Survival of vegetative pathogens under argon plasma treatments

Argon plasma sensitivities of Escherichia coli, Staphylococcus aureus and Salmonella typhimurium cells were studied by plasma treatments generated in the low gas pressure of 50 Pa. The different plasmas were induced at 2.63 and 4.21 w/cm³ microwave power densities to have the low temperature distributions below 60 °C. Certain external factors that may affect the pathogen survival under plasma processing such as the extent of bio-indicator loads and the nature of bio-indicator carriers was examined. The increase of microwave power density of the plasma treatments caused significant reductions in the pathogen survival, and thereby correlated with the increases in cell injury. Among the pathogens subjected to the plasmas, the gram-positive S. aureus cells were the most resistant and the plasma sensitivity was followed by the gram-negative E. coli and S. typhimurium cells. Survival of the E. coli cells was lower when the extent of bio-indicator loads was larger, and its survival was affected most strongly on paper followed by propylene and glass bio-indicator carriers.