Abortive infection of lysogenic Bacillus subtilis 168(SPO2) by bacteriophage phi 1.

Virulent bacteriophage phi1 was not able to productively infect strains of Bacillus subtilis which were lysogenic for the temperate bacteriophage SPO2, although it adsorbed to, penetrated, and killed these bacteria. Studies of phage and host nucleic acid production in the nonpermissive host demonstrated that normal phi1 transcription was initiated early in the latent period, but this was followed by a general failure of host and phage nucleic acid synthesis about 10 to 15 min after infection. Mixed infections of phi1 and SPO2c(1), a clear-plaque mutant of SPO2, indicated that a similar inhibition of phi1 development occurred when this phage infected nonlysogenic B. subtilis cells committed to the SPO2c(1) lytic cycle. It is proposed that the SPO2- and SPO2c(1)-mediated interference did not act directly on the phi1 genome, but rather these phages altered the host physiology in such a manner that some normal step in phi1 development triggered a collapse of vital metabolic activities.