Glucose suppression of β-glucosidase activity in a chloramphenicol-producing strain of Streptomyces venezuelae

Abstract

β-Glucosidase activity was induced in Streptomyces venezuelae during growth on cellobiose, gentiobiose, salicin, methyl β-glucoside, and p-nitrophenyl β-D-glucopyranoside. Activity in cell extracts was separated by DEAE-cellulose chromatography into two fractions differing in substrate preference. One component showed higher activity with, and was more strongly induced by, cellobiose; the other showed greater activity and inducibility with salicin. Addition of glucose to cultures severely depressed induction of β-glucosidase activity by cellobiose but not by salicin. Acetate and several amino acids inhibited induction by either substrate. The action of glucose was not reversed by cyclic AMP. Cultures of S. venezuelae using glucose, cellobiose, or a mixture of the two saccharides as their carbon source produced chloramphenicol during growth. In contrast with its effect on the induction of cellobiase activity, glucose did not suppress chloramphenicol production, indicating that the control mechanisms that establish carbon source preferences are not linked to those that regulate antibiotic biosynthesis in this organism.