Sterilization effect of atmospheric plasma on Escherichia coli and Bacillus subtilis endospores

Abstract

Aims: Escherichia coli and Bacillus subtilis spores were treated with an atmospheric plasma mixture created by the ionization of helium and oxygen to investigate the inactivation efficiency of a low-temperature plasma below 70°C. Methods and results: An electrical discharge plasma was produced at a radio frequency (RF) of 13·56 MHz, connected to a perforated circular electrode with a discharge spacing of 1-15 mm. The discharge gas was helium with 0-2% oxygen. For the plasma treatment, a dried E. coli cell or B. subtilis endospore suspension on a cover-glass was exposed to oxygen downstream of the plasma from holes in an RF-powered electrode. The sterilization effect of the RF plasma was highest with 0·2% oxygen, corresponding to the maximum production of oxygen radicals. Conclusions: Oxygen radicals generated by RF plasma are effective for the destruction of bacterial cells and endospores. Significance and Impact of the study: Low-temperature atmospheric plasma can be used for the disinfection of diverse objects, especially for the inactivation of bacterial endospores. © 2008 The Society for Applied Microbiology.