Li Wen, Zhang Wei-Guo, Zhang Ming-Sha, Lei Zhong-Fang, Li Peng-Fu, Ma Yan, Gao Yan
Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology, Nanjing 210014, China; School of Life Sciences, Nanjing University, Nanjing 210093, China.
Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology, Nanjing 210014, China; Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8577, Japan; China Ministry of Agriculture Key Laboratory at Yangtze River Plain for Agricultural Environment, Nanjing 210014, China.
Sci Total Environ. 2022 Dec 15;852:158272. doi: 10.1016/j.scitotenv.2022.158272. Epub 2022 Aug 24.
Abundant antibiotic resistance genes (ARGs) are typically found in mercury (Hg)-contaminated aquatic environments. This phenomenon is partly attributed to the co-resistance, cross-resistance, and shared regulatory responses to Hg and antibiotics. However, it remains unclear whether and how Hg influences the conjugative transfer of ARGs mediated by mobilizable plasmids. In the present study, we found that Hg at the environmentally relevant concentrations (0.001-0.5 mg L) facilitated the conjugative transfer of ARGs through the mobilizable plasmid RP4 from the donor Escherichia coli HB101 to the recipient E. coli K12. Exposure to Hg significantly increases the formation of reactive oxygen species, malondialdehyde production, antioxidant enzyme activities, and cell membrane permeability, while decreasing the concentration of glutathione. Scanning electron microscopy and transmission electron microscopy showed that the cell membrane suffered from oxidative damage, which is beneficial for conjugative transfer. The expression of global regulatory genes (korA, korB, and trbA) negatively regulating conjugative transfer was restrained by Hg, while promoting the expression of positive regulatory genes involved in the mating pair formation system (trbBp and traF) and the DNA transfer and replication systems (trfAp and traJ). Although a high Hg concentration (1.0 mg L) suppressed ARGs conjugative transfer, our results suggest that Hg facilitates the dissemination of ARGs in aquatic environments at environmentally relevant concentrations. This study improves our understanding of ARGs dissemination in Hg-contaminated aquatic environments.
在汞（Hg）污染的水生环境中通常能发现大量抗生素抗性基因（ARGs）。这种现象部分归因于对汞和抗生素的共抗性、交叉抗性以及共同的调控反应。然而，汞是否以及如何影响可移动质粒介导的ARGs接合转移仍不清楚。在本研究中，我们发现环境相关浓度（0.001 - 0.5 mg/L）的汞通过可移动质粒RP4促进了ARGs从供体大肠杆菌HB101向受体大肠杆菌K12的接合转移。暴露于汞会显著增加活性氧的形成、丙二醛的产生、抗氧化酶活性和细胞膜通透性，同时降低谷胱甘肽的浓度。扫描电子显微镜和透射电子显微镜显示细胞膜遭受氧化损伤，这有利于接合转移。负向调节接合转移的全局调控基因（korA、korB和trbA）的表达受到汞的抑制，而参与配对形成系统（trbBp和traF）以及DNA转移和复制系统（trfAp和traJ）的正向调控基因的表达则被促进。尽管高浓度汞（1.0 mg/L）抑制了ARGs的接合转移，但我们的结果表明，在环境相关浓度下，汞促进了ARGs在水生环境中的传播。这项研究增进了我们对ARGs在汞污染水生环境中传播的理解。
