Investigation of the Antimicrobial Impact of Cold Atmospheric Plasma on Wet and Dry Microorganisms

Abstract

This study aimed to investigate the antimicrobial effect of cold atmospheric plasma on microbially contaminated liquid films and dried surfaces. Additionally, the contribution of plasma-generated UV radiation to total inactivation was assessed. Experiments were performed using the nearfield module of the relyon piezobrush PZ3 plasma pen on Staphylococcus carnosus, Pseudomonas fluorescens, Streptococcus vestibularis and Candida auris. It was observed that in liquid, there seemed to be no obvious general sensitivity differences between Gram-positive and Gram-negative bacteria. However, all bacteria in liquids were clearly more susceptible to plasma than the yeast. In contrast, there was no significant difference between C. auris and S. carnosus on dried surfaces. The plasma emissions exhibited strong UVA and UVB radiation and only weak emissions in the UVC range. The antimicrobial impacts of the UVA and UVB emissions were negligible. However, an estimation based on two simplifications revealed that the UVC radiation probably contributed considerably to the inactivation properties of the plasma. This might be a special feature of near-field plasma application on thin liquid samples.

Keywords

• cold atmospheric plasma
• disinfection
• Staphylococcus carnosus
• Pseudomonas fluorescens
• Streptococcus vestibularis
• Candida auris