Unrelatedness of Temperate Bacillus subtilis Bacteriophages SPO2 and φ105

Abstract

SPO2 and φ105 are temperate Bacillus subtilis bacteriophages which have been suggested to belong to a cluster of related bacteriophages. In the present work, we show that SPO2 does not complement any of the 11 essential genes known in φ105 and that the phages do not recombine. Deoxyribonucleic acid (DNA)-DNA hybridization shows less than 10% homology between SPO2 and φ105 DNA. DNA synthesis in φ105 shows a greater dependence on host functions than does SPO2 DNA synthesis. Growth of φ105 but not of SPO2 is inhibited by the uracil analogue 6-( p -hydroxyphenylazo)-uracil. Infection of a DNA polymerase-deficient strain of B. subtilis with SPO2 leads to an increase in DNA polymerase activity in crude extracts, whereas no such increase is found after infection of this strain with φ105. It is concluded that SPO2 and φ105 are unrelated bacteriophages.