摘要

      河口位于陆地/淡水和海洋生态系统之间，从陆地来源获得大量污染物输入，并受到人类活动的很大影响。然而，对河口环境中细胞外抗药性基因（eARGs）和细胞内抗药性基因（iARGs）的联合研究却鲜有人关注。本研究采用高通量定量PCR技术，对海河河口沉积物中的eARGs和iARGs进行了分析，探讨了它们与可移动基因元件（MGEs）、细菌群落和环境因子的关系。结果表明，河口沉积物eARGs的丰度在9.06×106～1.32×108拷贝/g之间，iARGs丰度在3.31×107～2.93×108拷贝/g之间，是eARGs和iARGs的主要研究热点。此外，在海河河口地区，尤其是沿海地区，多重耐药性基因多样性强，数量丰富。万古霉素和碳青霉烯酶高丰度耐药基因可能对人类健康构成潜在威胁。盐度改变了细菌群落的组成和结构。部分冗余分析表明，细菌群落和MGEs是河口沉积物ARG变异的主要驱动因子。本研究概述了海河河口地区eARG和iARG的分布，并提出了河口生态系统控制污染物的必要性。

      Estuaries lie between terrestrial/freshwater and marine ecosystems, receive considerable pollutant input from land-based sources, and are considerably influenced by human activities. However, little attention has been paid to combined research on extracellular antibiotic resistance genes (eARGs) and intracellular ARGs (iARGs) in the estuarine environment. In this study, we profiled eARGs and iARGs in sediments from Haihe Estuary, China by adopting high-throughput quantitative PCR and investigated their relationship with mobile genetic elements (MGEs), the bacterial community and environmental factors. The results showed that the abundance of eARGs ranged from 9.06 × 10⁶ to 1.32 × 10⁸ copies/g and that of iARGs ranged from 3.31 × 10⁷ to 2.93 × 10⁸ copies/g, indicating that estuarine sediments were key hotspots of eARGs and iARGs. Additionally, multidrug resistance genes were both highly diverse and abundant in Haihe Estuary, especially in coastal samples. The high abundance of vancomycin and carbapenemase resistance genes may pose a potential health risk to human. Salinity altered the composition and structure of the bacterial community. Partial redundancy analysis showed that the bacterial community and MGEs appeared to be the major drivers of ARG variance in estuarine sediment. This study provides an overview of the distribution of eARG and iARG along the Haihe Estuary and draws attention to the need to control pollutants in estuary ecosystems.

      https://www.sciencedirect.com/science/article/pii/S0160412019314722