Deficiencies or excesses of metabolites interfering with differentiation.

Auxotrophic mutants of Bacillus subtilis need much higher concentrations of the required adenine, nicotinic acid, riboflavin, thiamine, or tryptophan for optimal sporulation than for maximal growth. Acetate can partially replace thiamine, indicating the importance of the pyruvate dehydrogenase system for differentiation. A glycerol-requiring mutant can sporulate only if its cells contain a small concentration of L-alpha-glycerol phosphate during development. This can best be achieved by excess (>/=5 mM) of extracellular alpha-glycerol phosphate, which enters B. subtilis very slowly. The results show that both biosynthetic and catabolic enzymes are often needed to maintain the precise balance of metabolites required for differentiation. Mutants unable to catabolize fructose 6-phosphate, glucose 6-phosphate, or alpha-glycerol phosphate do not sporulate as long as these compounds accumulate inside the cells; their development is blocked before prespore septa have formed.