上海沙田湖养殖区及周边水体中氟喹诺酮类抗性基因的分布特征及其与环境因子关系

集约化水产养殖区常被认为是水体抗生素和抗性基因的主要潜在来源,然而对其该类水体中抗生素和抗性基因污染情况的研究仍相对匮乏.本文以上海市沙田湖养殖区及周边水体为调查对象,利用宏基因组学高通量测序技术,于2020年9月对水体中的氟喹诺酮类抗生素(fluoroquinolones,FQs)和氟喹诺酮类抗性基因(fluoroquinolones antibiotic resistance genes,FQs-ARGs)的种类和丰度进行了调查,并利用多元统计分析方法研究了水体理化因子和FQs对FQs-ARGs的影响.结果表明,沙田湖养殖区及周边水体共检测出5类耐药机制、共46种FQs-ARGs,其中各水体共有基因为44种.抗性基因mfd和patA在养殖水体和周边水体中均为优势抗性基因,抗生素抗性基因变异或突变为优势耐药机制.养殖水体和周边河湖水体、不同养殖品种水体之间FQs-ARGs的平均丰度无显著差异(P＞0.05).偏冗余分析(pRDA)表明,除了诺氟沙星和环丙沙星2种抗生素外,水体电导率(Spc)、总磷(TP)、总氮(TN)、氨氮(NH4+-N)、溶解氧(DO)、pH和叶绿素a(Chl-a)等环境因子是影响水体中FQs-ARGs组成与分布的关键性因子,且非抗生素因子的总贡献率远高于抗生素.

Investigation on Fluoroquinolone Resistance Genes in the Intensive Aquaculture Area of Shatianhu Intensive Aquiculture Farm and Surrounding Waterbodies in Shanghai, China

Intensive aquaculture areas are often considered to be an important potential source of antibiotics and resistance genes in water bodies. However, the contamination of antibiotics and resistance genes in this type of water remains largely uninvestigated. In this study, the type and abundance of fluoroquinolones (FQs) and fluoroquinolones antibiotic resistance genes (FQs-ARGs) were investigated in Shatianhu intensive aquiculture farm and the surrounding water bodies in September 2020 by using metagenomics high-throughput sequencing technology. Furthermore, the influence of water physical and chemical factors and FQs on FQs-ARGs was studied by using multivariate statistical analysis methods. The results showed that there were five types of resistance mechanisms and 46 kinds of FQs-ARGs in the culture area of Shatianhu intensive aquiculture farm and the surrounding water bodies, and there were 44 genes in each water body. Both mfd and patA were dominant resistance genes in the aquaculture water and surrounding water bodies, and variation or mutation of antibiotic resistance genes was the dominant resistance mechanism. Moreover, there was no significant difference in the average abundance of FQs-ARGs among the aquaculture water bodies, the surrounding rivers and lakes, and water bodies of different culture species. The result of partial canonical ordination analysis (pRDA) showed that in addition to norfloxacin and ciprofloxacin, specific conductance (Spc), total phosphorus (TP), total nitrogen (TN), ammonia nitrogen (NH₄⁺-N), dissolved oxygen (DO), pH, and Chlorophyll a (Chl-a) were key factors that affected the composition and distribution of FQs and ARGs in water bodies, and the total contribution rate of the latter was far higher than that of antibiotics themselves.