Abstract
A small fraction of the spore population of Bacillus macerans strain N.C.A. 7x1 will not develop or multiply in the presence of subtilin or penicillin. Such spores are not killed by the antibiotic, and multiply rapidly at any time following the inactivation of the antibiotic by the appropriate enzyme (trypsin or penicillinase), indicating a probable sporostatic action of these antibiotics. B. megaterium strain NRRL B-938, B. cereus. and B. subtilis strain ATCC 6633 spore populations germinate readily in the presence of subtilin and are entirely killed by this antibiotic. This behavior is also exhibited by the great majority of spores of B. macerans. The number of spores susceptible to the sporostatic action of subtilin is constant over the range of 6.5 to 40 ppm.