SUMMARY: Only strain PV127 out of many and Providence strains was transduced to kanamycin resistance by high-frequency transducing variants, 5006MHFT and 5006MHFT of phage 5006M, a general transducing phage for strain PM5006. The phages adsorbed poorly to strain PV127 and did not form plaques. The transduction frequency of PV127 by these phages was 5 × 10/p.f.u. adsorbed. Phage 5006M increased the transduction frequencies. Abortive transductants were not detected. Transductants segregated kanamycin-sensitive clones at high frequency and this, together with data from the inactivation of transducing activity of lysates by ultraviolet irradiation, indicated that transduction was by lysogenization. The general transducing property of the phages was not expressed in transductions to auxotrophs of PV127. Transductants (type I) resulting from low multiplicities of phage input adsorbed phage to the same extent as PV127. This suggested a defect in the transducing particles (or host) because single phage 5006M infection converted strain PM5006 to non-adsorption of homologous phage. Type I transductants did not liberate phage, suggesting a defective phage maturation function. Transductants (type II) which arose from higher multiplicities of phage input did not adsorb phage, indicating possible heterogeneity among transducing particles. Phage derived from type II transductants adsorbed poorly to PV127 and transduced it to kanamycin resistance at frequencies similar to those of phages 5006MHFT and 5006MHFT ruling out host-controlled modification as a cause of the low transduction frequencies. This phage transduced PM5006 to antibiotic resistance at high frequencies but generalized transduction was again not detected. It was suggested that general transduction could be performed by particles which, due to a different composition and/or mode of chromosomal integration, made material they carried susceptible to host-cell modification.


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