AN ASPOROGENOUS MUTANT OF BACILLUS SUBTILIS POSSIBLY LACKING IN VIVO PROTEOLYTIC ACTIVITY

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The synthesis of ribosomal RNAs in Bacillus subtilis 111 and an asporogenous mutant strain 61, derived from 111, was examined. The RNA synthesis decreased at the early stationary phase in both strains. The addition of either chloramphenicol or casein acid hydrolyzate stimulated the RNA synthesis in the parent strain. In the mutant strain, like the parent, the addition of casein acid hydrolyzate stimulated the RNA synthesis, but chloramphenicol was always without effect. The degradation of pre-formed proteins occurred in the parent strain at the stationary phase. However, no significant degradation was observed in the mutant strain. Although serine and metal proteases were found both in the culture medium and in the cell extract, these proteases were likely not to be functioning in the mutant in viva during the stationary phase. Because of the deficiency in the amino acid pool due to the lack of protease activity, the asporogenous mutant presumably failed to synthesize spore proteins.