[Possible means for increasing exotoxin synthesis by a Bacillus thuringiensis culture--the producer of bitoxibacillin].

Various procedures were studied for obtaining Bacillus thuringiensis strains of serotype I which synthesized exotoxins. Mutant clones with elevated exotoxin synthesis could be selected by treating the cells with N-methyl-N-nitro-N-nitrosoguanidine. The frequency of (+) variant selection was from 17 to 12 X 10(-2). The clones of S and R types differed in the insecticide activity of the exotoxin. Its yield could be increased by optimizing the composition of growth media. The strain specificity of B. thuringiensis producing the exotoxin was assayed in terms of carbon and nitrogen requirements.