摘要

美国中西部地区以猪的高浓度农业生产为主，导致猪粪施用于人工地下排水的土地上。先前的报道已经指出在施用抗微生物剂的受限动物饲喂操作周围地表水和地下水中的抗生素抗性基因（ARG）水平升高。虽然以前的研究已经检查了封闭猪饲喂操作周围的ARG的发生，但很少有信息知道它们如何从接受猪肥料应用的瓦片排出的田地运输影响下游环境。为了进一步了解这一领域的知识，在农业上主导的South Fork Iowa河流域的五个地点采集了水样，其中76,000公顷的流域有约84万头猪。每月从三个流场和两个主要人工地下排水口收集样本。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基因的丰度从低于定量限度到> 107拷贝100 mL-1水。 89％的水样含有这两种ARG中的一种。结果显示，当通过16S rRNA丰度归一化时，主要排水渠道中的ermB和ermF明显多于溪流样本（p <0.0001）。当归一化到16S rRNA丰度时，两个人造排水位置均显示ermB和ermF丰度的时间趋势。在春季和秋末发生的人造排水样本中发现的较高的抗性基因浓度可能是由于施用粪肥造成的。

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 genesermB, 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