Inactivation of Escherichia coli Using the Atmospheric Pressure Plasma Jet of Ar gas

Germicidal treatments of Escherichia coli on Langmuir--Blodget (LB) agar were performed using the atmospheric pressure plasma jet sources of Ar gas in the ambient air. Shorter distances from the nozzle of the plasma jet device were more effective in achieving higher bactericidal effects on E. coli g...

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Published inJapanese Journal of Applied Physics Vol. 52; no. 3; pp. 036201 - 036201-4
Main Authors Homma, Takeshi, Furuta, Masakazu, Takemura, Yuichiro
Format Journal Article
LanguageEnglish
Published The Japan Society of Applied Physics 01.03.2013
Subjects
Agar
Atmospheric pressure
Barometric pressure
Escherichia coli
Nozzles
Plasma (physics)
Radicals
Surface temperature
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Summary:Germicidal treatments of Escherichia coli on Langmuir--Blodget (LB) agar were performed using the atmospheric pressure plasma jet sources of Ar gas in the ambient air. Shorter distances from the nozzle of the plasma jet device were more effective in achieving higher bactericidal effects on E. coli grown on LB agar. The surface temperature of the agar was monitored and the spectroscopic analysis of the plasma jet was performed in order to evaluate the factors contributing to the bactericidal effect, such as heating, UV emission, and radical formation caused by the plasma jet. Although the plasma jet raised the surface temperature of LB agar up to about 40 °C, the bactericidal effect was not observed. Moreover, the bactericidal effect of UV (200--300 nm) emitted from the plasma jet was negligible compared with the effects of ions and radical species generated by the atmospheric plasma. The results suggest that the ions and radical species generated by the atmospheric pressure plasma jet are critical for high bactericidal effects on E. coli .
Bibliography:Schematic of the germicidal treatment by plasma jet, spectroscopic measurement, and thermometry. Growth inhibition of E. coli on LB agar after Ar plasma treatment [(a) untreated, (b) Ar gas only, and (c)--(e) Ar plasma-treated at distances of (c) 5, (d) 10, and (e) 15 mm from the nozzle of the plasma emission]. Relationship between the bacterial count of E. coli vs the distance from the plasma nozzle. The working gas was Ar gas, the gas flow rate was 20 l/min, the plasma exposure time was 60 s, and the distances from the nozzle were 5, 10, and 15 mm. Error bars indicate the standard deviation of 3 measured values. Temperature changes on the surface of the LB agar at various distances from the plasma nozzle. Total bacterial count of E. coli on LB agar in an incubator at 40 °C. Total bacterial count of E. coli exposed to Ar plasma jet through glass. UV/visible emission spectra of Ar plasma jet sources. UV/visible emission spectra of Ar plasma jet sources in the wavelength range from 200 to 1000 nm at various distances from nozzle. Emission spectra of Ar I and OH at various distances from nozzle.
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ISSN:0021-4922
1347-4065
DOI:10.7567/JJAP.52.036201