CATABOLITE REPRESSION OF BETA-GLUCANASE SYNTHESIS IN BACILLUS-SUBTILIS

Beta-Glucanase synthesis in Bacillus subtilis was repressed by glucose and other substrates of glycolysis. Experiments with different pts mu tants showed that the phosphoenolpyruvate: sugar phosphotransferase sy stem is not involved in carbon catabolite repression of beta-glucanase synthesis. Carbon catabolite repression of beta-glucanase synthesis w as completely abolished in a ccpA mutant. An operator structure simila r to those upstream of amyE and the xyl operon was found and was shown by site-directed mutagenesis to be the target for carbon catabolite r epression of beta-glucanase synthesis. The presence of this operator o n a multi-copy plasmid resulted in a reduced repression of both beta-g lucanase and alpha-amylase synthesis. It seems likely that the gene en coding these enzymes are part of one regulon with respect to catabolit e repression.