State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, Shandong, 266071, China; Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, Shandong, 266071, China.
Research Centre for Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, 300457, China.
J Environ Manage. 2023 Sep 15;342:118132. doi: 10.1016/j.jenvman.2023.118132. Epub 2023 May 30.
Sediment is thought to be a vital reservoir to spread antibiotic resistance genes (ARGs) among various natural environments. However, the spatial distribution patterns of the sedimental antibiotic resistomes around the Bohai Bay region, a river-connected coastal water ecosystem, are still poorly understood. The present study conducted a comprehensive investigation of ARGs among urban rivers (UR), estuaries (ES) and Bohai Bay (BHB) by metagenomic sequencing. Overall, a total of 169 unique ARGs conferring resistance to 15 antimicrobial classes were detected across all sediment samples. The Kruskal-Wallis test showed that the diversity and abundance of ARGs in the UR were all significantly higher than those in the ES and BHB (p < 0.05 and p < 0.01), revealing the distance dilution of the sedimental resistomes from the river to the ocean. Multidrug resistance genes contained most of the ARG subtypes, whereas rifamycin resistance genes were the most abundant ARGs in this region. Our study demonstrated that most antimicrobial resistomes were highly accumulated in urban river sediments, whereas beta-lactamase resistance genes (mainly PNGM-1) dramatically increased away from the estuary to the open ocean. The relative abundance of mobile genetic elements (MGEs) also gradually decreased from rivers to the coastal ocean, whereas the difference in pathogenic bacteria was not significant in the three classifications. Among MGEs, plasmids were recognized as the most important carriers to support the horizontal gene transfer of ARGs within and between species. According to co-occurrence networks, pathogenic Proteobacteria, Actinobacteria, and Bacteroidetes were recognized as potential and important hosts of ARGs. Heavy metals, pH and moisture content were all recognized as the vital environmental factors influencing the distribution of ARGs in sediment samples. Overall, the present study may help to understand the distribution patterns of ARGs at a watershed scale, and help to make effective policies to control the emergence, spread and evolution of different ARG subtypes in different habitats.
沉积物被认为是在各种自然环境中传播抗生素耐药基因 (ARGs) 的重要储库。然而，对于渤海湾地区这样一个河流连接的沿海水生态系统，沉积物抗生素抗性组的空间分布模式仍知之甚少。本研究通过宏基因组测序对城市河流 (UR)、河口 (ES) 和渤海湾 (BHB) 中的 ARGs 进行了全面调查。总的来说，在所有沉积物样本中检测到了 169 种独特的 ARGs，这些 ARGs 赋予了对 15 种抗菌类别的抗性。Kruskal-Wallis 检验显示，UR 中的 ARG 多样性和丰度均明显高于 ES 和 BHB（p<0.05 和 p<0.01），表明从河流到海洋，沉积物抗性组的距离稀释作用。多药耐药基因包含了大多数 ARG 亚型，而 rifamycin 耐药基因是该区域最丰富的 ARG。本研究表明，大多数抗菌抗性组高度聚集在城市河流沉积物中，而β-内酰胺酶耐药基因（主要是 PNGM-1）从河口向开阔海域急剧增加。从河流到沿海海洋，移动遗传元件 (MGE) 的相对丰度也逐渐降低，而三种分类中的致病菌差异不显著。在 MGE 中，质粒被认为是支持 ARGs 在种内和种间水平基因转移的最重要载体。根据共现网络，致病性 Proteobacteria、Actinobacteria 和 Bacteroidetes 被认为是 ARGs 的潜在和重要宿主。重金属、pH 值和含水量均被认为是影响沉积物样本中 ARG 分布的重要环境因素。总的来说，本研究有助于了解流域尺度上 ARG 的分布模式，并有助于制定有效的政策来控制不同生境中不同 ARG 亚型的出现、传播和进化。
