Isolation and Properties of Bacillus subtilis Strains Lysogenized by a Clear Plaque Mutant of Bacteriophage φ105

Abstract A clear plaque mutant of the temperate Bacillus phage 105 lysogenized a small fraction of infected cells forming an integrated prophage at or near the normal 105 insertion site. These lysogens exhibited a spontaneous induction rate approximately 1,000-fold lower than wild type and were noninducible (ind-) by mitomycin C. Prophage was induced, however, when competent cultures were incubated with transforming DNA. The ind- phenotype could not be attributed solely to the clear plaque mutation and appears to involve a cell-specific factor. Lysogenization by the clear plaque mutant, in contrast to wild-type phage, did not cause a marked reduction in transformation efficiency.