Limits...
Impact of surface structure and feed gas composition on Bacillus subtilis endospore inactivation during direct plasma treatment.

Hertwig C, Steins V, Reineke K, Rademacher A, Klocke M, Rauh C, Schlüter O - Front Microbiol (2015)

Bottom Line: Similar maximum inactivation results were achieved for the three feed gas compositions.The surface structure had a significant impact on the inactivation efficiency of the plasma treatment.These findings indicate the significant role of VUV and UV photons in the inactivation process of B. subtilis endospores.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institute for Agricultural Engineering Potsdam-Bornim, Germany.

ABSTRACT
This study investigated the inactivation efficiency of cold atmospheric pressure plasma treatment on Bacillus subtilis endospores dependent on the used feed gas composition and on the surface, the endospores were attached on. Glass petri-dishes, glass beads, and peppercorns were inoculated with the same endospore density and treated with a radio frequency plasma jet. Generated reactive species were detected using optical emission spectroscopy. A quantitative polymerase chain reaction (qPCR) based ratio detection system was established to monitor the DNA damage during the plasma treatment. Argon + 0.135% vol. oxygen + 0.2% vol. nitrogen as feed gas emitted the highest amounts of UV-C photons and considerable amount of reactive oxygen and nitrogen species. Plasma generated with argon + 0.135% vol. oxygen was characterized by the highest emission of reactive oxygen species (ROS), whereas the UV-C emission was negligible. The use of pure argon showed a negligible emission of UV photons and atomic oxygen, however, the emission of vacuum (V)UV photons was assumed. Similar maximum inactivation results were achieved for the three feed gas compositions. The surface structure had a significant impact on the inactivation efficiency of the plasma treatment. The maximum inactivation achieved was between 2.4 and 2.8 log10 on glass petri-dishes and 3.9 to 4.6 log10 on glass beads. The treatment of peppercorns resulted in an inactivation lower than 1.0 log10. qPCR results showed a significant DNA damage for all gas compositions. Pure argon showed the highest results for the DNA damage ratio values, followed by argon + 0.135% vol. oxygen + 0.2% vol. nitrogen. In case of argon + 0.135% vol. oxygen the inactivation seems to be dominated by the action of ROS. These findings indicate the significant role of VUV and UV photons in the inactivation process of B. subtilis endospores.

No MeSH data available.


Related in: MedlinePlus

Emission spectra for pure argon (dotted black line), argon + 0.135% vol. oxygen (dashed red line) and argon + 0.135% vol. oxygen + 0.2% vol. nitrogen (solid blue line) for wavelength from (A) 180–280 nm (UV-C light), (B) 280–320 nm (UV-B light), (C) 320–400 nm (UV-A light), and (D) 775–780 nm (atomic oxygen emission).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4526801&req=5

Figure 1: Emission spectra for pure argon (dotted black line), argon + 0.135% vol. oxygen (dashed red line) and argon + 0.135% vol. oxygen + 0.2% vol. nitrogen (solid blue line) for wavelength from (A) 180–280 nm (UV-C light), (B) 280–320 nm (UV-B light), (C) 320–400 nm (UV-A light), and (D) 775–780 nm (atomic oxygen emission).

Mentions: Three different feed gas compositions (1. pure argon, 2. argon + 0.135% vol. oxygen and 3. argon + 0.135% vol. oxygen + 0.2% vol. nitrogen) were used for detailed investigation of the involved inactivation mechanisms. Reineke et al. (2015) systematically investigated the emission intensity of argon plasma with the admixture of different oxygen and nitrogen concentration and showed that plasma running with argon + 0.135% vol. oxygen emitted a high amount of reactive oxygen species (ROS), whereas plasma running with argon + 0.135% vol. oxygen + 0.2% vol. nitrogen was characterized by the highest emission of UV-C photons. The emission spectra of the used plasmas, generated with the chosen gas compositions, are shown in Figure 1. The addition of oxygen and nitrogen causes significant changes in the emission spectra. In case of pure argon, molecular bands of oxygen, nitrogen, and other species were also detected due to interactions of the argon plasma with the surrounding air. The use of argon + 0.135% vol. oxygen + 0.2% vol. nitrogen resulted in considerable emission in the UV-C range (Figure 1A), whereas the emission of UV-C photons was negligible for the two other feed gas compositions. Figure 1B shows the emission intensity of the UV-B range, which was dominated by the signal of OH radicals with the maximum of 309 nm. The addition of oxygen and nitrogen resulted in no significant changes in the emission intensity of OH radicals. The emission spectrum from 320 to 400 nm (UV-A, Figure 1C) is dominated by molecular bands of the second positive system of N2. The emissions for pure argon and argon + 0.135% vol. oxygen were negligible comparing to the use of argon + 0.135% vol. oxygen + 0.2% vol. nitrogen. Figure 1D shows the emission intensity from 775 to 780 nm, this wavelength range is characterized by the atomic oxygen band at 777 nm, and depicts considerable variations depending on the gas composition. The feed gas composition argon + 0.135% vol. oxygen emitted the highest photon intensity.


Impact of surface structure and feed gas composition on Bacillus subtilis endospore inactivation during direct plasma treatment.

Hertwig C, Steins V, Reineke K, Rademacher A, Klocke M, Rauh C, Schlüter O - Front Microbiol (2015)

Emission spectra for pure argon (dotted black line), argon + 0.135% vol. oxygen (dashed red line) and argon + 0.135% vol. oxygen + 0.2% vol. nitrogen (solid blue line) for wavelength from (A) 180–280 nm (UV-C light), (B) 280–320 nm (UV-B light), (C) 320–400 nm (UV-A light), and (D) 775–780 nm (atomic oxygen emission).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4526801&req=5

Figure 1: Emission spectra for pure argon (dotted black line), argon + 0.135% vol. oxygen (dashed red line) and argon + 0.135% vol. oxygen + 0.2% vol. nitrogen (solid blue line) for wavelength from (A) 180–280 nm (UV-C light), (B) 280–320 nm (UV-B light), (C) 320–400 nm (UV-A light), and (D) 775–780 nm (atomic oxygen emission).
Mentions: Three different feed gas compositions (1. pure argon, 2. argon + 0.135% vol. oxygen and 3. argon + 0.135% vol. oxygen + 0.2% vol. nitrogen) were used for detailed investigation of the involved inactivation mechanisms. Reineke et al. (2015) systematically investigated the emission intensity of argon plasma with the admixture of different oxygen and nitrogen concentration and showed that plasma running with argon + 0.135% vol. oxygen emitted a high amount of reactive oxygen species (ROS), whereas plasma running with argon + 0.135% vol. oxygen + 0.2% vol. nitrogen was characterized by the highest emission of UV-C photons. The emission spectra of the used plasmas, generated with the chosen gas compositions, are shown in Figure 1. The addition of oxygen and nitrogen causes significant changes in the emission spectra. In case of pure argon, molecular bands of oxygen, nitrogen, and other species were also detected due to interactions of the argon plasma with the surrounding air. The use of argon + 0.135% vol. oxygen + 0.2% vol. nitrogen resulted in considerable emission in the UV-C range (Figure 1A), whereas the emission of UV-C photons was negligible for the two other feed gas compositions. Figure 1B shows the emission intensity of the UV-B range, which was dominated by the signal of OH radicals with the maximum of 309 nm. The addition of oxygen and nitrogen resulted in no significant changes in the emission intensity of OH radicals. The emission spectrum from 320 to 400 nm (UV-A, Figure 1C) is dominated by molecular bands of the second positive system of N2. The emissions for pure argon and argon + 0.135% vol. oxygen were negligible comparing to the use of argon + 0.135% vol. oxygen + 0.2% vol. nitrogen. Figure 1D shows the emission intensity from 775 to 780 nm, this wavelength range is characterized by the atomic oxygen band at 777 nm, and depicts considerable variations depending on the gas composition. The feed gas composition argon + 0.135% vol. oxygen emitted the highest photon intensity.

Bottom Line: Similar maximum inactivation results were achieved for the three feed gas compositions.The surface structure had a significant impact on the inactivation efficiency of the plasma treatment.These findings indicate the significant role of VUV and UV photons in the inactivation process of B. subtilis endospores.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institute for Agricultural Engineering Potsdam-Bornim, Germany.

ABSTRACT
This study investigated the inactivation efficiency of cold atmospheric pressure plasma treatment on Bacillus subtilis endospores dependent on the used feed gas composition and on the surface, the endospores were attached on. Glass petri-dishes, glass beads, and peppercorns were inoculated with the same endospore density and treated with a radio frequency plasma jet. Generated reactive species were detected using optical emission spectroscopy. A quantitative polymerase chain reaction (qPCR) based ratio detection system was established to monitor the DNA damage during the plasma treatment. Argon + 0.135% vol. oxygen + 0.2% vol. nitrogen as feed gas emitted the highest amounts of UV-C photons and considerable amount of reactive oxygen and nitrogen species. Plasma generated with argon + 0.135% vol. oxygen was characterized by the highest emission of reactive oxygen species (ROS), whereas the UV-C emission was negligible. The use of pure argon showed a negligible emission of UV photons and atomic oxygen, however, the emission of vacuum (V)UV photons was assumed. Similar maximum inactivation results were achieved for the three feed gas compositions. The surface structure had a significant impact on the inactivation efficiency of the plasma treatment. The maximum inactivation achieved was between 2.4 and 2.8 log10 on glass petri-dishes and 3.9 to 4.6 log10 on glass beads. The treatment of peppercorns resulted in an inactivation lower than 1.0 log10. qPCR results showed a significant DNA damage for all gas compositions. Pure argon showed the highest results for the DNA damage ratio values, followed by argon + 0.135% vol. oxygen + 0.2% vol. nitrogen. In case of argon + 0.135% vol. oxygen the inactivation seems to be dominated by the action of ROS. These findings indicate the significant role of VUV and UV photons in the inactivation process of B. subtilis endospores.

No MeSH data available.


Related in: MedlinePlus