identifier: traitmech:000115
label: starch degradation
definition: A biopolymer-degradation metabolism in which an organism hydrolyzes starch
  (amylose and amylopectin) to maltooligosaccharides and glucose using amylases and
  related glycoside hydrolases.
definition_source: DOI:10.1016/S0168-1656(01)00407-2
trait_category: METABOLISM
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- traitmech:000110
synonyms:
- synonym_text: amylolytic
  synonym_type: RELATED_SYNONYM
  source: DOI:10.1016/S0168-1656(01)00407-2
evidence:
- reference: DOI:10.1016/S0168-1656(01)00407-2
  notes: van der Maarel et al. review starch-converting enzymes of the alpha-amylase
    family that hydrolyze starch to oligosaccharides and glucose.
- reference: DOI:10.1093/nar/gkt1178
  notes: The CAZy database review classifies the glycoside hydrolases (including amylases)
    that microorganisms use to degrade starch and other polysaccharides.
canonical_examples:
- taxon_id: NCBITaxon:1402
  taxon_label: Bacillus licheniformis
  note: "Industrial amylase producer; model for extracellular starch hydrolysis."
  reference: DOI:10.1186/gb-2004-5-10-r77
causal_graphs:
- graph_id: starch_degradation_amylase
  title: Starch degradation hydrolyzes amylose/amylopectin to glucose
  description: Evidence-backed causal sketch linking amylase systems to hydrolysis
    of starch into maltooligosaccharides and glucose.
  nodes:
  - node_id: starch_degradation_trait
    label: starch degradation
    node_type: TRAIT
    grounding: traitmech:000115
    description: Hydrolysis of starch to assimilable sugars.
  - node_id: amylase
    label: amylases / starch-active glycoside hydrolases
    node_type: GENE_OR_PROTEIN
    description: Alpha-amylase family enzymes acting on starch.
  - node_id: glucose
    label: glucose
    node_type: CHEMICAL
    description: Monomeric sugar released from starch hydrolysis.
    grounding: CHEBI:17234
  - node_id: starch
    label: starch (amylose/amylopectin)
    node_type: CHEMICAL
    description: Alpha-glucan polysaccharide substrate of amylolytic degradation.
  - node_id: maltooligosaccharides
    label: maltooligosaccharides
    node_type: CHEMICAL
    description: Short alpha-1,4-linked glucose oligomers released by endo-amylase
      cleavage of starch.
    grounding: CHEBI:17593
  - node_id: alpha_glucosidase
    label: alpha-glucosidase / glucoamylase
    node_type: GENE_OR_PROTEIN
    description: Exo-acting glycoside hydrolase that releases glucose from maltooligosaccharides.
  edges:
  - subject: amylase
    predicate: enables
    object: starch_degradation_trait
    description: Amylases hydrolyze starch's alpha-1,4 and alpha-1,6 linkages.
    evidence:
    - reference: DOI:10.1016/S0168-1656(01)00407-2
      notes: van der Maarel et al. review alpha-amylase-family enzymes that hydrolyze
        starch.
    predicate_id: RO:0002327
  - subject: starch_degradation_trait
    predicate: produces
    object: glucose
    description: Starch hydrolysis yields maltodextrins and glucose.
    evidence:
    - reference: DOI:10.1093/nar/gkt1178
      notes: CAZy review classifies glycoside hydrolases (including amylases) used
        to degrade starch and other polysaccharides.
    predicate_id: METPO:2000202
  - subject: starch
    predicate: is hydrolyzed to
    object: maltooligosaccharides
    description: Endo-amylolytic cleavage of starch yields maltooligosaccharides as
      the core trait-level intermediate.
    evidence:
    - reference: DOI:10.1007/s00018-023-04812-w
      notes: Reports hydrolysis of starch into maltooligosaccharides; flagged as broad
        trait-level core edge across taxa.
  - subject: amylase
    predicate: hydrolyzes
    object: maltooligosaccharides
    description: Alpha-amylase endo-cleaves starch alpha-1,4 bonds to generate maltooligosaccharides.
    evidence:
    - reference: DOI:10.1007/s00018-023-04812-w
      notes: An alpha-amylase hydrolyzes starch into maltooligosaccharides; generic
        alpha-amylase (EC 3.2.1.1) chemistry.
    predicate_id: METPO:2000013
  - subject: alpha_glucosidase
    predicate: degrades
    object: maltooligosaccharides
    description: Alpha-glucosidase/glucoamylase exo-acts on maltooligosaccharides
      to release glucose.
    evidence:
    - reference: DOI:10.1128/mbio.01506-24
      notes: Alpha-glucosidase/glucoamylase degrades maltooligosaccharides to glucose;
        generic terminal exo-hydrolysis step.
    predicate_id: METPO:2000007
  - subject: alpha_glucosidase
    predicate: produces
    object: glucose
    description: Exo-amylolytic release of glucose monomers from maltooligosaccharides.
    evidence:
    - reference: DOI:10.1128/mbio.01506-24
      notes: Alpha-glucosidase/glucoamylase degrades maltooligosaccharides to glucose,
        the terminal assimilable sugar.
    predicate_id: METPO:2000202
curation_history:
- timestamp: '2026-06-08T00:00:00Z'
  curator: claude
  action: PROPOSED_FROM_RESEARCH
  changes: Proposed candidate METABOLISM trait (starch degradation / amylolysis);
    leftover round, sub-variant of biopolymer degradation.
  llm_assisted: true
- timestamp: '2026-06-10T14:00:00Z'
  curator: claude
  action: CURATED_CAUSAL_GRAPH
  changes: Added evidence-backed causal graph (amylase hydrolysis of starch) with
    RO/METPO predicate groundings; promoted PROPOSED to REVIEWED.
  llm_assisted: true
- timestamp: '2026-06-14T06:55:38Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (CHEBI:17234×1).
  llm_assisted: true
- timestamp: '2026-06-23T00:00:00Z'
  curator: claude
  action: ENRICH_CAUSAL_GRAPH
  changes: Added 4 evidence-backed generic edges (3 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:12Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2000202×1).
  llm_assisted: true
- timestamp: '2026-06-24T17:23:33Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (CHEBI:17593×1).
  llm_assisted: true
- timestamp: '2026-06-24T17:23:38Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2000013×1, METPO:2000007×1).
  llm_assisted: true