Infection of Actinomycin-Permeable Mutants of Escherichia coli with Urea-Disrupted Bacteriophage

Abstract

Intact cells of actinomycin-permeable mutants of Escherichia coli could be infected with urea-disrupted phage T4 (designated as T4π). The parental strains and the revertants, which are impermeable to actinomycin, were not susceptible to T4π unless they had been treated with agents which altered their permeability. The permeable mutants developed competence for π infection during the growth cycle; cells in the early stationary phase produced 10- to 100-fold more plaques on plating with T4π than did exponentially growing cells. Colistin (polymyxin E) was effective in converting noncompetent cells of either permeable or nonpermeable strains to the competent state. Treatment with lysozyme resulted in a considerable increase in susceptibility to T4π of permeable mutants but not of nonpermeable cells. It appears that development of competence for π infection is mainly due to alterations in the permeability barriers of the cell.