[Induction of colicin E1 synthesis in Escherichia coli cells with different concentrations of plasmid DNA].

RRelationship between the level of induction of colicin E1 synthesis and the content of plasmid DNA in Escherichia coli K12S (E1) cells was studied. The number of Col E1 DNA copies per cell was found to decrease with growing generation time for different growth media and to increase continuously for the time of synchronous cell division cycle. No apparent relation of the level of spontaneous induction and of induction caused by N-methyl-N'-nitro-N-nitrosoguanidine to the number of Col E1 DNA copies per cell was observed. It is inferred that the content of plasmid DNA in the cells is not among the main factors determining the level of induction of colicin synthesis.