Induction and preliminary characterization of intracellular β-glucosidases from a cellulolytic Streptomyces strain

The cellulolytic actinomycete Streptomyces sp. QM-B814 posasses an intracellular β-glucosidase system which is induced by cellobiose and carboxymethylcellulose. Maximal β-glucosidase activity was attained 8-10 h after inducer addition to exponential phase growing cultures. The induction is depressed in the presence of glucose. The system is composed of two electrophoretically different β-glucosidase forms showing relative molecular masses of about 60 and 35 kDa, and pI values in the range 4.2-4.5. Both β-glucosidases are synthesized de novo. The enzymes share substrate preference and are both inhibited by δ-gluconolactone and p-chloromercuribenzoate. The induction pattern and glucose inhibition are similar for both enzymes. © 1995.