摘要

       在这项研究中，在中国海河沉积物样品中定量了五类抗生素抗性基因（ARGs），丰度范围从 1.39 × 104 到 1.58 × 1010 拷贝/克干重。同时，还通过过滤交配分析从这些样品中分离出抗生素抗性接合质粒。总共分离出 202 个转接合子并测试了它们的抗生素抗性表型，其中观察到 26 种不同类型的接合质粒。这些质粒中的大多数显示出多重抗性表型，最普遍的抗性是四环素抗性和磺胺抗性。此外，我们测试了这些质粒的转移频率，确定了它们的基因型，然后将质粒携带的 ARGs 与其在海河中的相应丰度进行了比较。大多数分离的质粒表现出向受体菌株大肠杆菌 J53 的高转移频率。从海河市区分离的质粒比农村有更高的转移频率。对质粒基因型、ARG丰度和质粒测序的综合分析结果证实，大部分质粒携带的ARGs是海河中的优势基因。因此，从海河中分离的接合质粒对海河中ARGs的传播、丰度和空间分布起着至关重要的作用，尤其是一些不常见的ARGs，如blaGES-1。这项研究将有助于增加对环境中接合质粒介导的 ARG 传播的认识。

       In this study, five classes of antibiotic resistance genes (ARGs) were quantified in sediment samples of Haihe River, China, with abundance ranging from 1.39 × 104 to 1.58 × 1010 copies/g dry weight. Meanwhile, antibiotic resistant conjugative plasmids were also isolated from these samples through filter mating assays. In total, 202 transconjugants were isolated and tested for their antibiotic resistance phenotypes, among which 26 different types of conjugative plasmids were observed. The majority of these plasmids showed a multi-resistant phenotype and the most prevalent resistance was tetracycline resistance and sulfonamide resistance. Furthermore, we tested the transfer frequencies of these plasmids, determined their genotypes and then compared the plasmid-borne ARGs with their corresponding abundance in Haihe River. Most of the isolated plasmids exhibited high transfer frequencies to the recipient strain Escherichia coli J53. Plasmids isolated from the urban areas of Haihe River have higher transfer frequencies than the rural areas. Results from comprehensive analysis of plasmid genotypes, ARG abundance and plasmid sequencing confirmed that most of the plasmid-borne ARGs were the dominant genes in the Haihe River. Therefore, conjugative plasmids isolated from the Haihe River plays a crucial role in the dissemination, abundance and spatial distribution of ARGs in Haihe River, especially some unfrequent ARGs like blaGES-1. This study will help to increase the knowledge on the conjugative plasmid-mediated ARG propagation in the environment.

https://www.sciencedirect.com/science/article/abs/pii/S0043135416309903