It has been shown that the phenotypic dissociation of Bacillus subtilis SK1 and S. typhimurium TA100 is induced by hexylresorcinol, an exogenous non-species-specific autoregulator of pleiotropic action, which is genotoxic for both pro- and eukaryotes. Nongenotoxic homoserine lactone, a chemical analogue of cell-density-responsive species-specific regulators, does not induce bacterial dissociation. The phage resistance of the S- and R-type variants of S. typhimurium TA100 induced by hexylresorcinol has been found to be the same as that of the S- and R-type salmonella variants obtained by the routine subculturing method.