摘要

       在加拿大北极地区，将城市污水排入苔原湿地是一种常见的做法。城市污水中存在着抗药性细菌及其所含的抗药性基因（ARGs），对北极地区污水中的ARGs缺乏认识。本研究旨在探讨北极苔原湿地生态系统中ARGs受人为污水源的影响。2016年夏季，在加拿大努纳武特的Sanikiluaq和Naujaat的因纽特人社区研究了两个湿地。从湿地土壤和水体中提取基因组DNA，用定量聚合酶链反应（qPCR）分析了9种临床相关ARGs（sul1、sul2、mecA、vanA、qnrS、ermB、tetO、blaTEM、blaCTX-M）和1个整合子基因（int1）。水文和水质测量与微生物采样一起进行。基因靶点始终存在于废水中，并且在整个湿地都存在，除了vanA和mecA。由于水力停留时间短（<2 天），在春季新鲜期间ARGs的浓度更高，这与处理性能下降一致。未受影响湿地的环境抗逆性高于Naujaat水体中int1、sul1、sul2、blaCTX-M和Sanikiluaq土壤中sul1、qnrS和tetO的检测限浓度。一级速率常数是广泛变化的，并且对基因靶点有特异性。受城市污水影响，冻土带湿地中ARGs浓度高于基准点，水文条件对其空间分布和水平有很大影响。

       In the Canadian Arctic, it is common practice to discharge municipal wastewater into tundra wetlands. Antibiotic resistant bacteria and the antibiotic resistance genes (ARGs) they contain can be present in municipal wastewater and there is a scarcity of knowledge on ARGs in wastewater in Arctic environments. This study was initiated on the fate of ARGs in tundra wetland ecosystems impacted by anthropogenic wastewater sources in Arctic communities. In the summer season of 2016, two wetlands were studied in the Inuit communities of Sanikiluaq and Naujaat in Nunavut, Canada. Genomic DNA was extracted from both soil and water during the spring freshet and late summer in the wetlands, and a suite of nine clinically relevant ARGs (sul1, sul2, mecA, vanA, qnrS, ermB, tetO, bla_TEM, bla_CTX-M), and an integron gene (int1) were analyzed using quantitative polymerase chain reaction (qPCR). Hydrological and water quality measurements were conducted in conjunction with the microbiological sampling. Gene targets were consistently present in the wastewater, and throughout both wetlands, except for vanA and mecA. Concentrations of ARGs were greater during the spring freshet, due to short hydraulic retention times (<2 days), which coincided with decreased treatment performance. The environmental resistome in un-impacted wetlands had above detection limit concentrations of int1, sul1, sul2, bla_CTX-M in water in Naujaat, and sul1, qnrS and tetO in soil in Sanikiluaq. First-order rate constants were widely variable and specific to the gene target. ARGs were present in concentrations elevated above baseline reference sites in tundra wetlands influenced by municipal wastewater, and hydrological conditions had a large impact on their spatial distribution and levels.

       https://www.sciencedirect.com/science/article/pii/S0048969718321545?via%3Dihub