Sterilization of Staphylococcus aureus microorganism using a novel cold plasma technology

Atmospheric plasmas generated by electrical discharges have been used for bio-medical and environmental purposes such as air pollution control, wastewater cleaning, bio-decontamination and surface sterilization, treatment of skin diseases, etc. Pathogenic bacteria are microorganisms which may cause food poisoning, gastroenteritis, bacteremia, skin diseases, and pneumonia, and their control is critical in environments such as food processing plants or hospitals. Therefore, the objective of this study is to determine the best exposure time of the non-thermal plasma to inhibit or kill bacteria on solid surfaces and the inhibitory effect of the plasma treatment on bacterial growth. Staphylococcus aureus, commonly found on hospitals, have been tested. S. aureus  ATCC 25923 was incubated on agar plates and treated with the plasma at different exposure times (30, 60, 120 and 180 seconds), after incubation, colonies were quantified. The survival colonies after 60 seconds of treatment and the control colonies were transferred to tryptic soy broth (TSB) to determine the inhibitory effect on bacterial growth. Optical density (O.D.) and a bacterial concentration (CFU/ml) were recorded to determine the bacterial growth. Results of the experiment demonstrated that the longer the exposure time, the more the bacterial growth is inhibited. The most efficient time of the plasma exposure for complete elimination of S. aureus was 180 seconds. Preliminary results have suggested that there is no effect on bacterial growth of the survival colonies after the treatment. These results suggested the potential use of the non-thermal plasma on the bacterial elimination at the appropriate exposure time.