مشخصات پژوهش

Low temperature plasma is relatively newly discovered substance with great potential use not just in industry but in biomedicine too [1]. Reactive oxygen and nitrogen species are primary responsible for plasma features such as antimicrobial and antifungal properties [2] or better blood coagulation [3]. Our study was focused on plasma antifungal properties where we wanted to find proper treatment time for yeasts elimination and identified reactive species responsible for lower survival. As model organisms Schizosaccharomyces pombe and Candida parapsilosis were chosen. Yeasts were treated 5, 7 and 10 minutes with low temperature plasma generated by plasma jet with voltage 13 kV and frequency 5.2 kHz. As working gas ambient air was used. Yeasts were directly treated by plasma in distilled water and plated on Petri dishes 0, 1 and 2 hours after treatment. After the plasma treatment decreased yeast survival with increasing exposure time as well as with increasing time of cultivation in the treated water was observed. In the analysis of reactive species presence our attention was focused on the particles with longer decay, particularly on hydrogen peroxide, nitrates and nitrites. Concentration of hydrogen peroxide increased with exposure time, but it was relatively stable also 72 hours after the treatment. In contrast, concentration of nitrites rapidly decreased with exposure time. In case of nitrates no concentration dependence on exposure time or cultivation time was observed. In addition, specific reactive species applied to tested yeasts did not decrease yeast survival significantly. However, their combination had more similar effects to plasma. Our attention was also focused on morphological changes of plasma treated yeasts. C. parapsilosis (budding yeast) did not show changes in cell morphology after the treatment compared to control sample, but none of the observed yeasts divided. Contrary to C. parapsilosis, S. pombe (fission yeast) showed significant changes in c