Behavior of Coliphage Lambda in Hybrids BetweenEscherichia coliandSalmonella

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Abstract
Salmonella typhosahybrids able to adsorb lambda were obtained by matingS. typhosarecipients withEscherichia coliK-12 donors. After adsorption of wild-type λ to theseS. typhosahybrids, no plaques or infective centers could be detected.E. coliK-12gal+genes carried by the defective phage λdgwere transduced toS. typhosahybrids with HFT lysates derived fromE. coliheterogenotes. The lysogenic state which resulted in theS. typhosahybrids aftergal+transduction differed from that ofE. coli. Ability to produce λ, initially present, was permanently segregated by transductants of theS. typhosahybrid.S. typhosalysogens did not lyse upon treatment for phage induction with mitomycin C, ultraviolet light, or heat in the case of thermoinducible λ. A further difference in the behavior of λ inSalmonellahybrids was the absence of zygotic induction of the prophage when transferred fromE. coliK-12 donors toS. typhosa. A new λ mutant class, capable of forming plaques onS. typhosahybrids refractory to wild-type λ, was isolated at low frequency by plating λ onS. typhosahybrid WR4254. Such mutants have been designated as λsx, and a mutant allele of λsxwas located between the P and Q genes of the λ chromosome. Plaques were formed also on theS. typhosahybrid host with a series of λi21hybrid phages which contain the N gene of phage 21. The significance of these results in terms ofSalmonellaspecies as hosts for λ is discussed.