摘要

       处理过的废水越来越多地被再利用，以实现干旱地区的可持续水资源管理。本研究的目的是量化循环水中抗生素抗性基因 (ARG) 的分布，特别是在循环水通过分配系统后，并考虑使用点对土壤灌溉的影响。检查了美国西部的三个独立的再生废水分配系统。定量聚合酶链反应 (qPCR) 用于量化与对磺胺类药物 (sul1、sul2)、大环内酯类 (ermF)、四环素 [tet(A)、tet(O)]、糖肽 (vanA) 和甲氧西林 (mecA) 耐药性相对应的 ARG )，此外还有存在于水源性病原体嗜肺军团菌 (Lmip)、大肠杆菌 (gadAB) 和铜绿假单胞菌 (ecfx, gyrB) 中的基因。在一项平行的实验室研究中，在分批微观世界中检查了用二次、氯化或脱氯废水流出物灌溉农业土壤的效果。再生水通过分配系统后检测到更广泛的 ARG，这突出了考虑细菌再生长和使用点 (POU) 整体水质的重要性。使用 qPCR 筛选病原体表明存在 Lmip 和 gadAB 基因，但不存在 ecfx 或 gyrB。在实验室研究中，观察到氯化减少了废水中的 16S rRNA 和 sul2 基因拷贝，而脱氯没有明显影响。在用任何流出物进行单次灌溉事件后培养的土壤浆液中，ARGs 水平不随时间变化。然而，当用二次废水流出物（未氯化或脱氯）反复灌溉时，观察到 sul1 和 sul2 水平升高。这项研究表明，再生水可能是 ARG 的重要水库，尤其是在 POU，并且应将注意力集中在灌溉水中 ARG 的归宿及其对人类健康的影响上。

       Treated wastewater is increasingly being reused to achieve sustainable water management in arid regions. The objective of this study was to quantify the distribution of antibiotic resistance genes (ARGs) in recycled water, particularly after it has passed through the distribution system, and to consider point-of-use implications for soil irrigation. Three separate reclaimed wastewater distribution systems in the western U.S. were examined. Quantitative polymerase chain reaction (qPCR) was used to quantify ARGs corresponding to resistance to sulfonamides (sul1, sul2), macrolides (ermF), tetracycline [tet(A), tet(O)], glycopeptides (vanA), and methicillin (mecA), in addition to genes present in waterborne pathogens Legionella pneumophila (Lmip), Escherichia coli (gadAB), and Pseudomonas aeruginosa (ecfx, gyrB). In a parallel lab study, the effect of irrigating an agricultural soil with secondary, chlorinated, or dechlorinated wastewater effluent was examined in batch microcosms. A broader range of ARGs were detected after the reclaimed water passed through the distribution systems, highlighting the importance of considering bacterial re-growth and the overall water quality at the point of use (POU). Screening for pathogens with qPCR indicated presence of Lmip and gadAB genes, but not ecfx or gyrB. In the lab study, chlorination was observed to reduce 16S rRNA and sul2 gene copies in the wastewater effluent, while dechlorination had no apparent effect. ARGs levels did not change with time in soil slurries incubated after a single irrigation event with any of the effluents. However, when irrigated repeatedly with secondary wastewater effluent (not chlorinated or dechlorinated), elevated levels of sul1 and sul2 were observed. This study suggests that reclaimed water may be an important reservoir of ARGs, especially at the POU, and that attention should be directed toward the fate of ARGs in irrigation water and the implications for human health.

https://www.frontiersin.org/articles/10.3389/fmicb.2013.00130/full