Derivation and properties of Proteus mirabilis systems for high frequency transduction of streptomycin--sulphonamide and streptomycin-sulphonamide--kanamycin resistances.

Properties of two transducing systems with phages capable of high frequency transduction (HFT) of streptomycin and sulphonamide resistance markers of the V group plasmid R905, and of these markers plus the kanamycin resistance marker derived from a previously described HFT phage 5006MHFTak, are described. Transducing particles of the former phage, named 5006MHFTsus, were detected using the replica-plate technique in an ultraviolet-induced lysate of Proteus mirabilis strain PM5006 transduced to streptomycin and sulphonamide resistance by phage 5006M grown on PM5006 carrying R905. Phage 5006MHFTsusk was also detected by the replica-plate technique in ultraviolet-induced lysates of of phage 5006MHFTsus transductants retransduced to ampicillin and kanamycin resistance by phage 5006MHFTak. Both phages were serologically identical to the parent phage 5006M. Ultraviolet-induced lysates transduced their markers to PM5006 at frequencies of about 5 X 10(-2)/plaque-forming unit adsorbed for both the phages. With phage 5006MHFTsusk, this frequency was increased about 10-fold by simultaneous infection of recipients with homologous non-transducing phage, while phage 5006MHFTsus transductions only underwent a twofold increase. Transductants took about 60 min to express complete resistance to 50 mug streptomycin/ml, and resistance to 1600 mug sulphadiazine/ml was complete within 120 min after phage adsorption. Phage 5006MHFTsusk was slightly more resistant to ultraviolet inaction of its transducing potential and reasons are given for the belief that transductants of both phages are heterogenote-like. Both phage lysates were also capable of generalized transduction and, like previously described HFT phages, lysates transduced the leucine marker at increased frequencies. Using previously described extra- and intra-species phages hosts, it was found that the phages could transduce in single infection and were defective in the lysogenic conversion function as well as in a maturation step. Possible modes of formation of the HFT particles are discussed9