The Effect of Cold Plasma on Inactivation and Growth of Staphylococcus aureus, Pseudomonas aerunginosa, Salmonella Typhimurium and Bacillus cereus for Food Industry and Medical Applications

The cold plasma is proposed as an alternative method for food, medical devices and human skin decontamination. The goal of this study is to determine the best exposure time of the cold plasma to inactivate selected pathogenic bacteria and its effect on bacterial growth. Staphylococcus aureus ATCC 25923, Pseudomonas aerunginosa ATCC 27853, Salmonella enterica subesp. enterica serovar Thyphimurium ATCC 14028 and  B. cereus ATCC 14579 were exposed to plasma  on trypticase soy agar plates (TSA) and on egg shells for Salmonella, at low (15-26 CFU) and high (~10⁵ to 10⁷ CFU) concentrations, per inactivation zone. TSA and eggs shells were exposed to plasma at different times (0 s to 360 s) bacterial inactivation was recorded as percentage at low concentration and log ₁₀ reductions at high concentration. Survived colonies after 60 s and 35 s of treatment were transferred to bacterial broth to determine the effect of plasma on bacterial growth and bacterial concentrations (CFU/ml) were recorded for 24hrs. Results show for S. aureus, 96% and 2.4 log₁₀ reductions after 60 s and 360 s of treatment respectively. P. aeruginosa showed a 100% of elimination after 180 s and 3.9 log₁₀ reductions after 360 s of treatment. B. cereus was 99% inactivated after 90 s and Salmonella Typhimurium 2.9 log₁₀ reductions after 120 s, on eggs shells 0.9 log₁₀ reduction was achieved. The growth of post plasma treated colonies was not significantly affected. The potential use of the cold plasma on elimination of pathogenic bacteria is supported by these results.