Comparison of pulsed corona plasma and pulsed electric fields for the decontamination of water containing Legionella pneumophila as model organism.
Pulsed corona plasma and pulsed electric fields were assessed for their capacity to kill Legionella pneumophila in water. Electrical parameters such as in particular dissipated energy were equal for both treatments. This was accomplished by changing the polarity of the applied high voltage pulses in a coaxial electrode geometry resulting in the generation of corona plasma or an electric field. For corona plasma, generated by high voltage pulses with peak voltages of +80kV, Legionella were completely killed, corresponding to a log-reduction of 5.4 (CFU/ml) after a treatment time of 12.5min. For the application of pulsed electric fields from peak voltages of -80kV a survival of log 2.54 (CFU/ml) was still detectable after this treatment time. Scanning electron microscopy images of L. pneumophila showed rupture of cells after plasma treatment. In contrast, the morphology of bacteria seems to be intact after application of pulsed electric fields. The more efficient killing for the same energy input observed for pulsed corona plasma is likely due to induced chemical processes and the generation of reactive species as indicated by the evolution of hydrogen peroxide. This suggests that the higher efficacy and efficiency of pulsed corona plasma is primarily associated with the combined effect of the applied electric fields and the promoted reaction chemistry.
Leibniz Institute for Plasma Science and Technology e.V. (INP Greifswald), Felix-Hausdorff-Straße 2, 17489 Greifswald, Germany.
Robert
R
Banaschik
Department Genetics of Microorganisms, Interfaculty Institute for Genetics and Functional Genomics, Ernst Moritz Arndt University of Greifswald, Friedrich-Ludwig-Jahn-Straße 15a, 17489 Greifswald, Germany.
Gerhard
G
Burchhardt
Leibniz Institute for Plasma Science and Technology e.V. (INP Greifswald), Felix-Hausdorff-Straße 2, 17489 Greifswald, Germany.
Katja
K
Zocher
Department Genetics of Microorganisms, Interfaculty Institute for Genetics and Functional Genomics, Ernst Moritz Arndt University of Greifswald, Friedrich-Ludwig-Jahn-Straße 15a, 17489 Greifswald, Germany. Electronic address: sven.hammerschmidt@uni-greifswald.de.
Sven
S
Hammerschmidt
Leibniz Institute for Plasma Science and Technology e.V. (INP Greifswald), Felix-Hausdorff-Straße 2, 17489 Greifswald, Germany. Electronic address: juergen.kolb@inp-greifswald.de.
Juergen F
JF
Kolb
Leibniz Institute for Plasma Science and Technology e.V. (INP Greifswald), Felix-Hausdorff-Straße 2, 17489 Greifswald, Germany.
Klaus-Dieter
KD
Weltmann
D003666:Decontamination / Q000379:methods*; D004560:Electricity; D016952:Legionella pneumophila / Q000187:drug effects* / Q000302:isolation & purification; D058626:Plasma Gases / Q000494:pharmacology*; D014871:Water Microbiology
D058626:Plasma Gases
Bacterial killing; Decontamination; Legionella pneumophila; Non-thermal plasma; Pulsed electric fields