Impact of plasma-activated water on the cultivability of Vibrio cholerae and Shigella sp. in aquatic microcosm

Abstract

This study investigated the impact of plasma-activated water (PAW) on the cultivability of Vibrio cholerae and Shigella sp. in an aquatic microcosm. A series of experiments was conducted with various activation times of water (5, 10, 15 and 20 min), PAW volumes (2, 5, 10 and 15 mL), incubation temperatures (7, 37 and 44°C), and exposure times (15, 30, 45 and 60 min). The results demonstrated that PAW at 20 minutes in combination with a volume of 15 mL resulted in up to 100% bacterial inhibition. Vibrio cholerae is highly sensitive to PAW, achieving log reduction values (LRVs) of up to 4.20. This value is generally obtained at 37°C or 44°C with 20 mL of PAW, corresponding to the inhibition of more than 99.99% of the bacteria. Shigella sp. showed lower LRVs, with a maximum of 2.66 under the same conditions, indicating moderate resistance to PAW. Temperature had a strong synergistic effect on V. cholerae inhibition, but a limited influence on Shigella sp. However, the observed antimicrobial effect of PAW is attributed to the presence of plasma generated long life reactive oxygen and nitrogen species (H 2 O 2 , HNO 2 , HNO 3 and HOONO 2 ), which induce oxidative stress, membrane rupture, and cell death.