Characterization of bacteriophage SPP1 transducing particles

Bacillus subtilis lysates produced by virulent bacteriophage SPP1 retained their transducing ability upon purification from contaminating PBSX particles. The buoyant density in CsC1 of the transducing activity was indistinguishable from that of the SPP1 plaque-forming units and the sedimentation behaviour in sucrose gradients of purified transducing particles was the same as that of SPP1 phage particles. Further, high concentrations of anti-SPP1 serum inactivated transducing particles and SPPl plaque-forming units at the same rate. The transduction process was resistant to DNAase treatment, but was enhanced by temperatures that did not allow transformation. It was concluded that particles of the size, shape, density and serum-sensitivity characteristic of SPP1, but carrying bacterial DNA, are vectors in a true transduction process. Cell survival upon SPP1 infection is discussed.