School of Environment, Henan Normal University, Xinxiang 453007, China; School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450046, Henan, China.
College of Life Sciences, Henan Normal University, Xinxiang 453007, China; Henan International Joint Laboratory of Agricultural Microbial Ecology and Technology (Henan Provincial Department of Science and Technology), Henan Normal University, Xinxiang 453007, China.
Sci Total Environ. 2021 Mar 20;761:144303. doi: 10.1016/j.scitotenv.2020.144303. Epub 2020 Dec 14.
Excessive production and utilization of nanoparticles (NPs) at industrial and household levels releases substantial quantities of NPs into the environment. These can be harmful to different types of organisms and cause adverse effects on ecosystems. Purchased TiO and ZnO NPs were characterized via XRD, XPS, FESEM, and Zeta potential. This study elucidates how multidrug resistant Escherichia coli LM13, which was recovered from livestock manure, counteracts the antibacterial activities of TiO and ZnO NPs to survive in the environment. E. coli ATCC25922, which is susceptible to antibiotics, was used as control. A dose-response experiment showed that the antibacterial activity of TiO was lower than that of ZnO NPs and, LM13 was more resistant to NPs than ATCC25922. An AcrAB-TolC efflux pump along with its regulation genes helped LM13 to minimize NP toxicity. Flow cytometry findings also indicated that the intensity of the side-scatter light parameter increased with TiO and ZnO NPs in a dose dependent manner, suggesting NP uptake by the both strains. The generation of reactive oxygen species in LM13 was several-fold lower than in ATCC25922, suggesting that reactive oxygen species mainly contribute to the toxicity mechanism. These results illustrate the necessity to evaluate the impacts of NPs on the survival capacity of bacteria and on the resistance genes in bacteria with higher NP resistance than NP susceptible bacteria.
过量生产和使用纳米粒子（NPs）在工业和家庭水平上会将大量的 NPs 释放到环境中。这些 NPs 可能对不同类型的生物有害，并对生态系统造成不良影响。购买的 TiO 和 ZnO NPs 通过 XRD、XPS、FESEM 和 Zeta 电位进行了表征。本研究阐明了如何从牲畜粪便中回收的多药耐药大肠杆菌 LM13 对抗 TiO 和 ZnO NPs 的抗菌活性以在环境中存活。将对抗生素敏感的大肠杆菌 ATCC25922 用作对照。剂量反应实验表明，TiO 的抗菌活性低于 ZnO NPs，并且 LM13 比 ATCC25922 更能抵抗 NPs。AcrAB-TolC 外排泵及其调节基因帮助 LM13 最大程度地减少 NP 毒性。流式细胞术的研究结果也表明，随着 TiO 和 ZnO NPs 的剂量依赖性增加，侧散射光参数的强度增加，这表明两种菌株都摄取了 NP。在 LM13 中产生的活性氧物种的数量比 ATCC25922 低几倍，这表明活性氧物种主要有助于毒性机制。这些结果表明，有必要评估 NPs 对具有比 NP 敏感细菌更高 NP 抗性的细菌的生存能力和抗性基因的影响。
