[Nature of rec+ revertants isolated from E. coli K-12 cultures mutant with regard to gene rec A].

The nature of Rec+ revertants isolated from the E. coli K-12 AB 2463 recA13 defective strain cultures was ascertained by transduction of the recA gene region into the cells of the JC 2915F- strain with the aid of P1 vira phage. Then the recombination capacity of the transductants was tested by crossing with the JC 158 Hfr strain, and the UV sensitivity of the transductants was determined. Besides, the response of the transductants to the suppression phages was examined. As revealed, the REc+ revertants were characterized by differences in the recA gene. In a number of Rec+ revertants phenotype Rec+ appeared as a result of reverse mutation in this gene from rec- to rec+, whereas in other revertants Rec+ phenotype was due to indirect suppression.