Generalized transduction by phage P22 in Salmonella typhimurium. I. Molecular origin of transducing DNA.

P22, a temperate phage which grows on Salmoneua typhimurium, is capable of carrying out general&d transduction in this host. The general&d transducing particles are the same size ss P22 phage particles but instead of phage DNA they contain bacterial DNA which was synthesized before phage infection. Further, DNA molecules isolated from the transducing particles have the same molecular weight as P22 DNA, 27 x IO6 daltons. Examination of the formation of transducing particles under conditions in which the AS’. typhimurium recombination system (WC) end/or the P22 recombination system (erf) are defective indicates that neither of these general recombination systems is necessary for the formation of transducing particles.