The Preliminary Study On Bactericidal Mechanism Of Acidic Electrolyzed Water Combined With Ultrasound

Previous studies mainly focused on acidic electrolyzed water(AEW)on aquatic products preservation.Hence,the aim of this study was to evaluate the efficiency of AEW for Vibrio parahaemolyticus and Listeria monocytogenes,and to investigate the sanitization effect of ultrasound alone,to explore preliminary mechanism of acidic electrolyzed water combined with ultrasound.Low-concentration acidic electrolyzed water combined with low-power ultrasonicwere used for its more powerful bactericidal effect.The combination of acidic electrolyzed water and ultrasound could be a potential environmentally friendly alternative.1.The bactericidal effects of acidic electrolyzed water on foodborne pathogenic bacteriaIn this study,three kinds of acidic electrolyzed water with different concentrations were prepared.The AEW1(PH: 3.26,available chlorine concentration(ACC)27.89 mg/L),AEW2(PH: 2.51,ACC 39.34 mg/L),AEW3(PH: 2.13,ACC 50.93 mg/L)were produced by 0.1% concentration of NaCl in different treatment time(5min,10 min,15min).Here,we investigated the tolerance of L.monocytogenes and V.parahaemolyticus to acidic electrolyzed water(AEW)by plate counting with non-selective medium(TSA),selective medium(TCBS or PALCAM),verifying changes in bacterial morphology by scanning electron microscopy and transmission electron microscopy.It was found that AEW itself has a low bactericidal effect on L.monocytogenes.However,V.parahaemolyticus is sensitive to high concentration of acidic electrolyzed water(AEW3),and there is no sublethal cells after AEW3 treatment.SEM and TEM observed that the cell wall surface was seriously damaged,the bacterial core saccharide damage was serious,and the intracellular material flowed out,showing the strong bactericidal power of acidic electrolyzed water.2.Determination of injury sites in acidic electrolyzed water-treated cellsThrough the preliminary comparison of the bactericidal effect of V.parahaemolyticus and L.monocytogenes.We evaluated the sites of cellular damage,four kinds of metabolic inhibitors,penicillin G,rifampin,chloramphenicol,and nalidixic acid,were utilized.Howevwr,the inhibition of protein synthesis was the strongest.The AEW's destruction of V.parahaemolyticus was observed by fluorescence microscope,and the cell death state was visually analyzed.When the water concentration was AEW2,the number of dead cells in PI staining increased significantly,and the SYTO9 staining showed that the total number of bacteria including dead bacteria was greatly reduced.3.Preliminary comparison of different Ultrasound wave effectWe Studied the effects of different ultrasonic power(50w,100 w,200w)on V.parahaemolyticus.The results showed that the ultrasonic wave can disperse the bacteria very well.When the ultrasonic power is 50 w,the number of V.parahaemolyticus is reduced by 0.63 log CFU/ml,and the sublethal damage is 0.05 log CFU/mL.However,the ultrasonic power is 200 w.The sublethal damage amount is as high as 1.56 log CFU/mL,which is much higher than the sublethal of 50 w ultrasonic power.SEM and protein leakage experiments show that membrane damage is serious.ultrasonic treatment can increase the surface area of liquid contact with microorganisms,which providing a theoretical basis for the combination of acidic electrolyzed water and ultrasound 4.The preliminary exploration of bactericidal mechanism of acidic electrolyzed water combined with ultrasoundThe newly developed method of AEW+ultrasound,which was applied in food-borne pathogens,is an preliminary exploration of bactericidal mechanism of acidic electrolyzed water combined with ultrasound.The results revealed that AEW combined with ultrasonic showed that better bacterial reduction in V.parahaemolyticus of 2.09 log CFU/mL and the sub-lethal bacterial reduction was 1.80 log CFU/mL.When compared with acidic electrolyzed water or ultrasound alone.The combination of acidic electrolyzed water and ultrasound could be an new technology reduce the risk of food-borne pathogens.Similarly,the chemical bonds between the peptidoglycans of the cell wall are broken,and the proteins and lipids are damaged with the bactericidal treatment by Raman spectroscopy,.Flow analysis revealed that the biological characteristics of the cells changed significantly after the combined treatment.Therefore,the preliminary investigation of the mechanism of acidic electrolyzed water combined with ultrasonic wave provides a theoretical basis for the microbial safety of the sterilization technology in the food field.