FURTHER STUDIES ON AN ASPOROGENOUS MUTANT OF BACILLUS SUBTILIS LACKING IN VIVO PROTEOLYTIC ACTIVITY

Abstract

Various properties such as pH optimum, response to metal ions and inhibitors, and heat stability of two extracellular and one intracellular proteases from both parent and asporogenous strains of Bacillus subtilis were examined, and no significant difference between the two strains was observed. The intracellular protease was shown to be a serine protease absolutely requiring Ca²⁺. We examined in vivo degradation of the cellular protein at the stationary phase in both parent and mutant strains and found that degradation occurred only in the parent strain. Addition of Ca²⁺ and toluene together to the reaction mixture of the mutant strain, however, resulted in significant degradation of the cellular protein in the mutant strain, although the addition of either Ca²⁺ or toluene alone had no stimulating effect on the degradation. These results suggest that the mutant strain is defective in its transport system for Ca²⁺.