title: Characterization of β-glucosidase produced by the white rot fungus Flammulina velutipes.
abstract: β-Glucosidase production by the white rot fungus Flammulina velutipes CFK 3111 was evaluated using different carbon and nitrogen sources under submerged fermentation. Maximal extracellular enzyme production was 1.6 U/ml, corresponding to a culture grown in sucrose 40 g/l and asparagine 10 g/l. High production yield was also obtained with glucose 10 g/l and asparagine 4 g/l medium (0.5 U/ml). Parameters affecting the enzyme activity were studied using p-nitrophenyl-β-D-glucopyranoside as the substrate. Optimal activity was found at 50°C and pHs 5.0 to 6.0. Under these conditions, β-glucosidase retained 25% of its initial activity after 12 h of incubation and exhibited a half-life of 5 h. The addition of MgCl2, urea, and ethanol enhanced the β-glucosidase activity up to 47%, whereas FeCl2, CuSO4, Cd(NO3)2, and cetyltrimethylammonium bromide inflicted a strong inhibitory effect. Glucose and cellobiose also showed an inhibitory effect on the β-glucosidase activity in a concentration-dependent manner. The enzyme had an estimated molecular mass of 75 kDa. To the best of our knowledge, F. velutipes CFK 3111 β-glucosidase production is amongst the highest reported to date, in a basidiomycetous fungus.
authors.affiliation: Laboratorio de Micología Experimental, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, PROPLAME-PRHIDEB CONICET, Buenos Aires, Argentina.
authors.forename: Julieta
authors.initials: J
authors.lastname: Mallerman
authors.forename: Leandro
authors.initials: L
authors.lastname: Papinutti
authors.forename: Laura
authors.initials: L
authors.lastname: Levin
mesh_terms: D002475:Cellobiose / Q000378:metabolism; D003470:Culture Media; D004795:Enzyme Stability; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D055393:Flammulina / Q000201:enzymology*; D005947:Glucose / Q000378:metabolism; D005960:Glucosides; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D013379:Substrate Specificity; D013696:Temperature; D001617:beta-Glucosidase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D003470:Culture Media; D005960:Glucosides; D002475:Cellobiose; C025193:4-nitrophenyl beta-D-glucoside; D000431:Ethanol; D001617:beta-Glucosidase; D005947:Glucose