Novel sterilization method of Bacillus atrophaeus and Geobacillus stearothermophilus spores by low concentration chlorine dioxide gas.

Chlorine dioxide (ClO2) is a powerful disinfectant widely regarded as a safe and effective hygienic agent in pharmaceutical plants and other manufacturing facilities that require sterility. However, the efficacy of low concentrations of ClO2 gas on sterilizing spore-forming bacteria remains uncertain. In this study, we investigated the optimal conditions for disinfection of spore-forming bacteria with low concentrations of ClO2 gas using biological indicators. The results showed that 0.05 ppmv (0.13 mg/m3) ClO2 gas at 37±1℃, 86±2%RH sterilized Bacillus atrophaeus in 14 d and Geobacillus stearothermophilus in 28 d (>6 log10 reductions）. Based on these results, we propose that low concentrations of ClO2 gas are useful for controlling contamination by spore-forming bacteria in aseptic facilities.