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Cellular basis in the inhibitory activity of non-thermal plasma against biofilm-forming pathogenic bacteria
- Author(s)
- 서혜미
- Advisor
- 문은표
- Department
- 일반대학원 생명과학과
- Publisher
- The Graduate School, Ajou University
- Publication Year
- 2018-08
- Language
- eng
- Alternative Abstract
- Inactivation of bacterial growth is essential for a healthy human life, and some of the most important advances in agriculture, medicine, and food science have been created by the application of biochemical, cellular, and molecular knowledge of bacterial control. However, inactivation of biofilms formed by various pathogenic bacteria, including Staphylococcus, Pseudomonas, and Pectobacterium bacterial genus, remains to be one of the most unmanageable tasks in the control of bacterial diseases. In this context, the effective inhibition of a biofilm-forming pathogenic bacteria using non-thermal atmospheric plasma has recently emerged as an attractive antimicrobial technique. To study the antimicrobial nature of plasma, various non-thermal atmospheric-pressure plasmas were generated using types of plasma devices and a number of gas sources such as Air, N2, and Helium. Plasma generated by our micro-jet devices using N2 gas effectively inhibited planktonic bacteria, and the applications of PBS pretreated with plasma (PBS/N2Plasma) were found to be more convenient and efficient as compared to direct applications of the plasma. Scavenger assays using various antioxidants revealed that ROS were involved in the inhibitory cellular actions of PBS/N2Plasma, with H2O2 and singlet oxygen being the major active components essential for bacterial death. The subsequent intensive analysis of PBS/N2Plasma, stored at different temperatures and periods, showed that the bactericidal efficacy was well maintained at -80℃ for three months, or at -4℃ for three weeks. The underwater plasma device from a bubbler with 30-50% porosity was shown to effectively inhibit growth of pathogenic bacteria such as Staphylococcus and Pseudomonas. Reactive oxygen species (ROS) are biological molecules that play an important role in bacterial death. The highest number of ROS was detected in the underwater plasma of the bubbler with the porosity of 50%. ROS signaling molecules—in particular, singlet oxygen and H2O2—could play a role in plasma-mediated damage to bacteria. The underwater plasma solution of the bubbler with the porosity of 50% was found to have a strong antimicrobial effect with a considerably low cytotoxic effect on cells, implying that the higher bubbler porosity is more promising in terms of its practical use in plasma medicine. Further studies demonstrated that PBS/N2Plasma effectively inhibited not only the growth of planktonic bacteria, but also the biofilm they formed. The remarkable inhibition on the biofilm was visualized and analyzed using the LIVE/DEAD viability assay and confocal laser scanning microscopy (CLSM) imaging. The 3D CLSM imaging data revealed that the antimicrobial activity of PBS/N2Plasma was sufficiently permeable to affect the cells embedded inside the biofilm. The prominent permeability could be the crucial feature of PBS/N2Plasma that contributes to the effectiveness of biofilm inactivation. Disease control by non-thermal plasma was evaluated using a semi-in vivo assay system with the GFP-tagged crop pathogen, and the efficacy was confirmed by the results showing a significant reduction in disease symptoms.
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- Appears in Collections:
- Graduate School of Ajou University > Department of Bioscience > 3. Theses(Master)
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