Biofilm formation by Pseudomonas aeruginosa (P. aeruginosa) is known to be characteristic of this organism. This bacterium is considered one of the most life-threatening bacteria and has been identified as a priority pathogen for research by WHO. Biofilm-producing P. aeruginosa is a concern in many parts of the world due to antibiotic resistance. Alginate also plays an important role in the biofilm formation of P. aeruginosa as well as the emergence of antibiotic resistance in biofilms. In addition, the systems of toxin-antitoxin( TA) play an important role in biofilm formation. Metal nanoparticle(NP) such as zinc oxide (ZnO) also have extensive biological properties, especially anti-biofilm properties. Therefore, this study was conducted in relation to the importance of zinc oxide nanoparticles (ZnO NPs) in biofilm formation and also the correlation of gene expression of TA systems in clinical isolates of P. aeruginosa. A total of 52 P. aeruginosa isolates were collected from burns (n = 15), UTI (n = 31), and trachea (n = 6) in hospitals in Ilam between May 2020 and October 2020. Biofilm formation was assessed using a microtiter plate assay. MIC and sub-MIC concentrations of ZnO NPs (10–30 nm with purity greater than 99.8%) in P. aeruginosa were determined. Subsequently, biofilm formation was investigated using sub-MIC concentrations of ZnO NPs. Finally, total RNA was extracted and RT- qPCR was used to determine the expression levels of genes of mazEF, mqsRA, and higBA of TA systems. Six isolates of P. aeruginosa were found to form strong biofilms. The results showed that ZnO NPs were able to inhibit biofilm formation. In our experiments, we found that the sub-MIC concentration of ZnO NPs increased the gene expression of antitoxins mazE and mqsA and toxin higB of TA systems treated with ZnO NPs. In the present study, ZnO NPs were shown to effectively inhibit biofilm formation in P. aeruginosa. Our results support the relationship between TA systems and ZnO NPs in biofilm formation in P. aeruginosa. Importantly, the expression of antitoxins mazE and mqsA was high after treatment with ZnO NPs, but not that of antitoxin higA.

中文翻译：

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纳米氧化锌对铜绿假单胞菌生物膜形成及毒素-抗毒素系统基因表达的影响

已知铜绿假单胞菌（P. aeruginosa）形成的生物膜是该生物体的特征。这种细菌被认为是最威胁生命的细菌之一，并已被世界卫生组织确定为研究的优先病原体。由于抗生素耐药性，产生生物膜的铜绿假单胞菌在世界许多地区都受到关注。海藻酸盐还在铜绿假单胞菌生物膜形成以及生物膜中抗生素耐药性的出现中发挥着重要作用。此外，毒素-抗毒素（TA）系统在生物膜形成中发挥着重要作用。氧化锌（ZnO）等金属纳米粒子（NP）也具有广泛的生物学特性，尤其是抗生物膜特性。因此，本研究是针对氧化锌纳米颗粒 (ZnO NP) 在生物膜形成中的重要性以及铜绿假单胞菌临床分离株中 TA 系统基因表达的相关性进行的。2020 年 5 月至 2020 年 10 月期间，从伊拉姆医院的烧伤 (n = 15)、尿路感染 (n = 31) 和气管 (n = 6) 中收集了总共 52 株铜绿假单胞菌。使用微量滴定仪评估生物膜形成平板测定。测定了铜绿假单胞菌中 ZnO NP（10-30 nm，纯度大于 99.8%）的 MIC 和亚 MIC 浓度。随后，使用亚 MIC 浓度的 ZnO NPs 研究生物膜的形成。最后提取总RNA，采用RT-qPCR测定TA系统中mazEF、mqsRA、higBA基因的表达水平。发现六种铜绿假单胞菌分离株形成牢固的生物膜。结果表明，ZnO NPs 能够抑制生物膜的形成。在我们的实验中，我们发现亚 MIC 浓度的 ZnO NP 增加了用 ZnO NP 处理的 TA 系统的抗毒素 mazE 和 mqsA 以及毒素 higB 的基因表达。在本研究中，ZnO NPs 被证明可以有效抑制铜绿假单胞菌生物膜的形成。我们的结果支持 TA 系统和 ZnO NPs 在铜绿假单胞菌生物膜形成中的关系。重要的是，用 ZnO NP 处理后，抗毒素 mazE 和 mqsA 的表达较高，但抗毒素 higA 的表达不高。