The sterilization of E. coli (ATCC8099) using an atmospheric pressure, air DBD plasma driven by 100 Hz high-voltage power supply was investigated in this paper. The results showed that germicidal efficiency was closely related to the plasma treatment time, the gap spacing, the initial cell density and the surface characters of substrate materials. The germicidal efficiency was 99.999% under the conditions of 5-min plasma treatment, 3-cm gap spacing and on PET films. After plasma exposure for 5 min, the temperature was observed below 43 degrees C which could not lead to inactivate E. coli. The observation of protein leakage and cell morphology alteration by transmission electron microscopy (TEM) techniques revealed that the etching action on cell membrane by electrons, ions and radicals was primary reason of DBD air plasma sterilization. (C) 2011 Elsevier B.V. All rights reserved.