等离子体活化水对沙门氏菌的灭活作用及机制研究

等离子体活化水（Plasma-activated water，PAW）是一种新兴的非热杀菌技术，在食品保鲜等领域具有广泛的应用前景。本文研究了PAW处理对沙门氏菌（S. typhimurium）的杀灭效果及其作用机制。将经等离子体放电30、60和90 s得到的PAW分别记为PAW30、PAW60和PAW90。结果表明，PAW对S. typhimurium的杀菌效果随放电时间的延长而逐渐增强。当初始浓度为7.91 lg CFU/mL时，PAW60处理10 min后S. typhimurium活菌数减少了4.22 lg CFU/mL。扫描电镜（Scanning electron microscope，SEM）结果表明，PAW60处理后S. typhimurium细胞形态发生明显变化。经PAW60处理后，S. typhimurium胞外核酸和蛋白含量均显著（P<0.05）升高，表明其细胞膜通透性显著（P<0.05）增强。此外，PAW60处理破坏了S. typhimurium细胞外膜完整性，造成胞内活性氧水平显著（P<0.05）升高。以上实验结果表明，PAW处理能够有效灭活S. typhimurium，其作用机理可能与其破坏细胞结构、增强细胞膜通透性等有关。研究结果为PAW在食品杀菌保鲜中的应用提供了科学理论依据。

Inactivation Effects and Mechanisms of Plasma-Activated Wateragainst S. typhimurium

Plasma-activated water(PAW)is an emerging non-thermal sterilization technology,which shows potential applications in food preservation.The present study aimed to elucidate the antibacterial effect and underlying mechanisms of PAW against S.typhimurium cells.PAW obtained by plasma discharge for 30,60,and 90 s were recorded as PAW30,PAW60,and PAW90,respectively.The results showed that the bactericidal effect of PAW against S.typhimurium cells was gradually enhanced with the increasing plasma discharge time.The population of S.typhimurium was decreased by 4.22 lg CFU/mL after PAW60 treatment for 10 min,which was significantly(P<0.05)lower than that of the control group(7.91 lg CFU/mL).The results of scanning electron microscope(SEM)indicated that the PAW60 treatment resulted in obvious changes in the morphology of S.typhimurium cells.The PAW60 treatment also caused severe disruption of the membrane integrity and permeability of S.typhimurium cells,leading to the significant leakages of cytoplasmic nucleic acids and proteins.After the PAW60 treatment,the extracellular membrane integrity of S.typhimurium cells was destroyed and the intracellular reactive oxygen species levels were also significantly increased.In summary,PAW could effectively inactivate S.typhimurium cells,which might be related to the changes in the structure and membrane permeability of S.typhimurium cells.The results of this study provide theoretical basis for the application of PAW in food sterilization and preservation.