α∈-Diaminopimelic acid metabolism and sporulation in Bacillus sphaericus

Abstract

In B. sphaericus, B. sphaericus var. fusiformis and B. sphaericus var. rotans ae -diaminopimelic acid (DAP) was present in sporulating cells and spores but not in vegatative cells. As in other Bacillus spp., pyridine-2:6-dicarboxylic acid was built up as a Ca salt in the developing spore. A peptide containing DAP, aspartic acid, glutamic acid, alanine and hexosamines appeared in spore extracts and germination exudates. A peptide containing lysine, aspartic acid, glutamic acid, alanine and hexosamines was isolated from vegetative cell walls by treatment with lysozyme. Vegetative cells showed strong DAP decarboxylase activity, stimulated by pyridoxal phosphate; QN2CO2 values in nitrogen were 20-30. Lysine was a reaction product but no cadaverine was detected. Sporulating cells were less active [image]. These values were obtained with disintegrated cells. Sporulating cells and spores gave lower [image] values when tested intact. The DAP decarboxylase activity of spores was relatively heat-stable. There was no increase in decarboxylase activity during germination and development to the first vegetative cell. During spore germination, the decarboxylase system became less heat-stable. Pyridine-2:6-dicarboxylic acid and piperidine-2:6-dicarboxylic acid were not decarboxylated by vegetative cells of B. sphaericus; in equimolar concentration they did not inhibit the decarboxylation of DAP by these cells. Vegetative cells, sporulating cells and spores showed negligible DAP racemase activity. Some possible relationships between DAP metabolism and sporulation in B. sphaericus are discussed.