SUMMARY: The properties of three transducing phages derived from providence strains NCTC 9207, 9246, 9290 and phage M derived from NCTC 10041 are described. The providence phages are present in supernatant fluids of young broth cultures; phage M is ultraviolet-inducible. The 3 providence phages only attack and transduce into providence strains NCTC 9211, 9295; the action of phage M is restricted to NCTC 2815. The phages transduce different markers at rates of 3 x 10—1 x 10/phage adsorbed and are thus capable of generalized transduction. No abortive transductants were encountered. The providence phages are serologically related. Morphologically the phages resemble the salmonella transducing phage P22 but phage M differs in that it possesses a delicate collar round the short neck. The infectivity of the phages is Ca independant. Phage M is more heat susceptible than the providence phages while its transducing particles are chloroform sensitive. Mutants of providence NCTC 9211, 9295 lysogenized by the phages are competent recipients in transduction experiments, while mutants of strain NCTC 2815 lysogenized by phage M yield no transductants when treated with suitable lysates of this phage. Small doses of ultraviolet irradiation of providence phages increase transduction rates. Phage M lysates similarly treated show no such stimulation. The phages have deoxyribonucleic acid base compositions similar to the organisms which they transduce and density gradient centrifugation reveals that transducing activity forms single peaks 2 or 3 fractions heavier than corresponding plaque-forming particles.


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