Low temperature oxygen plasma sterilization effect on Pseudomonas aeruginosa

Abstract:

[Objective] Low temperature oxygen plasma was used to sterilize the Pseudomonas aeruginosa samples on the polyethylene terephthalate (PET) sheets in a self-designed reactor that included the discharge area, afterglow area and remote area. [Methods] Before and after plasma treatment, the cell morphology was studied by scanning electron microscopy (SEM). The cell wall or cell membrane cracking was testified to determine the content of protein by using coomassie light blue technique. Besides, double Langmuir probe and electron spin resonance spectroscopy were used to determine the temperature of electrons (ions) and the concentration of free radicals, respectively. [Results] Under the treatment time of 30 s, the germicidal effects were 4.2, 3.8 and 2.6 respectively in the three areas. SEM observations showed that the plasma activity cracks the cell wall and cell membrane, resulting in cellular content leakage. In addition, the results from electron spin resonance spectroscopy and double Langmuir electron probe showed that electrons, ions and oxygen free radicals played important roles in sterilization in the discharge area, but only oxygen free radicals acted to sterilize the bacteria in the afterglow area and the remote area. [Conclusion] The active species can be separated effectively in this reaction equipment, and we further elucidated the mechanisms of plasma sterilization in the remote plasma field.