Changes in DNase activities in Bacillus subtilis infected with bacteriophage PBS 1.

DNase activities in Bacillus subtilis were fractionated by chromatography on hydroxylapatite. One of the fractions hydrolyzed uracil-containing phage DNA but had no activity on host DNA. This activity on native phage DNA disappeared soon after phage infection, whereas DNase activities on bacterial DNA remained at the same level during phage development. An inhibitor of protein nature was induced by phage infection and this inhibitor was shown to be responsible for the disappearance of the DNase activity on phage DNA. Bacterial DNA in infected cells might be fragmented but is not degraded to acid-soluble oligonucleotides.