Effects of Plasma-Activated Water on the Biofilm Structure and Genes of Listeria monocytogenes
學生姓名:
陳建霖
指導教授:
陳泰源
學期:
113上
摘 要:
As the food industry continues to evolve, food safety has become a global concern, particularly regarding foodborne pathogens. Among these pathogens, Listeria monocytogenes is a biofilm-forming bacterium that exhibits significant resistance to antimicrobials and disinfectants. Plasma-activated water (PAW), which contains various reactive oxygen and nitrogen species, has demonstrated potent antibacterial activity and can serve as an environmentally friendly disinfectant for food, as its reactive species degrade over time, unlike traditional disinfectants.
Using a microwave plasma system (MidiPLexc) to treat deionized water, the results demonstrated that extending the treatment time significantly enhanced the bactericidal effect on biofilms. After 900 seconds of pre-treatment, subsequent PAW treatment of the biofilm for 5 minutes significantly reduced bacterial survival, with CFU decreasing by 3.1 log10, cell metabolic activity declining by 47.9%, and cell viability dropping by 69.5%. Further microscopic analysis revealed that longer treatment times led to a significant reduction in both bacterial viability and the structural integrity of the biofilm, resulting a rougher and flattened structure. Another study utilized a surface dielectric barrier discharge (SDBD) technique to generate PAW, evaluated its effectiveness against Listeria monocytogenes in both planktonic and biofilm states. The research demonstrated that PAW generated with 36 W of discharge power and activated for 30 minutes exhibited the lowest pH and the highest concentrations of hydrogen peroxide, nitrates, and nitrites, resulting in the best inactivation of planktonic cells, achieving a 4.6 log reduction after 15 minutes of treatment. Although PAW was less effective at inactivating biofilms formed on stainless steel and polystyrene surfaces, extending the treatment time to 30 minutes led to an inactivation of over 4.5 log10. RNA-seq analysis revealed that PAW primarily affected the expression of genes related to carbon metabolism, virulence, and stress responses, with several overexpressed genes belonging to the cobalamin-dependent gene cluster.
Using a microwave plasma system (MidiPLexc) to treat deionized water, the results demonstrated that extending the treatment time significantly enhanced the bactericidal effect on biofilms. After 900 seconds of pre-treatment, subsequent PAW treatment of the biofilm for 5 minutes significantly reduced bacterial survival, with CFU decreasing by 3.1 log10, cell metabolic activity declining by 47.9%, and cell viability dropping by 69.5%. Further microscopic analysis revealed that longer treatment times led to a significant reduction in both bacterial viability and the structural integrity of the biofilm, resulting a rougher and flattened structure. Another study utilized a surface dielectric barrier discharge (SDBD) technique to generate PAW, evaluated its effectiveness against Listeria monocytogenes in both planktonic and biofilm states. The research demonstrated that PAW generated with 36 W of discharge power and activated for 30 minutes exhibited the lowest pH and the highest concentrations of hydrogen peroxide, nitrates, and nitrites, resulting in the best inactivation of planktonic cells, achieving a 4.6 log reduction after 15 minutes of treatment. Although PAW was less effective at inactivating biofilms formed on stainless steel and polystyrene surfaces, extending the treatment time to 30 minutes led to an inactivation of over 4.5 log10. RNA-seq analysis revealed that PAW primarily affected the expression of genes related to carbon metabolism, virulence, and stress responses, with several overexpressed genes belonging to the cobalamin-dependent gene cluster.