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Abstract
A mutant (Cbl-1) was isolated from Bacillus subtilis 168 wild type (wt) sporulating cultures grown on nutrient agar. This mutant differs from the parental strain as follows. (1) In nutrient broth the mutant excretes a substance which kills the wt cells. Therefore when grown in a mixed culture (Cbl-1 plus wt), this property leads to a take-over pattern by the Cbl-1 mutant, and the spores obtained from such a culture are entirely of the mutant type. (2) The DNA of the Cbl-1 strain has a buoyant density in CsCl of 1·714g./cm.3 while that of the normal B. subtilis 168 is 1·703 g./cm.3 although both strains have a G + C content of 42 moles %. An explanation for the higher buoyant density of the Cbl-1 DNA has not yet been found. In addition to the base ratio data, transformation and transduction experiments indicate that Cbl-1 is a mutant of B. subtilis 168.
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