Effects of some .OH scavengers on the radiation sensitizaation of bacterial spores by p-nitroacetophenone and O2 in suspension

Spores of Bacillus megaterium were irradiated in suspension with 50 kVp X-rays under three reference conditions: in anoxia (i.e., 100 per cent N2); in anoxia with 2 mM p-nitroacetophenone (PNAP), a concentration that shows the maximum amount of sensitization by this agent; and in air. The responses were then measured when different concentrations of an hydroxyl radical scavenger were also present. Allyl alcohol, t-amyl alcohol, t-butanol, ethanol, glycerol, the formate ion, and methanol were the .OH scavengers that were used. A comparison of the effects these additives had on the three reference responses provided indirect, comparative information on the sensitizing processes of PNAP and O2. Neither t-amyl alcohol or t-butanol affected the response in air or N2 alone. Both these additives, however, could reduce the sensitization from PNAP slightly. The other additives had significant protective effects under the three conditions. In general, the additives had similar effects in air and in 100 per cent N2 but much greater protective effects in PNAP. Although the sensitizing mechanisms were not identified by these experiments, the effects of O2 and PNAP, as judged by the desensitizing actions of these additives, appeared quite different. (author)