Efficiency Of Pathogenic Bacteria Inactivation By Non-thermal Plasma Activated Water

Non-thermal plasma has gradually being recognized by many scholars, because its can effectively kill presence in the air and liquid pathogens. Non-thermal plasma activated water as a new Non-thermal plasma sterilization forms, but its sterilization and disinfection mechanism are still in the preliminary stage, which requires us to study further found.Objective:Through non-thermal plasma activated water treatment of Staphylococcus aureus, Escherichia coli, Streptococcus mutans, Candida albicans and Streptococcus mutans biofilm. To study the bactericidal effect and mechanism of non-thermal plasma activated water.Material and Methods:20mL distilled water were treated for20min by a Driect-current (DC), atmospheric-pressure, Ar/O2(2%in volume) Non-thermal plasma micro-jet to create PAW. And the PAW was subsequently applied to Staphylococcus aureus, Escherichia coli, Streptococcus mutans, Candida albicans and Streptococcus mutans biofilm. The bactericidal capacity of PAW treatment was determined by the number of colony forming units (CFU) and fluorescence staining. The scanning electron microscopy (SEM) was used to evaluate the Streptococcus mutans planktonic and Streptococcus mutans biofilm surface morphological structure. Confocal laser scanning microscopy (CLSM) was used to show the bactericidal capacity of PAW treatment Streptococcus mutans biofilm. Hydrogen Peroxide Assay Kit and optical emission spectra (OES) were employed to investigate the reactive species in the PAW. The mechanism of PAW disinfection was explained and discussed in this study.Result:The results of CFU and fluorescence staining were shown that PAW can effectively kill Streptococcus mutans, Staphylococcus aureus, and Escherichia coli within20min, While, the weak bactericidal effect of PAW treatment Candida albicans and Streptococcus mutans biofilm; the scanning electron microscopy results was shown that we have successfully established a model of Streptococcus mutans biofilm; and we observed three-dimensional structure of Streptococcus mutans biofilms; at the777.2nm wavelength can be clearly observed atomic oxygen in the PAW, and3.0mg/L hydrogen peroxide. These active substances may play different roles in the sterilization process of PAW.Conclusion:Non-thermal plasma activated water has an effective bactericidal effect. Among the four test microorganisms, Candida albicans and Streptococcus mutans biofilm have the strongest resistance to Non-thermal plasma activated water. And the possible mechanism is that the combined effect of the reactive oxygen species in non-thermal plasma activated water causes the death of bacteria.