Colicin resistance associated with resistance factors inEscherichia coli

Abstract

Derivatives of E. coli K12 which had received a number of different drug resistance factors by conjugation from Salmonella strains were found also to have acquired insensitivity to colicins. The insensitivity associated with some R factors was similar in character to immunity conferred by colicinogeny, while that given by others more closely resembled the higher level of resistance due to absence of the colicin receptor. It was, however, not complete. Many of the R factors also restricted the growth of various phages.