摘要

    在集约化水产养殖环境中，抗生素抗性基因（ARGs）的流行和传播日益增加，这与食品安全和公共卫生息息相关。但是，以前尚未全面研究工业循环水产养殖系统（RAS）中ARG的水平及其潜在的传播因子。在这项研究中，我们对位于中国北方的RAS（包括水，鱼，粪便，颗粒饲料和生物被膜样品）中的14种不同的ARG标记和2种移动遗传元素（MGEs）的水平进行了调查。 qnrA，qnrB，qnrS，qepA，aac（6'-Ib）和floR是主要的ARG，平均浓度水平分别为4.51-7.74拷贝/ L和5.36-13.07拷贝/ g，表明ARG是普遍的在未记录抗生素使用史的RAS中使用。与进水相比，即使在经过最终的紫外线处理后，RAS水中的ARGs含量也升高。在RAS中，主要细菌是变形杆菌，疣状微生物菌，拟杆菌和扁平菌。值得注意的是，观察到潜在机会病原体水平升高，同时富含大量的ARG，表明捕获人类病原体的ARG和MGE的风险增加。这项研究首次揭示了养鱼，它们的粪便，颗粒饲料作为引入源以及处理单位的选择作用共同驱动了ARG谱，共同选择了水环境因素及其诱生细菌。由它们的影响形成的群落转移是RAS中ARG传播的决定性驱动因素。

    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/abs/pii/S0269749119372707