[Mechanism of plasmid ColEl and pMB-9 mobilization by plasmid F'lac+ in Escherichia coli K-12].

The genetic control and mechanism of mobilization of the non-conjugative plasmids ColE1 and pMB-9 by the conjugative plasmids was orived to be recA-independent process in contrast to the mobilization of the chromosomal marker pro. Acridine orange and ethidium bromide curing data together with the results of electrophoretic analysis of plasmid DNA suggest that the plasmids F' lac+ and pMB-9 as well as F' lac+ and ColE1 remain autonomous after their contransfer to recipient cells. These data argue in favour of non-recombinational nature of the plasmid mobilization process. The possibility of transmission of a non-conjugative plasmid without transmission of a conjugative one from the donor strain carrying both plasmids was established. The results obtained are discussed with respect to the hypothesis on the effect of diffusible products encoded by the conjugative plasmid and required of the mobilization of the non-conjugative plasmid.