Inactivating gram-positive microorganism by using atmospheric pressure discharges with water mist

Abstract

Abstract Dusty plasmas corresponding to plasmas containing micro-particles have interested plasma scientists for a few decades. In this study, a plasma including water mist is introduced as the dusty plasma, with potential for applications to biological and other engineering techniques. The plasma with water mist was generated by combining a dielectric barrier discharge with an Ar gas flow transporting the water mist in the atmosphere. The water mist in the discharge enhanced inactivating spores of a microorganism (Geobacillus stearothermophilus). Under these conditions, optical emission of OH radicals from the discharge center was clearly observed. The spores were little affected by the water mist directly introduced to them under the discharge but were effectively inactivated by discharge plasma involving the water mist. The O and N species produced by the metastable Ar in the atmosphere, and possible OH radicals excited by the discharge in the water mist, are discussed as the likely reaction schemes of spore inactivation.