Inactivation of Biofilms Using a Low Power Atmospheric Pressure Argon Plasma Jet; the Role of Entrained Nitrogen

The inactivation of microbial biofilms using a low temperature atmospheric pressure argon plasma jet is investigated. The treatment of Staphylococcus aureus biofilms was the most effective; 78% population reduction was reached within 3 min. Higher reduction rates were found for smaller plasma-sample distances and for longer exposure time. Employing a pretreatment of the samples with ascorbic acid suggests that oxygen radicals might play a role in the inactivation process. A novel method for the quantitative analysis of spectra is introduced. It points towards an important role of entrained nitrogen and shows that excited nitrogen species are created in large abundances. These species can be important carriers of excitation energy to the biofilms or may function as important intermediate reactive species.