Inactivation of Bacillus subtilis Spores in Water by a Direct-Current, Cold Atmospheric-Pressure Air Plasma Microjet

Bacillus subtilis spores suspended in distilled water was effectively inactivated in 6?min by a direct-current atmospheric pressure non-thermal air plasma microjet. Scanning electron microscopic images show clear distortion and debris of spores after plasma treatment. Direct contribution by temperature and pH change of water as well as relatively long lived species in plasma activated water (PAW) is excluded. Short lived species (such as center dot OH, center dot O?2- and O2(1 Delta g)) are detected in the plasma-water system by electron spin resonance spectroscopy, and are considered to be the most important agents in the inactivation process.