Growth, sporulation, and enzyme defects of glucosamine mutants of Bacillus subtilis

Abstract

Two glucosamine (GCA)-requiring mutants have been isolated which grow on glucose minimal or nutrient sporulation medium only in the presence of either GCA or acetyl-GCA. They lack the l-glutamine-d-fructose-6-phosphate aminotransferase (EC 2.6.1.13), which is repressible by GCA and whose activity in the standard strain decreases after cessation of growth. But the mutants can grow on GCA as sole carbon and ammonia source, because GCA induces the synthesis of 2-amino-2-deoxy-d-glucose-6-phosphate ketol-isomerase (deaminating) (EC 5.3.1.10). With respect to sporulation, the GCA-requiring mutants are in a serious dilemma, as GCA represses the onset of massive sporulation and yet a small amount of GCA-6-phosphate derivatives is necessary to allow sporulation. When GCA is continuously provided in small quantities, sporelike particles are produced which contain little or no spore cortex but a normal spore coat. Apparently, GCA derivatives are needed especially for cortex formation. Many of the sporelike particles can produce colonies after octanol, but not after heat treatment. When they are purified by treatment with lysozyme and sodium dodecylsulfate, they do not show the decrease in optical density at 600 nm typical of germination nor do they produce offspring.