Characterization of Escherichia coli Mutants Tolerant to Bacteriocin JF246: Two New Classes of Tolerant Mutants

Several hundred independent bacteriocin-tolerant mutants have been isolated without mutagenesis from three strains ofEscherichia coli . On the basis of patterns of sensitivity to eight different colicins, over 85% of these mutants could be grouped into four classes. Two classes of mutants, class A and class B, are equivalent totolA andtolB type mutants. We foundtolA andtolB mutants were sensitive to the antibiotic bacitracin. The other two classes of bacteriocin-tolerant mutants, class F and class G, are distinguished from other types of colicin-tolerant mutants on the basis of sensitivity to colicins, dyes, detergents, antibiotics, and chelating agents. The mutation in class F and class G mutants is located between 21 to 23 min on theE. coli chromosome. We propose to designate the loci of these mutations astolF andtolG , respectively.