Effect of Plasma-Activated Water (PAW) Generated Using Non-Thermal Atmospheric Plasma on Phytopathogenic Bacteria

Plasma-activated water (PAW) exhibits potent antimicrobial properties attributed to the generation of diverse reactive oxygen and nitrogen species. This study assessed the effectiveness of PAW in vitro against phytopathogenic <i>Xanthomonas arboricola</i> and <i>Pseudomonas syringae</i> pv. <i>syringae</i>, which cause diseases on ornamental plants. Extending the plasma activation time of water and the incubation time of bacterial suspension in PAW increased the effectiveness of PAW. Treatments consisting of PAW activation using a power output of 200 W and a frequency of 50 Hz at different activation times and target population incubation times revealed significantly different effectiveness against <i>P. syringae</i> pv. <i>syringae</i> and <i>X. arboricola</i>. <i>X. arboricola</i> (reduction of 4.946 ± 0.20 log₁₀ CFU/ml) was more sensitive to PAW inactivation than <i>P. syringae</i> pv. <i>syringae</i> (reduction of 3 ± 0.15 log₁₀ CFU/ml). The plasma activation of water for 20 min followed by incubation of bacterial population for 180 min was proven to be the most effective treatment combination. The plasma activation time dose required to reduce the population by 90% was 7.47 ± 1.09 min for <i>P. syringae</i> pv. <i>syringae</i> and 4.45 ± 1.81 min for <i>X. arboricola</i> incubated for 180 min in PAW. The results of this study have the potential to further contribute to assessment of the effects of PAW on pathogen-infected plant tissues. In addition, the findings of this study could aid in further characterization of the reactive species formed during the plasma activation of water.