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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

Inactivation kinetics for Bacillus subtilis endospores for (△) pure argon, () argon + 0.135% vol. oxygen, () argon + 0.135% vol. oxygen + 0.2% vol. nitrogen inoculated on: (A) glass petri-dishes, (B) glass beads and (C) peppercorns, with biphasic fit.
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Figure 2: Inactivation kinetics for Bacillus subtilis endospores for (△) pure argon, () argon + 0.135% vol. oxygen, () argon + 0.135% vol. oxygen + 0.2% vol. nitrogen inoculated on: (A) glass petri-dishes, (B) glass beads and (C) peppercorns, with biphasic fit.

Mentions: To ensure comparable results between the three surfaces, all samples were inoculated with equal endospore densities of B. subtilis endospores. The obtained inactivation data were modeled using a biphasic inactivation model, which adequately described the inactivation behavior (Table 2). The resulting inactivation kinetics are shown in Figure 2. All inactivation kinetics showed an accelerated initial followed by a retarded inactivation for longer plasma exposure times, which can be also seen by inactivation rate constants (k). In general the k1 (first inactivation phase) were higher than the k2 (second inactivation phase) values. For each treated surface, the achieved maximum inactivation levels were relatively close together independent of the used feed gas composition. Nevertheless, the use of pure argon as feed gas for all three different surfaces resulted in the highest inactivation level, whereas the lowest inactivation was achieved by CAPP running with argon + 0.135% vol. oxygen in all cases.


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)

Inactivation kinetics for Bacillus subtilis endospores for (△) pure argon, () argon + 0.135% vol. oxygen, () argon + 0.135% vol. oxygen + 0.2% vol. nitrogen inoculated on: (A) glass petri-dishes, (B) glass beads and (C) peppercorns, with biphasic fit.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 2: Inactivation kinetics for Bacillus subtilis endospores for (△) pure argon, () argon + 0.135% vol. oxygen, () argon + 0.135% vol. oxygen + 0.2% vol. nitrogen inoculated on: (A) glass petri-dishes, (B) glass beads and (C) peppercorns, with biphasic fit.
Mentions: To ensure comparable results between the three surfaces, all samples were inoculated with equal endospore densities of B. subtilis endospores. The obtained inactivation data were modeled using a biphasic inactivation model, which adequately described the inactivation behavior (Table 2). The resulting inactivation kinetics are shown in Figure 2. All inactivation kinetics showed an accelerated initial followed by a retarded inactivation for longer plasma exposure times, which can be also seen by inactivation rate constants (k). In general the k1 (first inactivation phase) were higher than the k2 (second inactivation phase) values. For each treated surface, the achieved maximum inactivation levels were relatively close together independent of the used feed gas composition. Nevertheless, the use of pure argon as feed gas for all three different surfaces resulted in the highest inactivation level, whereas the lowest inactivation was achieved by CAPP running with argon + 0.135% vol. oxygen in all cases.

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