Transducing phages for Bacillus subtilis.

Transducing phage PBSl and a clear-plaque type mutant PBS2 derived from PBS 1 show similar growth characteristics with a relatively small burst size (23 to 24), and are related serologically. They are morphologically indistinguishable and both have a dense head of about 100 mp in diameter and a tail about 250 m p in length. PBS 1 is more efficient in transduction and its plaque-forming activity is more sensitive to ultraviolet (u.v.) irradiation than that of PBS2. The host range of the phages is limited to strains of Bacillus subtilis. All Marburg strains tested were sensitive to thelytic actionof thephages. Prophages of PBS 1 and PBS 2 were not u.v.inducible and the irradiation of lysogenic cultures with arelatively high dose of U.V. radiation resulted in considerable decrease of the free phage titre. However, transducing activities of lysates treated with a high dose of U.V. radiation were not affected significantly. Organisms lysogenic either for PBS 1 or to PBS 2 were not stable and reverted to the sensitive state.