EFFECT AND MECHANISM OF ACTION OF NON-THERMAL PLASMA IN THE SURVIVAL OF Escherichia coli, Staphylococcus aureus AND Saccharomyces cerevisiae

Abstract

Non-thermal plasma (NTP) is an emerging technology of great interest because the elimination of pathogens and spoilage microorganisms and their probable use in various industrial sectors such as food and health. In this study was to evaluate the inactivation of non-thermal plasma on the survival of Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 51811 and Saccharomyces cerevisiae. Treatments of different microorganisms were conducted with cells exposed NTP generated dielectric barrier reactor (DBD) able to produce atmospheric pressure plasmas. These devices operate at 13.56 MHz and are driven by a specifically built radio frequency (RF) resonant converter. The reactors, which operate at atmospheric pressure in a He-air gas mixture at a 1.5 L min-1 flow rate, applying a 850 V voltage at different exposure times (10, 20, 40, 60, 80, 100 and 120 s). All the strains showed a reduction in viability of < 0.001 log CFU mL-1 after to exposed to plasma. The cells showed membrane damage, these effects being the main cause for microbial inactivation, caused by the action of Non-thermal plasma, which leads to membrane and/or cell wall breakdown with consecutive DNA denaturation, these being the main factors inducing microorganism death.