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

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 degrees 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.