TRANSDUCTION OF NITRATE REDUCTASE LOCI OF ESCHERICHIA COLI BY PHAGES PL AND LAMBDA

A lactate-nitrate medium suitable for genetic studies with nitrate reductase mutants (nar-) of Escherichia coli was devised. This permitted the selection of nar- strains by their failure to use nitrate as terminal electron acceptor during anaerobic growth, in addition to the selection procedure based on the chlorate resistance of nar- mutants. Transduction studies with phage P1 and nar- mutants from both sources demonstrated the existence of at least three nar genes in the gal region of the E. coli linkage map, their relative positions being: gal .... narF .... bio .... narD .... narE. Using λ phage cotransduction of narD with bio was observed and several independently-isolated defective λ-transducing phages were examined. Phage λ also transduced the narF gene with gal linkage but the narE gene was not λ-transducible. © 1968 Springer-Verlag.