CONJUGAL FERTILITY ASSOCIATED WITH RESISTANCE FACTOR R IN ESCHERICHIA COLI

Abstract

The introduction of the contagious drug-resistance factor, R, into an F- strain of Escherichia coli allows the R+F- strain to mate with F-R-strains. The chromosome fragment transferred from the R+ cell is relatively large, comparable to the conjugation between F+ or Hfr male and F- female bacteria. The complex R factor has been analyzed by transduction with phage Pl. Within the R factor, the fertility determinant is inseparable from the determinant responsible for its infectivity, but can be separated from the loci for drug resistance. R thus resembles the category of complex F factors (F-primes) previously analyzed.