Restoration of Escherichia coli Strain B after irradiation

Abstract

The fraction of bacteria of a proline-requiring auxotrophic strain of E. coli strain B which was able to originate macrocolonies on a defined nutrient medium after exposure to gamma-rays under anoxic conditions was markedly increased when the organisms were deprived of proline or were treated with chloramphenicol for the initial period after irradiation. Either treatment was equally effective and the maximum degree of survival which was obtained was above that observed when the cells had been incubated throughout on a proline + inorganic salts + glucose medium. The depression in survival caused by including NaCl in the defined nutrient medium, on which the irradiated bacteria were grown, was completely eliminated by both treatments. "Rescue" appears to depend on the temporary inhibition of protein synthesis.