摘要

在美国中西部，农业生产以高浓度的猪为主，导致猪粪通过人工地下排水施用于土地上。先前的报道表明，在实施抗菌药物的密闭动物饲养作业附近，地表水和地下水中的抗生素抗性基因（ARG）水平升高。尽管先前的研究已经研究了在受限的猪饲喂操作周围发生ARG的情况，但鲜为人知的是它们如何从接受猪粪施用的地砖排水的田间运输到下游环境。为了进一步了解这一领域，我们从农业支配的南爱荷华河流域的五个地点收集了水样，在76,000公顷的流域中存有约84万头猪。每月从三个溪流站点和两个主要的地下人工排水口采集样品。使用qPCR分析样品的大环内酯抗性基因ermB，ermF和16S rRNA基因丰度。 erm基因的丰度范围从低于定量限到> 107拷贝100 mL-1水。 89％的溪流水样品包含这两种ARG中的一种。结果表明，当通过16S rRNA丰度归一化时，主要排水口的ermB和ermF明显比流样品多（p <0.0001）。当标准化为16S rRNA丰度时，两个人工引流位置均显示ermB和ermF丰度的时间趋势。在春季中旬和秋季后期出现的人工排水样品中鉴定出的较高抗性基因浓度可能是由于施肥所致。

The Midwestern United States is dominated by agricultural production with high concentrations of swine, leading to application of swine manure onto lands with artificial subsurface drainage. Previous reports have indicated elevated levels of antibiotic resistance genes (ARGs) in surface water and groundwater around confined animal feeding operations which administer antimicrobials. While previous studies have examined the occurrence of ARGs around confined swine feeding operations, little information is known how their transport from tile-drained fields receiving swine manure application impacts downstream environments. To further our knowledge in this area, water samples were collected from five locations in the agriculturally dominated South Fork Iowa River Watershed with approximately 840,000 swine present in the 76,000 ha basin. Samples were collected monthly from three stream sites and two main artificial subsurface drainage outlets. Samples were analyzed for macrolide resistance genes ermB, ermF and 16S rRNAgene abundance using qPCR. Abundance of erm genes ranged from below limits of quantification to > 107 copies 100 mL− 1 water. Eighty-nine percent of stream water samples contained one of these two ARGs. Results indicate significantly more ermB and ermF in main drainage outlets than stream samples when normalized by 16S rRNA abundance (p < 0.0001). Both artificial drainage locations revealed temporal trends for ermB and ermF abundance when normalized to 16S rRNA abundance. The higher resistance gene concentrations identified in artificial drainage samples occurring mid-Spring and late-Fall are likely due to manure application.

https://www.sciencedirect.com/science/article/pii/S0048969717321137