H 2 O 2 and ·OH Radicals in Radiation Inactivation of Bacterial Spores

SummarySuspensions of Bacillus megaterium spores, when irradiated in the presence of N2O and limiting concentrations of ethanol, produce bi-phasic response curves with the high-dose line showing increased sensitivity. Experiments correlating sensitivity to concentrations of H2O2 implicate this chemical species as one sensitizing agent. H2O2 is not sensitizing, however, in the absence of ·OH, suggesting that two actions involving both species must take place for inactivation to occur. A chemical mechanism competent to explain these facts is presented. Sensitization seen in O2-saturated solutions may not be explained by this mechanism.