Genetic studies of strain Bs8 ofEscherichia coli

Abstract

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 with gal+. When uvr8 was transduced into radiation-resistant strain B/r the resulting phenotype was indistinguishable from Bs8. When transduced into a lon K-12 strain the phenotype was more sensitive than Bs8, filament-inducible and mucoid. When PI-Bs8 was used to transduce proC+ into a proC K-12 strain, 4% of the transductants were lon, i.e. about as u.v.-sensitive as Ion K-12, filament-inducible and mucoid. Radiation resistance could not be transduced from strain Bs8 with proC+ into a proC lon 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.