Evaluation of the Direct and Indirect Bactericidal Effect of Low-Temperature Gas-Discharge Plasma on Bacteria In Vitro

Introduction. The application of atmospheric pressure low-temperature gas discharge plasma, frequently referred to as cold atmospheric plasma (CAP), provides a unique tool for dealing with urgent biomedical issues. CAPs contains a large number of radicals and molecules in an excited state, among which reactive oxygen and nitrogen species (RONS) play a major role, and also includes electrons and light radiation. RONS generated by the plasma jet interact with the membrane cell and get into the intracellular space. Their activity can lead to lipid peroxidation, DNA damage, protein denaturation, and cell metabolism disruption, which induces ‘oxidative stress’ in cells.

Materials and methods. This study assessed the local bactericidal activity of CAPs against representative strains of Gram-positive and Gram-negative bacteria. The following bacterial monocultures were used: Gram-negative — Escherichia coli and Pseudomonas fluorescens, Gram-positive — Bacillus megaterium and Mycobacterium sp. Light microscopy and bacterial survival assessment based on changes in the growth suppression area were applied. Spectrophotometry was applied to analyze the plasma ray's radical composition.

Results. Optimal exposure parameters were determined to ensure effective test bacterial culture inactivation. Three and 24 hours after the experiment, the bacterial growth inhibition zone was much larger for Gram-negative bacteria than for Gram-positive bacteria. Meanwhile, the area for Mycobacterium sp. was the least of all. The effect of increasing the growth suppression area after treatment intensified over time for all bacterial types. Plasma treated biomass cultures and bacterial growth activity analysis revealed that BSA became unsuitable for bacterial growth after treatment.

Conclusion. The results confirm the promise of local application of CAPs as a safe and effective physical method of antimicrobial treatment in conjunction with disinfection and epidemiology.

Contribution:
Abrashitov G.N. — collection and processing of material, statistical processing of data, writing of text, editing, responsibility for the integrity of all parts of the article;
Manchenko D.M. — concept and design of the study, responsibility for the integrity of all parts of the article;
Leontyeva M.R. — concept and design of the study, approval of the final version of the article, responsibility for the integrity of all parts of the article;
Yakunin V.G. — concept and design of the study, collection and processing of material;
Timoshenko V.Yu. — concept and design of the study, approval of the final version of the article.

Funding. This study was not supported by any external sources of funding.

Conflict of interest. The authors declare no obvious or potential conflicts of interest in connection with the publication of this article.

Received: 07.07.2025 / Accepted: 20.08.2025 / Published: 10.09.2025

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