ISOLATION AND INVESTIGATION OF INDUCED ASPOROGENIC MUTANTS

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Abstract
A simple chemically defined (minimal) medium was developed which supported good growth and sporulation of B. cereus var. lacticola. Normal growth and sporulation habits in the medium were determined employing an active growth-culture technique. Induced asporogenic mutants were isolated employing ultraviolet light as the mutagen. Mutants differed in their sporulation habits from the normal culture when grown at 37 °C under the standardized conditions in a minimal synthetic medium. Three mutant cultures appeared to be temperature-sensitive mutants as regards sporulation, that is, in the minimal medium mutant cultures were able to sporulate when grown at 28 °C but were non-sporulating at 37 °C. Sporulation blocks were partially reversed when casein hydrolyzate and some low molecular weight protein building blocks were added to the synthetic medium. The pH changes of the medium during growth and sporulation of normal and mutant cultures were compared.