[Sensitivity of dissociation variants of Micrococcus luteus to the action of delta-endotoxins of Bacillus thuringiensis].

Endotoxins of Bacillus thuringiensis subsp. tenebrionis produced an antibiotic effect on three out of the four species of micrococci tested, showing an activity of 10-23 units/mg, comparable with that of bacitracin. The R variants of Micrococcus luteus were more than twice as resistant to the action of delta-endotoxins as cells of the S and M types. Enhanced growth of the tested microorganisms at concentrations of antibiotics large enough to inhibit the growth of the S and M variants, but insufficient to suppress the R-variant, was shown to be determined by the intense development of the latter variant.