Antibiotic resistance genes (ARGs) are emerging contaminants of significant concern due to their role in facilitating the spread of antibiotic resistance, especially high-risk ARGs, which are characterized by high human accessibility, gene mobility, pathogenicity, and clinical availability. Studies have shown that cross-domain interactions, such as those between consumer protists (consumers) and bacteria, can influence bacterial diversity, distribution, and function through top-down control. The consumers-bacteria interactions may also affect the occurrence and distribution of ARGs, yet this has been scarcely explored in field investigations. We conducted a city-scale investigation of ARGs, protists, and bacterial communities across each unit of the urban sewage system (USS), including 49 sewage pumping stations (SW), as well as influent (IF), activated sludge (AS), and effluent (EF) from seven wastewater treatment plants. Interestingly, consumers-bacteria interactions, as indicated by indices of bipartite relevance networks (i.e., connectedness and cohesion), increased from SW and IF to AS and EF. Structural equation modelling (SEM) revealed that consumers-bacteria interactions had a greater influence on the abundance of total ARGs and high-risk ARGs than seasonal or environmental factors. Notably, the total effects of consumers-bacteria interactions in SEM were significant (P < 0.05) and comparable in both IF and EF, even with the decrease in ARG abundance from IF to EF. This suggests a potential risk of ARG spread to the environment, facilitated by consumer protists in the EF. Additionally, the relevance network also demonstrated an increasing trend in the relationships between consumer protists and potential hosts of high-risk ARGs from raw sewage (SW and IF) to AS and EF. Overall, this study emphasizes the importance of integrating multitrophic microbial interactions to better understand and mitigate the dissemination of ARGs in sewage systems.

中文翻译：

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揭示被忽视的消费者原生生物-细菌相互作用在城市污水系统中抗生素耐药性基因传播中的关键作用


抗生素耐药基因 （ARGs） 是备受关注的新兴污染物，因为它们在促进抗生素耐药性传播方面的作用，尤其是高危 ARG，其特点是人类可及性、基因迁移性、致病性和临床可用性高。研究表明，跨域相互作用，例如消费者原生生物（消费者）和细菌之间的相互作用，可以通过自上而下的控制来影响细菌的多样性、分布和功能。消费者与细菌的相互作用也可能影响 ARGs 的发生和分布，但这在田间调查中几乎没有得到探索。我们对城市污水系统 （USS） 每个单元的 ARG、原生生物和细菌群落进行了城市规模的调查，包括 49 个污水泵站 （SW） 以及来自 7 个污水处理厂的进水 （IF）、活性污泥 （AS） 和出水 （EF）。有趣的是，消费者与细菌的相互作用，如二分相关性网络指数（即连通性和内聚力）所示，从 SW 和 IF 增加到 AS 和 EF。结构方程模型 （SEM） 显示，与季节性或环境因素相比，消费者与细菌的相互作用对总 ARG 和高风险 ARG 丰度的影响更大。值得注意的是，SEM 中消费者-细菌相互作用的总体影响是显着的 （P < 0.05），并且在 IF 和 EF 中相当，即使从 IF 到 EF 的 ARG 丰度降低。这表明 ARG 存在传播到环境的潜在风险，而 EF 中的消费者原生生物则促成了这一点。 此外，相关性网络还表明，消费者原生生物与高风险 ARG 的潜在宿主之间的关系呈增长趋势，从未经处理的污水 （SW 和 IF） 到 AS 和 EF。总体而言，本研究强调了整合多营养微生物相互作用的重要性，以更好地了解和减轻 ARGs 在污水系统中的传播。