摘要

       抗生素耐药性的出现和蔓延对人类健康和环境生态系统构成了巨大威胁。然而，关于细胞外 DNA (eDNA) 中的 ARG 库知之甚少。在本研究中，医院、制药工业、废水处理厂 (WWTP) 和污泥中的 10 个 ARG（sul1、sul2、tetW、tetX、ermA、ermB、blaTEM、ampC、cat 和 cmr）和 I 类整合子 (intI1) 和通过定量聚合酶链反应 (qPCR) 评估了以 eDNA 和细胞内 DNA (iDNA) 形式存在的猪粪和城市湖泊中的沉积物。结果表明，每克污泥干重含有 7.31×103 至 1.16×1010 个拷贝的细胞外 ARGs（eARGs）和 1.04×105 至 2.74×1012 个拷贝的细胞内 ARGs（iARGs）。 eARGs占总ARGs比例最高的医院污泥（11.02-89.63%），其次是城市湖泊沉积物，表明这些地区的大部分ARGs是由eARGs贡献的。污水处理厂和制药工业污泥中eARGs的相对丰度高于iARGs，此外，1/3和5/9检测到的eARGs分别高于医院污泥和城市湖泊底泥中提取的iDNA中的ARGs。此外，eARG 的转化能力表明吸附的 eARG 比游离的 eARG 更优先与感受态细胞偶联。这些发现强调需要关注 eARGs 对抗生素耐药性向环境传播的贡献，以及未来在减轻 eARGs 在环境中传播的需求。

       The emergence and spread of antibiotic resistance has pose a huge threat to both human health and environmental ecosystem. However, little is known regarding the pool of ARGs in extracellular DNA (eDNA). In this study ten ARGs (sul1, sul2, tetW, tetX, ermA, ermB, blaTEM, ampC, cat and cmr) and class I integron (intI1) in the sludge from hospital, pharmaceutical industry, wastewater treatment plant (WWTP), and swine manure, and sediment in urban lake in the form of both eDNA and intracellular DNA (iDNA) were evaluated by quantitative polymerase chain reaction (qPCR). The results showed that every gram of sludge dry weight contained from 7.31 × 103 to 1.16 × 1010 copies of extracellular ARGs (eARGs) and from 1.04 × 105 to 2.74 × 1012 copies of intracellular ARGs (iARGs). The sludge from hospital with the highest ratio of eARGs to total ARGs (11.02–89.63%), followed by the sediment from urban lake, implying that most of the ARGs in these regions were contributed by eARGs. The relative abundance of eARGs were higher than iARGs in sludge from WWTP and pharmaceutical industry, moreover, 1/3 and 5/9 detected eARGs were higher than the ARGs in the iDNA extracted from sludge of hospital and sediment from urban lake, respectively. Furthermore, the transforming ability of eARGs suggesting that adsorbed eARG is more preferentially coupled to the competent cells than free eARG. These findings highlight the need to focus attention on the contribution of eARGs to the dissemination of antibiotic resistance into environment, and also future needs in mitigating the spread of eARGs in the environment.

https://www.sciencedirect.com/science/article/pii/S0160412018322621