Cold Plasma Inactivation of Bacillus cereus and Bacillus anthracis (Anthrax) Spores

Bacillus spores represent one of the most resistant organisms to conventional sterilization methods. This paper is focused on the inactivation of the spores of two Bacillus species, Bacillus cereus and Bacillus anthracis, using atmospheric-pressure dielectric-barrier-discharge (DBD) plasma. Spores treated in liquid or air-dried on a solid surface were effectively inactivated within 1 min of DBD plasma treatment at a discharge power of 0.3 W/cm². Results of a series of model experiments show that neutral reactive oxygen species and UV radiation play a dominant role in the inactivation of spores. We also show that 45 s of the DBD plasma treatment of air-dried spores placed inside closed plastic or paper envelopes permits up to 7 log reduction of viable spores.