不同处理条件对介质阻挡放电低温等离子体杀菌效果及影响机理研究

Sterilization by dielectric barrier discharge low temperature plasma under different treatment conditions

摘要:

[目的]研究不同处理条件下介质阻挡放电低温等离子体对单增李斯特菌和肠炎沙门氏菌的杀菌效果，以及抑菌活性物质含量随处理时间的变化。[方法]以单增李斯特菌和肠炎沙门氏菌为对象，研究不同电压、时间及氧气浓度对介质阻挡放电低温等离子体杀菌效果的影响，通过气态活性物质测定管测定O₃和NO₂浓度随处理时间的变化，利用荧光强度表征菌液中产生的活性物质浓度，采用荧光分光光度法测定·OH、H₂O₂和¹O₂随处理时间的变化。[结果]采用70 kV、150 s或80 kV、120 s能够完全杀灭肠炎沙门氏菌，而单增李斯特菌只在80 kV、120 s条件下才能被完全杀死。采用50% O₂+50% N₂的混合气体能够在90 s内完全杀死细菌。随处理时间的增加，两种菌体细胞内活性氧物质含量呈逐渐增加趋势。[结论]电压、时间及氧气浓度均能显著增强等离子体的杀菌效果，其杀菌作用主要与H₂O₂、·OH、¹O₂等活性氧物质的含量有关，其中·OH和H₂O₂是介质阻挡放电等离子体杀菌的主要物质。

Abstract:

[Objective] To study the bactericidal effect of dielectric barrier discharge low temperature plasma on Listeria monocytogenes and Salmonella Enteritidis under different treatment conditions and the content of antibacterial active substances with treatment time. [Methods] Listeria monocytogenes and Salmonella enteritidis were used as research objects to determine the total number of colonies after treatment with different voltage, time and oxygen concentration. The concentration of O₃ and NO₂ was determined by gas-active substance determination tube with treatment time and fluorescence intensity was utilized. The concentration of free radicals generated in the bacterial liquid was characterized and the changes of·OH, H₂O₂ and ¹O₂ with the treatment time were determined by fluorescence spectrophotometry. [Results] Using 70 kV, 150 s or 80 kV, 120 s could completely kill Salmonella Enteritidis, whereas Listeria monocytogenes could be completely killed only at 80 kV, 120 s. A mixture of 50% O₂+50% N₂ could completely kill the bacteria in 90 s. With the increase of treatment time, The content of intracellular ROS in two bacteria gradually increased. [Conclusion] The voltage, time and oxygen concentration could significantly enhance the bactericidal effect of plasma. Active oxygen radicals such as H₂O₂ and·OH could promote the bactericidal effect on Listeria monocytogenes and Salmonella enteritidis. Moreover, the bactericidal effect of·OH and H₂O₂ was better than that of ¹O₂.