摘要

土壤中的抗生素抗性基因对人类健康构成潜在风险。他们可以通过用未经处理或未经处理的废水进行灌溉来进入土壤。我们假设水流路径引发抗生素抗性的形成，因为它们通过土壤运输抗生素，多抗性细菌和游离抗性基因。为了测试这一点，我们仅用废水灌溉土壤核心一次或两次，或者用添加了磺胺甲恶唑（SMX）和环丙沙星（CIP）的废水灌溉土壤核心。处理还包含染料以染色水流路径，并允许从未污染的块状土壤分别取样。 SMX和CIP的命运通过吸附实验，渗滤液分析和土壤中总的和可提取的SMX和CIP的定量评估。通过qPCR对SMX（sul1和sul2）和CIP（qnrB和qnrS）的抗性基因的丰度进行量化。 CIP的吸附比染料和SMX大。环丙沙星仅积聚在水流路径中，但抗性基因qnrB和qnrS未检测到。水流路径中的SMX浓度与散装土壤的浓度相比增加了一倍，苏氨酸基因的丰度也是如此，特别是sul1基因。这些结果表明，流动路径确实起到抗生素积累的热点作用，并引发土壤中抗性基因的形成。它们的传播还取决于抗生素的移动性，SMX比CIP大得多。

Antibiotic resistance genes in soil pose a potential risk for human health. They can enter the soil by irrigation with untreated or insufficiently treated waste water. We hypothesized that water flow paths trigger the formation of antibiotic resistance, since they transport antibiotics, multi-resistant bacteria and free resistance genes through the soil. To test this, we irrigated soil cores once or twice with waste water only, or with waste water added with sulfamethoxazole (SMX) and ciprofloxacin (CIP). The treatments also contained a dye to stain the water flow paths and allowed to sample these separately from unstained bulk soil. The fate of SMX and CIP was assessed by sorptionexperiments, leachate analyses and the quantification of total and extractable SMX and CIP in soil. The abundance of resistance genes to SMX (sul1 and sul2) and to CIP (qnrBand qnrS) was quantified by qPCR. The sorption of CIP was larger than the dye and SMX. Ciprofloxacin accumulated exclusively in the water flow paths but the resistance genes qnrB and qnrS were not detectable. The SMX concentration in the water flow paths doubled the concentration of the bulk soil, as did the abundance of sul genes, particularly sul1 gene. These results suggest that flow paths do function as hotspots for the accumulation of antibiotics and trigger the formation of resistance genes in soil. Their dissemination also depends on the mobility of the antibiotic, which was much larger for SMX than for CIP.

https://www.sciencedirect.com/science/article/pii/S0045653517319203