title: Purification and properties of a beta-1,6-glucanase from Streptomyces sp. EF-14, an actinomycete antagonistic to Phytophthora spp.
abstract: Extracellular enzymes with glucanase activities are an important component of actinomycete-fungus antagonism. Streptomyces sp. EF-14 has been previously identified as one of the most potent antagonists of Phytophthora spp. A beta-1,6-glucanase (EC 3.2.1.75; glucan endo-1,6-beta-glucosidase) was purified by four chromatographic steps from the culture supernatant of strain EF-14 grown on a medium with lyophilized cells of Candida utilis as main nutrient source. The glucanase level in this medium followed a characteristic pattern in which the rise of beta-1,6-glucanase activity always preceded that of beta-1,3-glucanase. The molecular mass of the enzyme was estimated to be 65 kDa and the pI approximately 5.5. It hydrolyzed pustulan by an endo-mechanism generating gentiobiose and glucose as final products. Laminarin was not hydrolyzed indicating that the enzyme does not recognize beta-1,6-links flanked by beta-1,3-links. No significant clearing of yeast cell walls in liquid suspensions or in agar plates was observed indicating that this beta-1,6-glucanase is a non-lytic enzyme. This is the first beta-1,6-glucanase characterized from an actinomycete.
authors.affiliation: Centre d'Etude et de Valorisation de la Diversité Microbienne, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Quebec, Canada.
authors.forename: K P
authors.initials: KP
authors.lastname: Fayad
authors.forename: A M
authors.initials: AM
authors.lastname: Simao-Beaunoir
authors.forename: A
authors.initials: A
authors.lastname: Gauthier
authors.forename: C
authors.initials: C
authors.lastname: Leclerc
authors.forename: H
authors.initials: H
authors.lastname: Mamady
authors.forename: C
authors.initials: C
authors.lastname: Beaulieu
authors.forename: R
authors.initials: R
authors.lastname: Brzezinski
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D002855:Chromatography, Thin Layer; D006026:Glycoside Hydrolases / Q000302:isolation & purification* / Q000378:metabolism; D010838:Phytophthora / Q000382:microbiology*; D013302:Streptomyces / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D006026:Glycoside Hydrolases; C020105:endo-1,6-beta-glucanase