Chemical mutagenesis and the use of indirect enzymatic criteria for the selection of virulent clones of Bacillus thuringiensis

The effect of the mutagene nitrosoguanidine (N-methyl-N'-nitro-N-nitrosoguanidine) on the growth of Bacillus thuringiensis subsp. galleriae st. 69/6 was being studied. It depends on the physiological state of the cells, dose of the mutagene, pH of the culture medium and exposition. Nitrosoguanidine was found to have the maximum mutagenic effect on the vegetative cells at pH 6.2 and on the spores at pH 5.6.