Some Properties of the PBP1 Transduction System in Bacillus pumilus

Bacteriophage PBP1 is a flagella-specific virus that performs generalized transduction in strains of Bacillus pumilus. PBP1 is morphologically and serologically distinct from two other flagella-specific phages, PBS1 and SP-15, which perform generalized transduction in certain Bacillus species. The DNA extracted from PBP1 particles has a buoyant density of 1.690 g/cm 3 in cesium chloride gradients, a melting temperature of 86.1 C, and a sedimentation velocity of 47 S in neutral sucrose gradients. Assuming the molecule is a linear duplex, PBP1 DNA has a molecular weight of approximately 76 × 10 6 . In two strains of B. pumilus which are sensitive to both PBP1 and PBS1, co-transducible genetic markers are more tightly linked by PBS1 transduction than by PBP1 transduction. The size of the fragment of bacterial DNA carried by PBP1-transducing particles, inferred from transduction studies and sedimentation analysis of viral DNA, suggests that PBP1 may be useful for genetic studies of extrachromosomal DNA elements present in two strains of B. pumilus. Genetic exchange of chromosomally located genes between the plasmid + and plasmid - B. pumilus strains NRS 576 and NRRL B-3275 has been demonstrated by PBP1 transduction.