Probing bactericidal mechanisms induced by cold atmospheric plasmas with Escherichia coli mutants

Abstract

Mechanisms of plasma-induced microbial inactivation have commonly been studied with physicochemical techniques. In this letter, Escherichia coli K-12 and its ΔrecA, ΔrpoS, and ΔsoxS mutants are employed to discriminate effects of UV photons, OH radicals, and reactive oxygen species produced in atmospheric discharges. This microbiological approach exploits the fact that these E. coli mutants are defective in their resistance against various external stresses. By interplaying bacterial inactivation kinetics with optical emission spectroscopy, oxygen atoms are identified as a major contributor in plasma inactivation with minor contributions from UV photons, OH radicals, singlet oxygen metastables, and nitric oxide.

Cold atmospheric plasma manipulation of proteins in food systems

“…1). The minor roles of UV photons and positive or negative particles may also play a part (Perni et al, 2007). ROS---for instance superoxide radicals or hydroxyl radicals---seems to be the main contributor to the plasma antibacterial activity (Boudam et al, 2006;Gaunt et al, 2006 (Berlett and Stadtman, 1997).…”

Plasmas meet nanoparticles—where synergies can advance the frontier of medicine

“…This can filter out the effects of some ROS/RNS, since their concentrations at the cell/tissue location may fall below the threshold of their biological effects. For example, current evidence of bacterial inactivation studies suggests that UV photons play a less important role than ROS [92]- [94]. Figure 2 shows a damaged membrane of B. subtilis spores after plasma treatment, typical of a result of oxidation.…”

“…Studies using isolated protein and plasmid DNA models have shown protein and DNA damages [95]- [99], and more relevant experiments using bacterial cells have provided direct evidence of breaching and rapture of cell membrane [100], reduction and degradation of proteins [101]- [103], lipid damage [104], and (mostly) single-strand breaks (SSB) of DNA [105]. These results have prompted the suggestion of the involvement of ROS, charged particles, and UV photons [92][100] [105] - [108], with ROS often linked to oxidation of protein and lipid and with UV photons linked to DNA damages. The view of DNA damages, particularly double-strand breaks (DSB), being largely induced by UV and shorter-wavelength radiation has its root in radiation biology where many hundreds of DSBs per microorganism are not uncommon among irradiated bacteria [109].…”

Study on Surface Properties of Polyamide 66 Using Atmospheric Glow-Like Discharge Plasma Treatment

“…The high-energy electrons, ions, other active particles and the ultraviolet rays during the discharge have, to some extent, an inactivation effect on the microorganisms [28]. This kind of inactivation effect is achieved by their damage on the cytomembrane, cytoderm and the genetic material.…”