Transduction by Bacteriophage P22 in Nonsmooth Mutants of Salmonella typhimurium

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The general transducing phage P22 attacks only smooth (S) Salmonella with O antigen 12, determined by the oligosaccharide repeating unit constituting the distal part of the somatic lipopolysaccharide (LPS) side chain; non-S mutants, whose LPS contain few or no O repeating units, appear to be resistant. Auxotrophic non-S mutants of Salmonella typhimurium LT2 were tested as transductional recipients. Some transductants (0.5 to 5% as many as from S recipients) were obtained from most semirough recipients, either of class D (presumed leaky rouA mutants) or of a class due to mutation near his (presumed leaky rouB mutants), and from recipients lacking uridine diphosphogalactose epimerase or phosphomannose isomerase. Transductants were not obtained from several rouA, rouB, “heptose-negative,” and glucose-1-transferase mutants, nor from most semirough class C mutants, whose LPS side chains each bear a single O oligosaccharide unit. Most transductants evoked from non-S recipients by temperate (c+) phage P22 were nonlysogenic, and virulent P22.c2 phage was about as effective as P22.c+ in transduction to non-S recipients; probably all P22 transducing particles neither lysogenize nor kill. The extended-host-range mutant P22h gave qualitatively similar results,but evoked 5- to 30-fold more transductants from some non-S recipients than did P22. Probably, the LPS of non-S mutants susceptible to transduction contains a few O-specific oligosaccharide units, conferring a slight ability to adsorb P22 and a greater ability to adsorb P22h.

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