摘要
      河口是抗性热点，因为抗性体在这些位置从周围的河流中积累和繁殖，但抗性体的大规模生物地理学模式，特别是杀生物剂和金属抗性基因（BMRGs）及其在河口水域的驱动机制仍有待阐明。在这里，首次使用基于宏基因组学的方法研究了中国南方30个亚热带河口水域的抗性和移动性。与东部和西部地区的河口相比，珠江河口的抗生素抗性基因（ARGs）、BMRGs和移动遗传元件（MGE）的多样性和丰度更高。对多种抗生素、金属和杀生物剂具有耐药性的基因是耐药组中最丰富的基因类型。MGE的丰度（例如，intI1、IS91和tnpA）与抗性基因的总丰度高度相关，这表明它们可以作为定量估计抗性污染的潜在指标。此外，在亚热带河口形成耐药性方面，MGE比细菌群落贡献更多。理化因子（如pH）调节MGE的组成和随机组装，通过水平基因转移介导ARGs和BMRGs的共同选择。我们的研究结果具有重要意义，并为亚热带河口生态系统中ARGs和BMRGs的管理提供了参考。
Abstract
Estuaries are resistome hotspots owing to resistome accumulation and propagation at these locations from surrounding rivers, yet the large-scale biogeographic pattern of resistome, especially biocide and metal resistance genes (BMRGs) and its driving mechanisms in estuarine waters remains to be elucidated. Here, a metagenomics-based approach was firstly used to investigate resistome and mobilome profiles in waters from 30 subtropical estuaries, South China. The Pearl River estuaries had a higher diversity and abundance of antibiotic resistance genes (ARGs), BMRGs, and mobile genetic elements (MGEs) when compared with estuaries from east and west regions. Genes resistant to multiple antibiotics, metals, and biocides were the most abundant gene types in the resistome. The abundance of MGEs (e.g., intI1, IS91, and tnpA) was highly associated with the total abundance of resistance genes, suggesting their utility as potential indicators for quantitative estimations of the resistome contamination. Further, MGEs contributed more than bacterial communities in shaping the resistome in subtropical estuaries. Physicochemical factors (e.g., pH) regulated MGE composition and stochastic assembly, which mediated the co-selection of ARGs and BMRGs via horizontal gene transfer. Our findings have important implications and provide a reference on the management of ARGs and BMRGs in subtropical estuarine ecosystems.

https://www.sciencedirect.com/science/article/abs/pii/S0048969721073393