Department of Physics, University of Arkansas, Fayetteville, AR 72701, USA.
Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA.
Int J Mol Sci. 2023 Jul 20;24(14):11704. doi: 10.3390/ijms241411704.
Silver (Ag) in different forms has been gaining broad attention due to its antimicrobial activities and the increasing resistance of bacteria to commonly prescribed antibiotics. However, various aspects of the antimicrobial mechanism of Ag have not been understood, including how Ag affects bacterial motility, a factor intimately related to bacterial virulence. Here, we report our study on how Ag ions affect the motility of bacteria using swimming, tethering, and rotation assays. We observed that the bacteria slowed down dramatically by >70% when subjected to Ag ions, providing direct evidence that Ag ions inhibit the motility of bacteria. In addition, through tethering and rotation assays, we monitored the rotation of flagellar motors and observed that the tumbling/pausing frequency of bacteria increased significantly by 77% in the presence of Ag ions. Furthermore, we analyzed the results from the tethering assay using the hidden Markov model (HMM) and found that Ag ions decreased bacterial tumbling/pausing-to-running transition rate significantly by 75%. The results suggest that the rotation of bacterial flagellar motors was stalled by Ag ions. This work provided a new quantitative understanding of the mechanism of Ag-based antimicrobial agents in bacterial motility.
由于其抗菌活性以及细菌对常用处方抗生素的耐药性不断增加，不同形式的银（Ag）受到了广泛关注。然而，Ag 的抗菌机制的各个方面尚未被理解，包括 Ag 如何影响细菌的运动性，这是与细菌毒力密切相关的一个因素。在这里，我们报告了我们使用游泳、系泊和旋转测定法研究 Ag 离子如何影响细菌运动性的研究。我们观察到，当细菌受到 Ag 离子的作用时，其运动速度急剧下降超过 70%，这直接证明了 Ag 离子抑制了细菌的运动性。此外，通过系泊和旋转测定法，我们监测了鞭毛马达的旋转，并观察到在存在 Ag 离子的情况下，细菌的翻滚/暂停频率显著增加了 77%。此外，我们使用隐马尔可夫模型（HMM）分析了系泊测定法的结果，发现 Ag 离子使细菌翻滚/暂停-跑动的转变率显著降低了 75%。结果表明，Ag 离子使细菌的鞭毛马达旋转停滞。这项工作为理解 Ag 基抗菌剂在细菌运动性方面的抗菌机制提供了新的定量认识。
