摘要

       快速的城市化导致城市水生生态系统中普遍存在抗生素抗性基因（ARGs）。然而，关于 ARG 剖面和负责它们在城市景观泻湖系统中组装的力量的信息有限。在这里，我们采用高通量定量 PCR (HT-qPCR) 来表征中国云当泻湖表层和核心沉积物中 ARG 的空间变化。结果表明，与原始参考西藏湖泊沉积物相比，泻湖沉积物中ARGs的平均丰富度和绝对丰度分别高出11倍和53倍，突出了人为活动在ARG污染中的作用。共生网络分析表明，属于 Alpha-、Deltaproteobacteria、Bacteroidetes、Euryarchaeota、Firmicutes 和 Synergistetes 的各种厌氧原核属是 ARG 的潜在宿主。偏最小二乘路径建模 (PLS-PM) 分析揭示了物理化学因素和重金属分别通过生物因素对泻湖 ARG 剖面的正面和负面间接影响。水平（由移动遗传元件介导）和垂直（由原核生物群落介导）基因转移可能分别对驱动 ARG 的丰度和组成贡献最大。此外，中性群落模型表明沉积物 ARG 群落的组装受确定性和随机过程共同控制。总体而言，这项研究为城市泻湖系统底栖栖息地中 ARG 的多样性和分布以及 ARG 传播和增殖的潜在机制提供了新的见解。

       Rapid urbanization has resulted in pervasive occurrence of antibiotic resistance genes (ARGs) in urban aquatic ecosystems. However, limited information is available concerning the ARG profiles and the forces responsible for their assembly in urban landscape lagoon systems. Here, we employed high-throughput quantitative PCR (HT-qPCR) to characterize the spatial variations of ARGs in surface and core sediments of Yundang Lagoon, China. The results indicated that the average richness and absolute abundance of ARGs were 11 and 53 times higher in the lagoon sediments as compared to pristine reference Tibetan lake sediments, highlighting the role of anthropogenic activities in ARG pollution. Co-occurrence network analysis indicated that various anaerobic prokaryotic genera belonging to Alpha-, Deltaproteobacteria, Bacteroidetes, Euryarchaeota, Firmicutes and Synergistetes were the potential hosts of ARGs. The partial least squares-path modeling (PLS-PM) analysis revealed positive and negative indirect effects of physicochemical factors and heavy metals on the lagoon ARG profiles, via biotic factors, respectively. The horizontal (mediated by mobile genetic elements) and vertical (mediated by prokaryotic communities) gene transfer may directly contribute the most to drive the abundance and composition of ARGs, respectively. Furthermore, the neutral community model demonstrated that the assembly of sediment ARG communities was jointly governed by deterministic and stochastic processes. Overall, this study provides novel insights into the diversity and distribution of ARGs in the benthic habitat of urban lagoon systems and underlying mechanisms for the spread and proliferation of ARGs.

https://www.sciencedirect.com/science/article/abs/pii/S1001074220303909