摘要

       应用了一种利用抗生素抗性基因 (ARG) 分子特征的新方法来跟踪科罗拉多州 Cache la Poudre (Poudre) 和南普拉特河沿岸站点的 ARG 来源。采用了两条证据线：(1) 2 种磺胺和 11 种四环素 ARG 的检测频率和 (2) tet(W) 系统发育和系统发育分析。还构建了一个 GIS 数据库，指示流域中污水处理厂 (WWTP) 和动物饲养场 (AFO) 的位置，以评估周围景观与 ARG 分子特征识别的推定来源的一致性。对先前确定与污水处理厂或 AFO 相关的 tetARG 组的检测频率进行了判别分析。根据对 ARG 检测频率的判别分析，除了一个（South Platte River-3，就在与 Poudre 河汇合处的下游）之外的所有站点都被归类为主要受 WWTP 影响。 tet(W) 系统发育分析也将 South Platte River-3 与推定的 AFO 来源对齐，而系统发育分析表明它与所研究的 AFO 或 WWTP 没有显着差异。南普拉特河-3 位于农业密集区，但南普拉特河的上游部分接收来自丹佛大都市的大量负载。相比之下，位于污水处理厂下游 4 公里处的 Poudre River-4 站点的 tet(W) 系统发育和系统发育也被表征并发现与 AFO 泻湖有显着不同（p < 0.05），正如预期的那样。总的来说，在受影响河流站点的分类和周围景观之间发现了很好的对应关系。虽然整体方法可以扩展到其他流域，但一般研究结果表明，相对于抗生素和其他污染物在天然细菌中选择 ARG，来自特定来源的 ARG 的运输可能是该河流环境中 ARG 增殖的主要机制。

       A novel approach utilizing antibiotic-resistance-gene (ARG) molecular signatures was applied to track the sources of ARGs at sites along the Cache la Poudre (Poudre) and South Platte Rivers in Colorado. Two lines of evidence were employed: (1) detection frequencies of 2 sulfonamide and 11 tetracycline ARGs and (2) tet(W) phylotype and phylogenetic analysis. A GIS database indicating the locations of wastewater treatment plants (WWTPs) and animal feeding operations (AFOs) in the watershed was also constructed to assess congruence of the surrounding landscape with the putative sources identified by ARG molecular signatures. Discriminant analysis was performed on detection frequencies of tetARG groups that were previously identified to be associated with either WWTPs or AFOs. All but one (South Platte River-3, just downstream from the confluence with the Poudre River) of the eight sites were classified as primarily WWTP-influenced based on discriminant analysis of ARG detection frequencies. tet(W) phylotype analysis also aligned South Platte River-3 with putative AFO sources, while phylogenetic analysis indicated that it was not significantly different from the AFOs or WWTPs investigated. South Platte River-3 is situated in an intense agricultural area, but the upstream portion of the South Platte River receives substantial loading from metropolitan Denver. By contrast, tet(W) phylotype and phylogenetics of site Poudre River-4, located 4 km downstream of a WWTP, was also characterized and found to be significantly different from the AFO lagoons (p < 0.05), as expected. In general, a good correspondence was found between classification of the impacted river sites and the surrounding landscape. While the overall approach could be extended to other watersheds, the general findings indicate that transport of ARGs from specific sources is likely the dominant mechanism for ARG proliferation in this riverine environment relative to selection of ARGs among native bacteria by antibiotics and other pollutants.

https://pubs.acs.org/doi/abs/10.1021/es101657s