Inactivation of Bacillus Subtilis by Atomic Oxygen Radical Anion

Abstract

UAtomic oxygen radical anion (O−) is one of the most activeoxygen species, and has extremely high oxidation ability towardsmall-molecules of hydrocarbons. However, to our knowledge, littleis known about the effects of O− on cells of micro-organisms.This work showed that O− could quickly react with the Bacillussubtilis cells and seriously damage the cell walls a s well as theirother contents, leading to a fast and irreversible inactivation. SEM micrographs revealed that the cell structures were dramatically destroyed by their exposure to O−. The inactivation efficiencies of B. subtilis depend on the O−intensity, the initial population of cells and the treatmenttemperature, but not on the pH in the range of our investigation.For a cell concentration of 106 cfu/ml, the number of survivedcells dropped from 106 cfu/ml to 103 cfu/ml after aboutfive-minute irradiation by an O− flux in an intensity of 233nA/cm2 under a dry argon environment (30 oC, 1 atm,exposed size: 1.8 cm2). The inactivation mechanism ofmicro-organisms induced by O− is also discussed.