Two mutant strains of Bacillus licheniformis insensitive to catabolite repression were selected by classical mutagenesis in connection with the development of a fed-batch procedure for protease production. B. licheniformis 4a produced up to 20 U (Anson-Units) subtilisin Carlsberg/ml in fed-batch experiments in the presence of up to 1.5 M glycerol, but was inhibited by excess ammonium. Formation of spores, excretion of alpha-amylase and the biosynthesis of citrate synthase and isocitrate dehydrogenase were likewise not repressed by glycerol. The strain was characterized by unusually low activity of the alpha-oxoglutarate dehydrogenase complex and increased biosynthesis of polyglutamic acid in the presence and excretion of alpha-oxoglutarate in the absence of ammonium, respectively. The results are discussed in view of a possible connection between the defect in the alpha-oxoglutarate dehydrogenase complex and insensitivity to catabolite repression. The second strain B. licheniformis 114 was able to synthesize 11.5 U protease/ml independently of the glycerol and ammonium concentration in the medium.