Abstract
In this work, the efficiency of inactivation of a cold argon plasma jet at atmospheric pressure (APPJ) on the basis of a low-current spark discharge into microorganisms with different characteristics of the cell walls was evaluated. Gram-negative bacteria Escherichia coli M17, gram-positive bacteria Bacillus subtilis 534 and Bacillus cereus IP 5832, and the yeast Saccharomyces cerevisiae were seeded on cultured Petri dishes. A plasma jet with an average power of 0.85 W and a flow rate of argon of 6.7 l/min was directed perpendicular to the Petri dishes with agar. The distance to the agar varied from 0.5 to 3 cm, and the treatment time varied from 5 to 300 s. The efficiency of inactivation was assessed by measuring the area of inactivation zones (where there was no growth of microorganisms). It was shown that gram-negative bacteria E. coli M17 is most susceptible to exposure to the plasma jet, and gram-positive bacteria B. cereus IP 5832 and yeast S. cerevisiae are most stable. It is established that an increase in the treatment time of plasma jets of a low-current spark allows effective inactivation of microorganisms over a much larger area.
Highlights
Investigation of properties of gas-discharge processes aimed at determining the possibility of their application for sterilization and disinfection treatment in protecting industrial materials, equipment, and electronics from biological damage and microbiologically induced corrosion has become of vital importance at present [1, 2]
We have developed a nonequilibrium plasma source operating under atmospheric pressure for generating low-temperature plasma based on plasma jets of a low-current spark discharge [10, 14] under the atmospheric pressure (Fig. 1)
To evaluate the sensitivity of microorganisms to cold argon plasma generated by low-current spark discharge plasma jets, a method was used based on measuring the diameter of the inactivation zone, which manifests itself as a clean area on a nutrient medium
Summary
Investigation of properties of gas-discharge processes aimed at determining the possibility of their application for sterilization and disinfection treatment in protecting industrial materials, equipment, and electronics from biological damage and microbiologically induced corrosion has become of vital importance at present [1, 2]. In spite of the large number of publications (see, for example, [8, 9, 12, 13]) devoted to analysis of various characteristics of discharges and the well-proven high effectiveness of application of discharges for biomedical purposes on the laboratory scale, the treatment with cold plasma under atmospheric pressure aimed at inactivation of microorganisms has not found wide application. This is primarily due to the fact that cold plasma sources require technically complicated equipment with a low economic efficiency. The effect of the distance between plasma plume and agar surface was investigated
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