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Deterioration to extinction of wastewater bacteria by non-thermal atmospheric pressure air plasma as assessed by 16S rDNA-DGGE fingerprinting.

El-Sayed WS, Ouf SA, Mohamed AA - Front Microbiol (2015)

Bottom Line: Conversely, all bacterial groups were completely eliminated by treatment at 85.34 mA for either 60 or 90 s.The same trend was observed for treatment at 81.94 mA.The variability in bacterial community response to different plasma treatment protocols revealed that plasma had a selective impact on bacterial community structure at lower doses and potential bactericidal effects at higher doses.

View Article: PubMed Central - PubMed

Affiliation: Biology Department, Faculty of Science, Taibah University Almadinah Almunawarah, Saudi Arabia ; Microbiology Department, Faculty of Science, Ain Shams University Cairo, Egypt.

ABSTRACT
The use of cold plasma jets for inactivation of a variety of microorganisms has recently been evaluated via culture-based methods. Accordingly, elucidation of the role of cold plasma in decontamination would be inaccurate because most microbial populations within a system remain unexplored owing to the high amount of yet uncultured bacteria. The impact of cold atmospheric plasma on the bacterial community structure of wastewater from two different industries was investigated by metagenomic-based polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) utilizing 16S rRNA genes. Three doses of atmospheric pressure dielectric barrier discharge plasma were applied to wastewater samples on different time scales. DGGE revealed that the bacterial community gradually changed and overall abundance decreased to extinction upon plasma treatment. The bacterial community in food processing wastewater contained 11 key operational taxonomic units that remained almost completely unchanged when exposed to plasma irradiation at 75.5 mA for 30 or 60 s. However, when exposure time was extended to 90 s, only Escherichia coli, Coliforms, Aeromonas sp., Vibrio sp., and Pseudomonas putida survived. Only E. coli, Aeromonas sp., Vibrio sp., and P. putida survived treatment at 81.94 mA for 90 s. Conversely, all bacterial groups were completely eliminated by treatment at 85.34 mA for either 60 or 90 s. Dominant bacterial groups in leather processing wastewater also changed greatly upon exposure to plasma at 75.5 mA for 30 or 60 s, with Enterobacter aerogenes, Klebsiella sp., Pseudomonas stutzeri, and Acidithiobacillus ferrooxidans being sensitive to and eliminated from the community. At 90 s of exposure, all groups were affected except for Pseudomonas sp. and Citrobacter freundii. The same trend was observed for treatment at 81.94 mA. The variability in bacterial community response to different plasma treatment protocols revealed that plasma had a selective impact on bacterial community structure at lower doses and potential bactericidal effects at higher doses.

No MeSH data available.


Related in: MedlinePlus

Emission spectra of atmospheric pressure DBD plasma at 70 mA peak to peak current in the range of 200 to 850 nm. (A) Spectra were normalized to the highest peak of the N2 second positive system 0–0 transition (337.2 nm). (B) Represents magnified scale to show the existence of nitric oxide (NO) species.
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Figure 3: Emission spectra of atmospheric pressure DBD plasma at 70 mA peak to peak current in the range of 200 to 850 nm. (A) Spectra were normalized to the highest peak of the N2 second positive system 0–0 transition (337.2 nm). (B) Represents magnified scale to show the existence of nitric oxide (NO) species.

Mentions: The DBD plasma emission spectra between 200 and 850 nm revealed the presence of nitrogen molecules (N2) (Figure 3A). The maximum intensity of the spectra of the nitrogen molecule second positive system (C3Πu → B3Πg) in UV was observed at its 0–0 transition (337.2 nm). Therefore, the total spectra were normalized with respect to the nitrogen molecule (N2) second positive system (C3Πu → B3Πg) 0–0 transition intensity. The emission spectra of the N2+ first negative system (B2 Σu+ → X3Σg+) were measured at 391 nm, indicating the presence of a high electron temperature in the generated DBD plasma. Moreover, the Nitric oxide (NO) radical emission spectra increased with higher DBD current values (Figure 3B). NO and N2+ production increased with increasing discharge current (Figures 4A,B). The existence of the N2+ first negative system and NO radical showed a high level of non-equilibrium in the generated plasma (non-thermal). The presence of high electron temperature electrons (energetic) initiates dissociation and ionization, which are essential in bio-decontamination. The increase in the emission spectra of the NO and N2+ first negative system indicates an increase in their contribution to the decontamination with increasing DBD current.


Deterioration to extinction of wastewater bacteria by non-thermal atmospheric pressure air plasma as assessed by 16S rDNA-DGGE fingerprinting.

El-Sayed WS, Ouf SA, Mohamed AA - Front Microbiol (2015)

Emission spectra of atmospheric pressure DBD plasma at 70 mA peak to peak current in the range of 200 to 850 nm. (A) Spectra were normalized to the highest peak of the N2 second positive system 0–0 transition (337.2 nm). (B) Represents magnified scale to show the existence of nitric oxide (NO) species.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4594161&req=5

Figure 3: Emission spectra of atmospheric pressure DBD plasma at 70 mA peak to peak current in the range of 200 to 850 nm. (A) Spectra were normalized to the highest peak of the N2 second positive system 0–0 transition (337.2 nm). (B) Represents magnified scale to show the existence of nitric oxide (NO) species.
Mentions: The DBD plasma emission spectra between 200 and 850 nm revealed the presence of nitrogen molecules (N2) (Figure 3A). The maximum intensity of the spectra of the nitrogen molecule second positive system (C3Πu → B3Πg) in UV was observed at its 0–0 transition (337.2 nm). Therefore, the total spectra were normalized with respect to the nitrogen molecule (N2) second positive system (C3Πu → B3Πg) 0–0 transition intensity. The emission spectra of the N2+ first negative system (B2 Σu+ → X3Σg+) were measured at 391 nm, indicating the presence of a high electron temperature in the generated DBD plasma. Moreover, the Nitric oxide (NO) radical emission spectra increased with higher DBD current values (Figure 3B). NO and N2+ production increased with increasing discharge current (Figures 4A,B). The existence of the N2+ first negative system and NO radical showed a high level of non-equilibrium in the generated plasma (non-thermal). The presence of high electron temperature electrons (energetic) initiates dissociation and ionization, which are essential in bio-decontamination. The increase in the emission spectra of the NO and N2+ first negative system indicates an increase in their contribution to the decontamination with increasing DBD current.

Bottom Line: Conversely, all bacterial groups were completely eliminated by treatment at 85.34 mA for either 60 or 90 s.The same trend was observed for treatment at 81.94 mA.The variability in bacterial community response to different plasma treatment protocols revealed that plasma had a selective impact on bacterial community structure at lower doses and potential bactericidal effects at higher doses.

View Article: PubMed Central - PubMed

Affiliation: Biology Department, Faculty of Science, Taibah University Almadinah Almunawarah, Saudi Arabia ; Microbiology Department, Faculty of Science, Ain Shams University Cairo, Egypt.

ABSTRACT
The use of cold plasma jets for inactivation of a variety of microorganisms has recently been evaluated via culture-based methods. Accordingly, elucidation of the role of cold plasma in decontamination would be inaccurate because most microbial populations within a system remain unexplored owing to the high amount of yet uncultured bacteria. The impact of cold atmospheric plasma on the bacterial community structure of wastewater from two different industries was investigated by metagenomic-based polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) utilizing 16S rRNA genes. Three doses of atmospheric pressure dielectric barrier discharge plasma were applied to wastewater samples on different time scales. DGGE revealed that the bacterial community gradually changed and overall abundance decreased to extinction upon plasma treatment. The bacterial community in food processing wastewater contained 11 key operational taxonomic units that remained almost completely unchanged when exposed to plasma irradiation at 75.5 mA for 30 or 60 s. However, when exposure time was extended to 90 s, only Escherichia coli, Coliforms, Aeromonas sp., Vibrio sp., and Pseudomonas putida survived. Only E. coli, Aeromonas sp., Vibrio sp., and P. putida survived treatment at 81.94 mA for 90 s. Conversely, all bacterial groups were completely eliminated by treatment at 85.34 mA for either 60 or 90 s. Dominant bacterial groups in leather processing wastewater also changed greatly upon exposure to plasma at 75.5 mA for 30 or 60 s, with Enterobacter aerogenes, Klebsiella sp., Pseudomonas stutzeri, and Acidithiobacillus ferrooxidans being sensitive to and eliminated from the community. At 90 s of exposure, all groups were affected except for Pseudomonas sp. and Citrobacter freundii. The same trend was observed for treatment at 81.94 mA. The variability in bacterial community response to different plasma treatment protocols revealed that plasma had a selective impact on bacterial community structure at lower doses and potential bactericidal effects at higher doses.

No MeSH data available.


Related in: MedlinePlus