[The role of host cells in the genetic regulation of plasmid transfer in Escherichia coli].
The role of serologically typed and nontyped E. coli cells in the expression of genetic regulation systems activity for repressed plasmids transfer (types fin OP, fin U, fin V) was studied. It is shown that the inhibiting action of such plasmids on the tra-genes functions of derepressed plasmids is more expressed in the cells of serologically nontyped E. coli (K-12 strains) than in the cells of serologically typed ones (serogroups O106, O128, O147).