Effect of oxygen, chemical agents, dose rate and temperature on the radiation response of wet spores

The post-irradiation sensitizing effects of oxygen are described. Wet spores of Bacillus megaterium equilibrated with 100% N2 were irradiated and held in nitrogen in the sample chamber for various times before exposure to O2 delivered at high pressure. The irradiation source was a field emission accelerator. The surviving fractions were measured after single pulses of electrons providing a dose of 430 krads to anoxic spores. The ability of O2 to sensitize the spores after irradiation decreased with increasing time reaching zero after 10-15 min in N2. Results indicate the existence of a slowly decaying radiation-induced component or lesion which when combined with O2 is lethal to the wet spore. 5 references, 4 figures