Restriction and modification in Bacillus subtilis. Induction of a modifying activity in Bacillus subtilis 168.

Bacillus subtilis strain 5GR will restrict and modify phage SPO2 previously grown in strain 168. SPO2 grown in 168 pretreated with Mitomycin C is less restricted by 5GR. Strain MB500 is temperature inducible for the defective PBSX prophage (Siegel and Marmur, 1969). SPO2 grown in MB500 at inducing temperature is less restricted by 5GR compared to phage grown in MB500 at non-inducing temperature. It is suggested that strain 168 carries genetic determinants for modification of SPO2 DNA, and that those determinants may be associated with the defective phage PBSX.