Low temperature air plasma sterilization on Pseudomonas aeruginosa

Low temperature air plasma was used to sterilize the Pseudomonas aeruginosa (P. aeruginosa ATCC15442) samples on the polyethylene terephthalate (PET) sheet in a self-designed reactor that included the discharge area, afterglow area and remote area. The air plasma sterilization rules in the three zones were respectively showed on the following conditions: discharge power was 60W and gas flux was 30 cm/ min. For a treatment time of 90 s, the germicidal effects (GE) were 4.01, 3.87 and 2.91. The results showed that low temperature air plasma can kill effectively P.aeruginosa in a short time and have different sterilization effects in different reactor zones. Before and after plasma treatment, scanning electron microscopy (SEM) was used to observe changes in cell morphology. The cell walls or cell membrane cracking was testified by determining the content of protein using coomassie light blue technique. The results show the plasma activity cracking the cell wall and cell membrane, and resulting in cellular content leakage. We suggest the cell membrane damage is possibly the mechanism to kill P. aeruginosa under the plasma.