Episome-mediated transfer of drug resistance in Enterobacteriaceae IV. Interactions between resistance transfer factor and F-factor in Escherichia coli K-12.

Watanabe, T. (Keio University, Tokyo, Japan) and T. Fukasawa. Episome-mediated transfer of drug resistance in Enterobacteriaceae. IV. Interactions between resistance transfer factor and F-factor in Escherichia coli K-12. J. Bacteriol. 83:727-735. 1962. - Resistance transfer factor (RTF) present in F(+) and F'(+) strains was found to suppress completely the transfer of F-factor, F', and host chromosomes. On the other hand, the presence of RTF in Hfr strains was found to reduce the frequencies of recombination to about 10(-2) of those in Hfr strains, regardless of the types of Hfr. RTF present in an F(+) strain with colicinogenic factor E(1) inhibited the transfer of the colicinogenic factor, whereas the transfer of colicinogenic factor I was not suppressed by RTF. A hypothesis that the genetic determinant of RTF controlling its "transfer system" is epistatic to that of F-factor is presented. It was also shown that F-factor present in recipients slightly suppresses the acceptance of RTF and that RTF present in recipients slightly reduces the acceptance of F-factor, F', and host chromosomes. On the other hand, the acceptance of RTF by recipients in which RTF is present was found to be about 1% of that in recipients without RTF.