Regulation of maltose metabolism in stationary phase cultures of an asporogenous mutant of Bacillus licheniformis

An asporogenous strain of Bacillus licheniformis accumulated maltose by an energy dependent transport mechanism during an extended stationary phase. Maltose transport was sensitive to the effects of the uncoupler tetrachlorosalicylanide (TCS), and was also inhibited by glucose. Maltose stimulated synthesis of a p-nitrophenyl-a-D-glucoside-hydrolysing enzyme (pNPGase) in log phase and in stationary phase cells. In the presence of glucose this induction was inhibited. Glucose was used preferentially to maltose in stationary phase cells. The uptake of maltose from the medium, and the synthesis of pNPGase, were immediately and completely inhibited in the presence of glucose. These results are consistent with a mechanism of inducer exclusion mediating the repressive effect of glucose upon pNPGase synthesis in stationary phase cells. Catabolite repression of a-amylase synthesis by glucose was also demonstrated in late stationary phase mutant cells.