PROPERTIES OF F′ STRAINS OF ESCHERICHIA COLI SUPERINFECTED WITH F-LACTOSE AND F-GALATOSE EPISOMES

Abstract

Echols, Harrison (University of Wisconsin, Madison). Properties of F′ strains of Escherichia coli superinfected with F-lactose and F-galactose episomes. J. Bacteriol. 85: 262–268. 1963.—A study of F′ superinfection of F′ strains of Escherichia coli by F Lac P and F Gal indicates that superinfecting F Lac P may achieve a stable existence along with native F Lac P in approximately 1% of the recipient F′ population. The stable presence of F Gal, on the other hand, leads to a displacement or suppression of F Lac P when F Gal is used as a superinfecting agent or as the native episome. The majority of F′ bacteria used as recipients neither acquire in stable form the superinfecting F-linked genes nor demonstrate gene activity immediately after attempted transfer, as judged by alkaline phosphatase synthesis directed by an F-transferred P + gene. This failure to show gene activity suggests that the F′ bacteria which are sterile as recipients exclude transfer rather than inhibit subsequent multiplication.