[Determination of the localization of the kcpA gene on the chromosome of E. coli O124. I. Use of the type F' plasmids of varying length].

The loss of virulence was observed in some of the transconjugates of E. coli O124 in the process of the transfer of the plasmids differing in length: F' 200 PS, F'x 573 and F'x 363, carrying the genes of the chromosome area lac--pur E. The genetic determinants contributing to the ability of E. coli O124 to produce keratoconjunctivitis seem to be localized near the lactose marker, and not near E as in Sh. flexneri. In E. coli O124 these genetic determinants are probably localized on both sides of the lactose operon.