摘要

     在集约化水产养殖环境中，抗药性基因（ARGs）的日益流行和传播，已成为食品安全和公众健康关注的焦点。然而，在工业化循环水产养殖系统（RAS）中，ARGs的水平及其潜在的传播因子尚未得到全面的研究。本研究以中国北方地区的一个RAS（包括水、鱼、粪便、颗粒饲料和生物膜样品）为研究对象，对14种不同的ARG标记物和2种可移动基因元件（MGEs）的水平进行了研究。qnrA、qnrB、qnrS、qepA、aac（6′）-Ib和floR是优势ARGs，平均浓度分别为4.51-7.74拷贝/L和5.36-13.07拷贝/g，表明ARGs在没有抗生素使用史的RAS中普遍存在。与进水相比，即使在最后的紫外线处理后，RAS水中的ARGs水平也显著升高。在RAS中，蛋白菌、疣状芽胞菌、拟杆菌和平纹丝菌是优势菌。值得注意的是，伴随着发现大量的ARGs，观察到潜在机会性病原体的水平升高，表明人类病原体捕获ARGs和MGEs的风险在增加。本研究首次揭示了养殖鱼类及其粪便、颗粒饲料作为引入来源和处理方法的选择作用共同驱动了ARGs的传播。水环境因子的选择及其影响所形成的细菌群落迁移是ARGs在RAS中传播的决定性因素。

     The increasing prevalence and spread of antibiotic resistance genes (ARGs) in intensive aquaculture environments are of great concern to food safety and public health. However, the level of ARGs and their potential propagation factors in an industrial recirculating aquaculture system (RAS) have not previously been comprehensive explored. In this study, the levels of 14 different ARG markers and 2 kinds of mobile genetic elements (MGEs) were investigated in a RAS (including water, fish, feces, pellet feed meal, and biofilm samples) located northern China. qnrA, qnrB, qnrS, qepA, aac(6′)-Ib, and floR were dominant ARGs, which average concentration levels were presented at 4.51–7.74 copies/L and 5.36–13.07 copies/g, respectively, suggesting that ARGs were prevalent in RAS with no recorded history of antibiotic use. Elevated level of ARGs was found in water of RAS even after the final UV treatment compared with its influent. In RAS, Proteobacteria, Verrucomicrobia, Bacteroidetes, and Planctomycetes were the predominant phyla. Notably, elevated levels of potential opportunistic pathogens were observed along with abundant ARGs suggesting an increasing risk of capturing ARGs and MGEs for human pathogens. This study has revealed for the first time that reared fish, their feces, pellet feed meal as the introduction sources and the selection roles of treatment units co-driven the ARG profile, and the co-selection of water environmental factors and their consequently induced bacterial community shifts formed by their influence are the determining drivers for the ARG propagation in RAS.

     https://www.sciencedirect.com/science/article/pii/S0269749119372707