Effect of irradiated medium on strains of Escherichia coli deficient in known repair systems of ultraviolet damage

Abstract

Investigations on the lethal effects of gamma-ray irradiated medium on strains of Escherichia coli deficient in known systems of dark repair of UV damage revealed the possibility that this damage is not tackled by excision repair. Increased sensitivity of the rec A strain over rec+, in contrast to the increasesd sensitivity of uve+ over uvr A, indicated the involvement of the recombinational process in the repair of this damage. Some components of the irradiated minimal medium responible for lethality. An inverse relationship between lethality and inoculum size was indicated suggesting lethality to be a function of the molecules of toxic substance generaated per cell in the medium. A parallel observation was that the sensitivity of repair deficient strain increased with increase in gamma ray dose given to the medium.