BACILLUS SUBTILIS DEOXYRIBONUCLEIC ACID TRANSFER IN PBS2 TRANSDUCTION.

Mahler, I. (Brandeis University, Waltham, Mass.), M. Cahoon, and J. Marmur. Bacillus subtilis deoxyribonucleic acid transfer in PBS2 transduction. J. Bacteriol. 87:1423-1428. 1964.-Lysates of the general transducing bacteriophage PBS2 grown on Bacillus subtilis SB19 were fractionated by preparative CsCl density-gradient centrifugation. Five distinct and separate bands which varied in their ability to transduce three nutritional markers were obtained by this procedure. Deoxyribonucleic acid (DNA) samples prepared from unfractionated lysates and from each of the separate bands were examined by analytical CsCl density-gradient centrifugation. In addition to a major band (density, 1.723 g/cc) identified as PBS2 DNA, a satellite band of lighter density was detectable in the nucleic acids obtained from whole lysates and those bands that possessed transducing activity. The biological activity of the purified nucleic acids, determined by transformation experiments, was found to reside in the light satellite band (1.703 g/cc) characteristic of B. subtilis DNA. In view of the correlation between general transducing ability of phage particles and the presence of bacterial DNA which appears not to be physically associated with the phage DNA, it is suggested that transduction by bacteriophage PBS2 does not depend upon areas of homology between the phage genome and the host chromosome but resides in specific particles which have incorporated segments of bacterial DNA.