Aryl beta-galactosidase from Sclerotium rolfsii: physiological and biochemical studies

Production of beta-galactosidase by Sclerotium rolfsii NCIM 1084 was studied under submerged fermentation conditions. The enzyme was produced extracellularly and constitutively on glucose. The enzyme production was enhanced when galactose, raffinose, cellobiose, sucrose, xylose, maltose, cellulose and pectin were used as carbon sources. Cellulose and diammonium hydrogen phosphate were best carbon and nitrogen sources, respectively. Surfactants such as Sag, Paraffin oil, Tween 20 and Tween 80 increased the enzyme production. Maximum yield of beta-galactosidase obtained was 3.8-4.2 nkat/ml. The optimum pH, optimum temperature and molecular weight of the beta-glactosidase were 2.7, 60 degrees C and 2,21,000 daltons, respectively. The enzyme is an aryl beta-glactosidase and did not hydrolyse lactose. The Km value for o-nitrophenyl beta-D-galactoside was 3.7 mM. Galactose and 2-mercaptoethanol inhibited the enzyme.