Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing, 100049, China.
Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China.
Environ Pollut. 2021 Jan 1;268(Pt B):115903. doi: 10.1016/j.envpol.2020.115903. Epub 2020 Oct 20.
Co-selection of antibiotic resistance genes (ARGs) by heavy metals might facilitate the spread of ARGs in the environments. Cadmium contamination is ubiquitous, while, it remains unknown the extent to which cadmium (Cd) impact plasmid-mediated transfer of ARGs in aquatic bacterial communities. In the present study, we found that Cd amendment at sub-inhibitory concentration significantly increased conjugation frequency of RP4 plasmid from Pseudomonas putida KT2442 to a fresh water microbial community by liquid mating method. Cd treatment (1-100 mg/L) significantly increased the cell membrane permeability and antioxidant activities of conjugation mixtures. Amendments of 10 and 100 mg/L Cd significantly enhanced the mRNA expression levels of mating pair formation gene (trbBp) and the DNA transfer and replication gene (trfAp) due to the repression of regulatory genes (korA, korB and trbA). Phylogenetic analysis of transconjugants indicated that Proteobacteria was the dominant recipients and high concentration of Cd treatment resulted in expanded recipient taxa. This study suggested that sub-inhibitory Cd contamination would facilitate plasmid conjugation and contributed to the maintenance and spread of plasmid associated ARGs, and highlighted the urgent need for effective remediation of Cd in aquatic environments.
重金属的协同选择可能会促进抗生素抗性基因（ARGs）在环境中的传播。镉污染普遍存在，但目前尚不清楚镉（Cd）对水细菌群落中质粒介导的 ARGs 转移的影响程度。在本研究中，我们发现亚抑制浓度的 Cd 修正案通过液体交配方法显着增加了铜绿假单胞菌 KT2442 的 RP4 质粒向淡水微生物群落的接合频率。Cd 处理（1-100mg/L）显着增加了接合混合物的细胞膜通透性和抗氧化活性。由于调节基因（korA、korB 和 trbA）的抑制，10 和 100mg/L Cd 的修正案显着提高了交配对形成基因（trbBp）和 DNA 转移和复制基因（trfAp）的 mRNA 表达水平。转导子的系统发育分析表明，变形菌门是主要的受体，高浓度的 Cd 处理导致受体分类群扩大。本研究表明，亚抑制浓度的 Cd 污染会促进质粒的接合，并有助于质粒相关 ARGs 的维持和传播，突出了迫切需要对水生环境中的 Cd 进行有效修复。
