Dielectric barrier discharge air plasma as a comprehensive disinfection approach to E. coli and S. aureus biofilm management

This study aimed to assess the potential of Dielectric Barrier Discharge (DBD) cold atmospheric air plasma for E. coli and S. aureus biofilm management. The bacterial biofilms were grown on stainless-steel coupons and treated with plasma for 1 and 5 min. The results indicate the reduction of E. coli and S. aureus up to 4.3 log CFU ml-1 and 3.3 log CFU ml-1, respectively. The optical emission spectroscopy (OES) shows a possible presence of OH and O species as well as the abundance of N2 and N2+ features in the plasma. Furthermore, Fourier Transform Infrared Spectroscopy (FTIR) revealed changes in wavelengths that are specific for carbohydrates, lipids and proteins when biofilms are treated with plasma for 5 min. This effect was also confirmed by x-ray photoelectron spectroscopy (XPS) as carbon species were decreased after plasma treatment whereas phosphorus and potassium were increased due to release from destructed cell wall. Furthermore, confocal laser scanning microscopy (CLSM) shows the effect of removing biofilm from the surface, where this effect was the most predominant for 5 min plasma treatment. All in all, our study demonstrates that DBD atmospheric air plasma can effectively reduce biofilm viability due to the presence of reactive nitrogen and possible oxygen species within a phase. Moreover, the applied treatment resulted in the successful eradication of biofilms on the surface of stainless-steel coupons.