Inactivation of Candida albicans by Corona Discharge: The Increase of Inhibition Zones Area After Far Subsequent Exposition

Abstract

The cold atmospheric pressure plasma generated by the negative corona discharge has inhibition effect on the microorganism growth. This effect is well-known and it can be demonstrated on the surface of cultivation agar plates by the formation of inhibition zones. We exposed the cultures of Candida albicans to the negative corona discharge plasma in a special arrangement in this study: The equal doses of plasma were applied subsequently twice or four times on the same culture on one Petri dish, while the distance between exposed points was variable. Only small differences were observed in decontaminated zone areas for twice exposed agar at the shortest distance between exposed points (1.5 cm). In case of the four times exposed agars, we observed significant differences in inhibition zone areas, dependent not only on the exposition site distances, but also on the exposition order. The largest inhibition zone size was observed for the first exposition decreasing to the fourth one. To check relevancy of these dependencies, we presume to conduct further set of experiments with lower yeast concentration. In conclusion, significant difference in partial inhibition zone sizes appeared only when four expositions on one Petri dish were carried out, whereas no significant difference was observed for two subsequent expositions. The explanation of this effect may be the subject of subsequent remote exposition(s), when minute amounts of scattered active particles act on the previously exposed areas; the influence of diffused ozone may also take place.