Cold Atmospheric Plasma and Ozone: Effects on Bacterial Inhibition, DNA Damage, and Gene Expression

ABSTRACT This study examined cold atmospheric plasma (CAP) and ozone effects on Gram‐positive ( Staphylococcus aureus ATCC 43300, Staphylococcus epidermidis ATCC 35984, Streptococcus mutans ATCC 25175) and Gram‐negative ( Pseudomonas aeruginosa ATCC 15692) bacteria. CAP was applied at 100−200 W for 0.5−5 min, and ozone at 4–6 L/min for 1–20 min. Treatments were performed directly on bacteria, on distilled water, and on water–bacteria mixtures. Viable cell counts showed direct CAP most effectively inhibited growth. Higher power and longer exposure increased inhibition. Both treatments damaged cell membranes, with effects intensifying over time. CAP upregulated recA expression (~twofold in S. aureus, P. aeruginosa ; ~15‐fold in S. mutans ). CAP and ozone effectively inhibit microbial growth by damaging cell membranes.