Properties of a plasmid pRY82, mediating lactose-utilization, isolated from a Salmonella litchfield strain

Abstract

A lactose-positive strain of Salmonella litchfield was isolated from periproctal absess. The lactose-positive character of the strain was attributed to a plasmid with a molecular weight of about 130 megadaltons. This plasmid, pRY82, was conjugally nontransmissible but was mobilized by plasmid pTH10. Resistance to chloramphenicol, streptomycin, sulfamethoxazole, tetracycline and potassium tellurite as well as inhibition of development of bacteriophages T7 and lambda were mediated by pRY82. It was suggested that pRY82 is a member of the H2 incompatibility group. During the course of the test for incompatibility, recombination between pRY82 and R478 DNAs occurred in high frequency to form new plasmids mediating lactose-utilization and resistance to kanamycin.