Differential gene expression inEscherichia colifollowing exposure to nonthermal atmospheric pressure plasma

Abstract

Aim: Nonthermal atmospheric‐pressure plasmas offer significant advantages as an emerging disinfection approach. However the mechanisms of inactivation, and thus the means of optimizing them, are still poorly understood. The objective of this study, therefore, was to explore differential gene expression on a genome‐wide scale in Escherichia coli following exposure to a nonthermal atmospheric‐pressure argon plasma plume using high‐density oligonucleotide microarrays. Methods and Results: Plasma exposure was found to significantly induce the SOS mechanism, consisting of about 20 genes. Other genes involved in regulating response to oxidative stress were also observed to be up‐regulated. Conversely, the expression of several genes responsible for housekeeping functions, ion transport, and metabolism was observed to be down‐regulated. Conclusions: Elevated yet incomplete induction of various DNA damage repair processes, including translesion synthesis, suggests substantial DNA damage in E. coli. Oxidative stress also appeared to play a role. Thus it is proposed that the efficacy of plasma is due to the synergistic impact of UV photons and oxygen radicals on the bacteria. Significance and Impact of the Study: This study represents the first investigation of differential gene expression on a genome‐wide scale in an organism following plasma exposure. The results of this study will help enable the design of safe and effective plasma decontamination devices.

Microarray Analysis of Transcriptomic Response of <i>Escherichia coli</i> to Nonthermal Plasma-Treated PBS Solution

“…We observed highest expression of oxyS transcript ( Table 1), an indicator of a generation of severe oxidative stress, and may suggest a synergy of different reactive oxidative species that enhance inactivation of E. coli cells during plasma-activated PBS exposure. Similar observation was noted by Pruden Laboratory [6] during direct argon gas plasma application, indicating that oxidative stress is observed in both, direct plasma exposure and plasma-activated fluid. OxyS further regulates multiple targets (over a dozen genes); of which sodA is one of the major players that was upregulated in our study.…”

“…Hence it is likely that oxidative stress mediating transcriptional response by plasma-activated PBS though not completely, would be little different as compared to H 2 O 2 in type and intensity. An analysis using global gene expression approach is recently used by Dr. Pruden's Laboratory [6] using argon gas plasma (an entirely different type of plasma set up, and parameters), where an overlapping expression patterns were observed; therefore this study becomes more interesting. Our microarray data analysis suggests that selection of hydrogen peroxide as a positive control for this study was logical.…”

“…Since last decade, several publications appeared which stressed the advantages of this technique over traditional disinfection techniques [1] [2]. The direct plasma application technique is a little challenging to delicate surfaces and tissues, which are likely to be damaged by high energy electrons and UV photons generated during direct bombardment of plasma [3]- [6]. In addition, the distance between plasma generating probe and the surface being treated is critical, and determines the dose and efficacy of plasma.…”

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

“…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].…”

Emerging applications of low temperature gas plasmas in the food industry

“…71 A recent review by Lackman and Bandow paints a far more complex picture involving not only disruption of the cell membrane but also etching of the cell wall, DNA damage, RNA strand breaks and oxidative damage to proteins. 72 Although reactive plasma species can interact with biomolecules and micro-organisms directly, in most practical scenarios this interaction is mediated by fluids and extracellular matrices.…”