Appearance of transducing particles and the fate of host DNA after infection of Salmonella typhimurium with P22-mutants with increased transducing ability (HT-mutants).

The kinetics of production of transducing particles for different bacterial markers were followed by premature lysis of Salmonella typhimurium cells infected with P22 phages. The were compared for cells infected with wild type phage or with HT-mutants which show increased transduction frequencies. Measuring the sedimentation velocity of bacterial DNA of cells infected with wild type or HT-phages, it was shown that: a) there is no cutting of DNA at random; b) original fragments necessary for packaging host DNA into transducing particles cannot be smaller than 10 phage-genome lengths; c) cutting of transducing fragments leads immediately to the right length; d) there is no loss of precipitable DNA due to phage infection.