The subject of this diploma thesis is the study of the effect of cold atmospheric plasma (CAP) on the yeast Nakaseomyces glabratus (N. glabratus), formerly known as Candida glabrata. A microwave discharge torch with direct gas flow was used as the source of CAP. The plasma jet was connected to a computer, enabling its movement across the entire surface of a Petri dish for a precisely defined time (30–480 s).
As part of this work, the recovery of treated microorganisms from the surface of plasma treated Petri dishes was first optimized. Efficient transfer of microorganisms into suspensions was achieved by shaking the agar plates in a PBS solution. Membrane permeability was subsequently examined using the fluorescent probe propidium iodide (PI), with measurements performed by flow cytometry. It was found that the highest proportion of PI positive cells occurred after 30–60 s of treatment, and that with increasing treatment time, a significant decrease in fluorescence signal was observed due to mechanical damage of the cells and the leakage of intracellular matrix, including DNA, outside the cell.
The cells were then examined for the possibility of apoptosis induction following CAP treatment, using staining with the fluorescent probes Annexin V FITC/PI. It was found that apoptosis cannot be detected using this marker in the case of N. glabratus.
The enzymatic activity of catalase and superoxide dismutase (SOD) was further examined using commercially available kits. In the case of catalase, enzymatic activity was found to increase with longer treatment times. For SOD, no consistent statistically significant differences were observed. Experiments focused on the expression of selected genes associated with oxidative stress in N. glabratus revealed increased expression of CTA1 and YAP1 following CAP treatment compared to the control.