[Conjugative properties of the R factors found in 2 different strains of Escherichia coli].

The transfer frequency of R124-17, RI, RI-19 and RP4 factors as dependent on the origin of the donor strain was studied. The transfer frequencies of these factors from E. coli W strains are much lower than those from the strains of E. coli K12. The effect is connected neither with the repression of the tra-genes, nor with the restriction enzymes activity against the alien DNA in the recipient bacteria.