摘要

流域水库的快速建设产生了一个河流-水库系统，其中包含了全球现代水生环境中从河流系统到水库系统的环境梯度。河流水库系统中抗生素抗性基因（ARG）的概况对于更好地了解其在水生生态环境中的动力学机制至关重要。在这项研究中，我们使用高通量定量PCR研究了代表性河水系统中ARG和移动遗传元素（MGE）的多样性，丰度，分布，并基于结构方程模型（SEM）对影响ARG的因素（例如抗生素，细菌生物量，细菌群落和MGE）进行了排序。 ARGs和MGEs的绝对丰度的季节性变化与局部降雨表现出相似的趋势，这表明降雨引起的季节径流有可能促进ARGs和MGEs的绝对丰度。相比之下，环境梯度在河流水库系统中的ARGs和MGEs的检测数量，相对丰度，分布模式中起着更重要的作用。此外，环境梯度还使河流系统中与ARGs亚型，MGEs和细菌属相关的共生模式与水库系统中的同时发生模式不同。 SEM显示，MGE在塑造ARG轮廓方面贡献最大。总体而言，我们的发现可能通过影响MGE，抗生素，致病菌群落和非致病菌群落，为河流梯度系统中环境梯度对ARGs动力学的机理提供了新颖的见解。

The rapid construction of reservoir in river basin generates a river-reservoir system containing an environmental gradient from river system to reservoir system in modern aquatic environment worldwide. Profiles of antibiotic resistance genes (ARGs) in river-reservoir system is essential to better understand their dynamic mechanisms in aquatic eco-environment. In this study, we investigated the diversity, abundance, distribution of ARGs and mobile genetic elements (MGEs) in a representative river-reservoir system using high-throughput quantitative PCR, as well as ranked the factors (e.g. antibiotics, bacterial biomass, bacteria communities, and MGEs) influencing the patterns of ARGs based on structural equation models (SEMs). Seasonal variations in absolute abundance of ARGs and MGEs exhibited similar trends with local rainfall, suggesting that seasonal runoff induced by the rainfall potentially promote the absolute abundance of ARGs and MGEs. In contrast, environmental gradient played more important roles in the detected number, relative abundance, distribution pattern of ARGs and MGEs in the river-reservoir system. Moreover, environmental gradient also made the co-occurrence patterns associated with ARGs subtypes, MGEs and bacteria genera in river system different from those in reservoir system. The SEMs revealed that MGEs contributed the most to shape the ARG profiles. Overall, our findings provide novel insights into the mechanisms of environmental gradient on ARGs dynamics in river-reservoir system, probably via influencing the MGEs, antibiotics, pathogenic bacteria community and nonpathogenic bacteria community.

https://www.sciencedirect.com/science/article/abs/pii/S004313541830928X