The Combined Effect of UV Irradiation and Ethanol Extract from Torilis japonica Fruit on Inactivation of Bacillus subtilis Spores

The purpose of this study was to evaluate the synergistic sporicidal effects of the ethanol extract from Torilis japonica fruit on inactivation of Bacillus subtilis spores induced by UV irradiation at a wavelength of 254nm. UV₂₅₄ exhibited the strongest inactivation effect, with the level of spores being reduced by approximately 3.6- and 4.7-log cycles, respectively, after 3 and 10min of exposure at an irradiation distance of 15cm. And an ethanol extract of T. japonica fruit at concentration of 1.0% reduced the spore counts by about 3.0-log cycles for 1h of treatment. Furthermore, a combined treatment with UV₂₅₄ irradiation and 1.0% ethanol extract of the fruit produced 4.2-5.0-log reductions of Bacillus spores at different growth stages for an exposure time of 3min. The energy required from UV irradiation to inactivate the spores was 50% lower in the presence of 1% ethanol extract of the fruit than with UV irradiation alone.