title: Starch utilization by Bacteroides ovatus isolated from the human large intestine.
abstract: Starch supported growth of continuous cultures of Bacteroides ovatus when this carbohydrate provided the sole source of carbon and energy. Inducible amylase and alpha-glucosidase activities were inversely related to dilution rate in starch-limited and starch-excess chemostats over the dilution rate (D) range D = 0.03/h to D =0.20/h, and were partly repressed during growth under conditions of starch-excess. Preparative isoelectric focusing of B. ovatus cytoplasmic extracts indicated the existence of three distinct starch-hydrolyzing enzymes. Incubation of active fractions from the isoelectric focusing cell with maltose and a variety of low-molecular-weight oligosaccharides (maltotriose, maltotetraose, maltopentaose, maltohexaose, maltoheptaose) identified a single amylase activity, an enzyme with combined beta-amylase and glucoamylase/alpha-glucosidase properties, and also a possible pullulanase. The ability of B. ovatus to synthesize several starch-hydrolyzing enzymes with different specificities and activities may confer a significant competitive advantage to this organism in the colonic ecosystem.
authors.affiliation: Medical Research Council, Dunn Clinical Nutrition Centre, Hills Road, Cambridge CB2 2DH, UK.
authors.forename: B A
authors.initials: BA
authors.lastname: Degnan
authors.forename: S
authors.initials: S
authors.lastname: Macfarlane
authors.forename: M E
authors.initials: ME
authors.lastname: Quigley
authors.forename: G T
authors.initials: GT
authors.lastname: Macfarlane
mesh_terms: D001439:Bacteroides / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism*; D005243:Feces / Q000382:microbiology; D005285:Fermentation; D005087:Glucan 1,4-alpha-Glucosidase / Q000302:isolation & purification / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D007420:Intestine, Large / Q000382:microbiology*; D007525:Isoelectric Focusing; D009844:Oligosaccharides / Q000378:metabolism; D013213:Starch / Q000378:metabolism*; D013379:Substrate Specificity; D000520:alpha-Glucosidases / Q000302:isolation & purification / Q000378:metabolism; D001614:beta-Amylase / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D009844:Oligosaccharides; D013213:Starch; D006026:Glycoside Hydrolases; D001614:beta-Amylase; D000520:alpha-Glucosidases; D005087:Glucan 1,4-alpha-Glucosidase; C100181:pullulanase