摘要

       2013 年 9 月创纪录的洪水对科罗拉多前沿山脉的房屋和基础设施造成了巨大破坏，并严重影响了 Cache La Poudre 河流域。鉴于该流域作为跟踪抗生素抗性基因 (ARG) 传播环境途径的试验台的独特性质，我们试图确定极端洪水对河水和沉积物中 ARG 水库的影响。我们利用高通量 DNA 测序获得洪水前后 ARG 的宏基因组图谱，并研究了 23 种抗生素和 14 种金属作为洪水后恢复期间的推定选择剂。在样本中确定了 277 个 ARG 亚型，洪水后总体积水 ARG 下降，但在洪水后 10 个月，在原始地点和历史上受污水处理厂和动物饲养作业严重影响的地点恢复到接近洪水前的丰度.对 52,556 个支架的从头组装测序读数的网络分析确定了可能位于移动遗传元件上的 ARG，每个质粒相关支架有多达 11 个 ARG。散装水细菌系统发育与 ARG 剖面相关，而沉积物系统发育沿河流的人为梯度变化。这次罕见的洪水为深入了解影响 ARG 在流域中传播的因素提供了机会。

       Record-breaking floods in September 2013 caused massive damage to homes and infrastructure across the Colorado Front Range and heavily impacted the Cache La Poudre River watershed. Given the unique nature of this watershed as a test-bed for tracking environmental pathways of antibiotic resistance gene (ARG) dissemination, we sought to determine the impact of extreme flooding on ARG reservoirs in river water and sediment. We utilized high-throughput DNA sequencing to obtain metagenomic profiles of ARGs before and after flooding, and investigated 23 antibiotics and 14 metals as putative selective agents during post-flood recovery. With 277 ARG subtypes identified across samples, total bulk water ARGs decreased following the flood but recovered to near pre-flood abundances by ten months post-flood at both a pristine site and at a site historically heavily influenced by wastewater treatment plants and animal feeding operations. Network analysis of de novo assembled sequencing reads into 52,556 scaffolds identified ARGs likely located on mobile genetic elements, with up to 11 ARGs per plasmid-associated scaffold. Bulk water bacterial phylogeny correlated with ARG profiles while sediment phylogeny varied along the river’s anthropogenic gradient. This rare flood afforded the opportunity to gain deeper insight into factors influencing the spread of ARGs in watersheds.

https://www.nature.com/articles/srep38432