_OR_PROTEIN
    description: Enzyme that degrades hydrogen peroxide rapidly at higher concentrations.
    grounding: UniProtKB:A0A071MK53
  - node_id: rubrerythrin
    label: rubrerythrin
    node_type: GENE_OR_PROTEIN
    description: Non-heme iron protein that scavenges low levels of hydrogen peroxide.
    grounding: UniProtKB:A0A016EEI2
  - node_id: nadh_peroxidase
    label: NADH peroxidase
    node_type: GENE_OR_PROTEIN
    description: Enzyme reducing hydrogen peroxide to water using NADH.
    grounding: UniProtKB:A0A031WCC0
  - node_id: nadph_peroxidase
    label: NADPH peroxidase
    node_type: GENE_OR_PROTEIN
    description: Enzyme reducing hydrogen peroxide to water using NADPH.
  edges:
  - subject: aerotolerant_trait
    predicate: includes
    object: anaerobic_growth
    description: Aerotolerant anaerobes grow anaerobically while tolerating oxygen.
    evidence:
    - reference: DOI:10.1038/nrmicro2970
      snippet: Aerotolerant anaerobes ... ROS defence ... Anaerobic growth
      notes: Table classifies aerotolerant anaerobes as anaerobic-growth organisms
        with ROS defence.
    predicate_id: biolink:has_part
  - subject: molecular_oxygen
    predicate: can generate
    object: reactive_oxygen_species
    description: Oxygen exposure creates ROS stress that aerotolerant organisms must
      defend against.
    evidence:
    - reference: DOI:10.1038/s41579-021-00583-y
      snippet: molecular oxygen and ROS
      notes: Review links oxygen exposure and reactive oxygen species in anaerobes.
  - subject: superoxide_dismutase
    predicate: contributes to
    object: aerotolerant_trait
    description: Superoxide dismutase abundance is associated with oxygen tolerance
      among anaerobic bacteria.
    evidence:
    - reference: DOI:10.1128/iai.16.1.20-25.1977
      snippet: aerotolerant and intermediate organisms had SOD
      notes: Comparative anaerobe study supports SOD as an oxygen-tolerance factor.
    predicate_id: RO:0002326
  - subject: superoxide_dismutase
    predicate: mitigates
    object: reactive_oxygen_species
    description: SOD mitigates superoxide stress generated during oxygen exposure.
    evidence:
    - reference: DOI:10.1128/iai.16.1.20-25.1977
      snippet: oxygen tolerance of anaerobes is usually related to their level of
        SOD
      notes: Supports SOD as a ROS-defense mechanism for aerotolerant anaerobes.
    predicate_id: METPO:2007407
  - subject: catalase
    predicate: enables
    object: hydrogen_peroxide_detoxification
    description: Catalase degrades hydrogen peroxide, enabling its detoxification.
    evidence:
    - reference: DOI:10.1038/s43705-023-00251-7
      notes: catalase degrades H2O2 rapidly at higher concentrations
    predicate_id: RO:0002327
  - subject: rubrerythrin
    predicate: decreases
    object: hydrogen_peroxide
    description: Rubrerythrin scavenges low levels of hydrogen peroxide.
    evidence:
    - reference: DOI:10.1038/s43705-023-00251-7
      notes: rubrerythrins scavenge low H2O2 levels
    predicate_id: RO:0002212
  - subject: nadh_peroxidase
    predicate: decreases
    object: hydrogen_peroxide
    description: NADH peroxidase reduces hydrogen peroxide to water.
    evidence:
    - reference: DOI:10.1038/s41598-023-41185-3
      notes: NADH + H+ + H2O2 reversible to NAD+ + 2 H2O
    predicate_id: RO:0002212
  - subject: nadph_peroxidase
    predicate: decreases
    object: hydrogen_peroxide
    description: NADPH peroxidase reduces hydrogen peroxide to water.
    evidence:
    - reference: DOI:10.1038/s41598-023-41185-3
      notes: an analogous NADPH peroxidase produces NADP+
    predicate_id: RO:0002212
curation_history:
- timestamp: '2026-05-05T01:35:46.853836+00:00'
  curator: seed_from_metpo
  action: SEEDED_FROM_METPO
  changes: imported from data/raw/metpo.owl (CLASS)
  llm_assisted: false
- timestamp: '2026-05-05T01:09:05-07:00'
  curator: codex
  action: CURATED_WITH_LITERATURE
  changes: Added definition source, supported synonym, and evidence for aerotolerance.
  llm_assisted: true
- timestamp: '2026-05-05T18:39:46-07:00'
  curator: codex
  action: ADDED_ORGANISM_EXAMPLE
  changes: Added Clostridium perfringens 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 aerotolerance and ROS-defense mechanisms
    in anaerobes.
  llm_assisted: true
- timestamp: '2026-05-20T03:35:29Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002326×1).
  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: '2026-05-24T05:05:13Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (UniProtKB:A0A009QPW9×1).
  llm_assisted: true
- timestamp: '2026-06-13T21:03:25Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (biolink:has_part×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 4 evidence-backed generic edges (6 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:09Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 4 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002212×3, RO:0002327×1).
  llm_assisted: true
- timestamp: '2026-06-24T17:21:16Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (UniProtKB:A0A071MK53×1).
  llm_assisted: true
- timestamp: '2026-06-24T17:23:30Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 2 causal-node grounding field(s) via mappings/node_grounding.tsv
    (CHEBI:16240×1, GO:0033355×1).
  llm_assisted: true
- timestamp: '2026-06-26T07:15:17Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 2 causal-node grounding field(s) via mappings/node_grounding.tsv
    (UniProtKB:A0A016EEI2×1, UniProtKB:A0A031WCC0×1).
  llm_assisted: true