Sterilization effect of atmospheric plasma onEscherichia coliandBacillus subtilisendospores

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.

Bacillus subtilis devitalization mechanism of atmosphere pressure plasma jet

“…So the UV radiation generated by the plasma jet played a little role to bacterial inactivation, and which was consistent with Ref. [14].…”

“…Therefore, this result clearly indicated the temperature was not responsible for B. subtilis inactivation in our experiment, and which was consistent with Refs. [13,14]. In addition, about ten percent of the bacilli reduced after 3 min UV radiation generated by plasma jet.…”

“…Å OH (as a result of the dissociation of water molecules, present as moisture in air or plasma feed gas) considered in the bacterial inactivation playing an important role. O IV (as a result of the dissociation of oxygen molecules, present in the open air) as a kind of reactive oxygen species, also had an important effect on the bacterial inactivation [12][13][14]. N þ 2 (as a result of the Penning ionization process of N 2 molecules with the electron in plasma plume) and Ar I (as a result of exciting Ar) also could bombard and react with the bacteria.…”

“…Wintenberg et al [12] and Uhm et al [13,14] found that oxygen-containing atmospheric pressure plasmas have a profound antimicrobial influence on bacterial spores. In this paper, a dielectric barrier discharge (DBD) plasma jet using different working gas (Argon or Argon + O 2 ) was operated in the open air for inactivation.…”

Nonthermal Plasma Inactivation of Food-Borne Pathogens

“…The cell wall rupture has been additionally attributed by Laroussi et al, (2003) and Mendis et al, (2002) to electrostatic forces due to accumulation of charges at the outer surface of cell membranes. The morphological changes in E. coli cells treated with atmospheric plasma at 75W for 2 min as observed under an electron microscope by (Hong et al 2009), clearly revealed that the treated cells had severe cytoplasmic deformations and leakage of bacterial chromosome. These observations demonstrate the loss of viability of bacterial cells after plasma treatment.…”