Loss of R Factors Promoted by Bacteriophage M13 and the M13 Carrier State

Abstract

The infection of different Hfr strains of Escherichia coli bearing derepressed R factors of the fi + or fi − type can result in the loss of the R factor and the conversion of the infected cells to the R − state. This extends earlier observations on the elimination of F′ factors by bacteriophage M13 infection. Variability in the efficiency of this conversion can arise because of genetic factors independent of the R factor being eliminated. A fraction of the infected but unconverted R + cells were M13 carrier strains. The carrier state had an intracellular basis, and single R + cells could maintain the carrier state.