Genetic studies of strain Bs8 ofEscherichia coli

Strain Bs8 is a u.v.-sensitive derivative of strain B. It is unable to reactivate irradiated phage (HCR) and it cannot be induced to form filaments. The HCR properties are attributable to a gene,uvr8, cotransducible withgal+. Whenuvr8was transduced into radiation-resistant strain B/r the resulting phenotype was indistinguishable from Bs8. When transduced into alonK-12 strain the phenotype was more sensitive than Bs8, filament-inducible and mucoid. When PI-Bs8 was used to transduceproC+into aproCK-12 strain, 4% of the transductants werelon, i.e. about as u.v.-sensitive as Ion K-12, filament-inducible and mucoid. Radiation resistance could not be transduced from strain Bs8 withproC+into aproClon K-12 derivative. Nor did Bs8 show any evidence of being exr. Bs8 is a double mutant of strain B, behaving as though it were HCE, in a B/r background.