Cold Plasma Inactivation of Bacterial Biofilms and Reduction of Quorum Sensing Regulated Virulence Factors.
Cold Plasma Inactivation of Bacterial Biofilms and Reduction of Quorum Sensing Regulated Virulence Factors.
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DOI：
10.1371/journal.pone.0138209
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Bourke P
中科院分区：
文献类型：
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作者：
Ziuzina D;Boehm D;Patil S;Cullen PJ;Bourke P
这项工作的主要目的是研究大气冷等离子体 (ACP) 对一系列通常与食源性和医疗保健相关的人类感染有关的微生物生物膜的影响，以及对铜绿假单胞菌群体感应 (QS) 调节的毒力因子（如绿脓素、弹性蛋白酶 (Las B) 和 ACP 治疗后生物膜形成能力）的影响。还检查了处理因素（即处理时间和血浆暴露模式）对 ACP 抗菌活性的影响。分别使用菌落计数和 XTT 测定，从可培养性降低和代谢活性保留方面评估了大肠杆菌、单核细胞增生李斯特菌和金黄色葡萄球菌的抗生物膜活性。所有样品均使用密封聚丙烯容器进行“包装”处理，并在 80 kV 下产生 0、60、120 和 300 秒的高压介质阻挡放电 ACP，处理后存储时间为 24 小时。根据菌落计数，ACP 处理 60 秒可将大肠杆菌种群减少至不可检测的水平，而需要 300 秒才能显着减少单核细胞增生李斯特菌和金黄色葡萄球菌生物膜的种群。 XTT 测定获得的结果表明可能诱导存活但不可培养的细菌状态。对于铜绿假单胞菌QS相关毒力因子，短处理时间后绿脓素的产生被显着抑制，但弹性蛋白酶的减少仅在300秒后才显着减少，并且ACP处理后并未实现实际生物膜形成的减少。重要的是，无论治疗模式和持续时间如何，毒力因子的减少与细菌上清液对 CHO-K1 细胞的细胞毒性作用的减少相关。这项研究的结果表明，ACP 技术是灭活已建立的生物膜的有效策略，并且可能在减弱病原菌毒力方面发挥重要作用。有必要进行进一步的研究，以提出抑制 QS 的直接证据以及可能发生这种情况的机制。
The main objectives of this work were to investigate the effect of atmospheric cold plasma (ACP) against a range of microbial biofilms commonly implicated in foodborne and healthcare associated human infections and against P. aeruginosa quorum sensing (QS)-regulated virulence factors, such as pyocyanin, elastase (Las B) and biofilm formation capacity post-ACP treatment. The effect of processing factors, namely treatment time and mode of plasma exposure on antimicrobial activity of ACP were also examined. Antibiofilm activity was assessed for E. coli, L. monocytogenes and S. aureus in terms of reduction of culturability and retention of metabolic activity using colony count and XTT assays, respectively. All samples were treated ‘inpack’ using sealed polypropylene containers with a high voltage dielectric barrier discharge ACP generated at 80 kV for 0, 60, 120 and 300 s and a post treatment storage time of 24 h. According to colony counts, ACP treatment for 60 s reduced populations of E. coli to undetectable levels, whereas 300 s was necessary to significantly reduce populations of L. monocytogenes and S. aureus biofilms. The results obtained from XTT assay indicated possible induction of viable but non culturable state of bacteria. With respect to P. aeruginosa QS-related virulence factors, the production of pyocyanin was significantly inhibited after short treatment times, but reduction of elastase was notable only after 300 s and no reduction in actual biofilm formation was achieved post-ACP treatment. Importantly, reduction of virulence factors was associated with reduction of the cytotoxic effects of the bacterial supernatant on CHO-K1 cells, regardless of mode and duration of treatment. The results of this study point to ACP technology as an effective strategy for inactivation of established biofilms and may play an important role in attenuation of virulence of pathogenic bacteria. Further investigation is warranted to propose direct evidence for the inhibition of QS and mechanisms by which this may occur.