[Absence of various manifestations of adaptive response in Bacillus subtilis transformants].

Competent cells of Bacillus subtilis are more sensitive to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) than total population, exhibit higher level of spontaneous mutations to kanamycin resistance. However, the absolute number of mutated transformants doesn't rise with MNNG treatment in the range of 5 to 50 micrograms per ml. The adaptation to low concentrations of MNNG affects neither spontaneous nor MNNG-induced mutagenesis in the competent (transformed) cells, in contrast to their resistance which is stronger for the adapted transformants. The transformation by MNNG-treated plasmid pUB 110 doesn't reveal any difference between adapted and non-adapted cultures in transformation efficiency decline.