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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

Kinetics for B. subtilis endospores inoculated on glass petri-dishes for (A) pure argon with (△) inactivation and ()endospore DNA damage ratio, (B) argon + 0.135% vol. oxygen with () inactivation and ()endospore DNA damage ratio, (C) argon + 0.135% vol. oxygen + 0.2% vol. nitrogen with () inactivation and () endospore DNA damage ratio. Solid lines represent the biphasic fit for the DNA damage and the dashed lines for endospore inactivation.
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Figure 3: Kinetics for B. subtilis endospores inoculated on glass petri-dishes for (A) pure argon with (△) inactivation and ()endospore DNA damage ratio, (B) argon + 0.135% vol. oxygen with () inactivation and ()endospore DNA damage ratio, (C) argon + 0.135% vol. oxygen + 0.2% vol. nitrogen with () inactivation and () endospore DNA damage ratio. Solid lines represent the biphasic fit for the DNA damage and the dashed lines for endospore inactivation.

Mentions: In case of CAPP treated peppercorns no assessment of DNA damage was conducted. Peppercorns are often highly spoiled with microorganisms. Even though they can be sterilized, the DNA material of the native microbial load is still present on the peppercorns surface and would falsify the results. For a better comparison between the inactivation and DNA damage ratio, only inactivation data of samples, which were also used for the analyzing of the DNA damage, were considered for the depiction of the inactivation behavior. Thus the inactivation kinetics shown in Figures 3 and 4 may differ slightly from those shown in Figure 2. The DNA damage ratio values were also modeled using the biphasic equation (Cerf, 1977) to investigate if the damage of the B. subtilis DNA during the CAPP showed a similar course as the corresponding inactivation kinetics. Furthermore, the point of inflection (PI) of the biphasic kinetics (inactivation and DNA damage) was calculated, which describe the transition between the first and the second phase and can be calculated as the point of intersection between the two linear phases.


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)

Kinetics for B. subtilis endospores inoculated on glass petri-dishes for (A) pure argon with (△) inactivation and ()endospore DNA damage ratio, (B) argon + 0.135% vol. oxygen with () inactivation and ()endospore DNA damage ratio, (C) argon + 0.135% vol. oxygen + 0.2% vol. nitrogen with () inactivation and () endospore DNA damage ratio. Solid lines represent the biphasic fit for the DNA damage and the dashed lines for endospore inactivation.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 3: Kinetics for B. subtilis endospores inoculated on glass petri-dishes for (A) pure argon with (△) inactivation and ()endospore DNA damage ratio, (B) argon + 0.135% vol. oxygen with () inactivation and ()endospore DNA damage ratio, (C) argon + 0.135% vol. oxygen + 0.2% vol. nitrogen with () inactivation and () endospore DNA damage ratio. Solid lines represent the biphasic fit for the DNA damage and the dashed lines for endospore inactivation.
Mentions: In case of CAPP treated peppercorns no assessment of DNA damage was conducted. Peppercorns are often highly spoiled with microorganisms. Even though they can be sterilized, the DNA material of the native microbial load is still present on the peppercorns surface and would falsify the results. For a better comparison between the inactivation and DNA damage ratio, only inactivation data of samples, which were also used for the analyzing of the DNA damage, were considered for the depiction of the inactivation behavior. Thus the inactivation kinetics shown in Figures 3 and 4 may differ slightly from those shown in Figure 2. The DNA damage ratio values were also modeled using the biphasic equation (Cerf, 1977) to investigate if the damage of the B. subtilis DNA during the CAPP showed a similar course as the corresponding inactivation kinetics. Furthermore, the point of inflection (PI) of the biphasic kinetics (inactivation and DNA damage) was calculated, which describe the transition between the first and the second phase and can be calculated as the point of intersection between the two linear phases.

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