Aquatic EcoHealth Group, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Aquatic EcoHealth Group, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
Sci Total Environ. 2019 Jul 10;673:533-540. doi: 10.1016/j.scitotenv.2019.04.031. Epub 2019 Apr 4.
Although seasonality is a key driver of environmental fluctuation in aquatic ecosystems, there exists limited knowledge on the factors controlling the distribution of antibiotic resistance genes (ARGs) across seasons at a watershed scale. Here we used high-throughput quantitative PCR to quantify 285 ARGs conferring resistance to most major classes of antibiotics, reveal their spatial and seasonal distribution patterns, and depict the underlying mechanisms in a subtropical riverine ecosystem under low and high human pressures, in Xiamen city, southeast China. Our results showed that spatial differences in ARG richness and abundance overwhelmed their seasonal variations, with only ARGs that confer resistance to sulfonamide and vancomycin being significantly different across seasons. Only a few abundant ARGs (19 ARGs) could contribute to >70% of the total ARGs abundance and were found in all seasons. The significantly higher number of ARGs in the summer rainy period than other seasons coincided with high number of significant edges in ARG co-occurrence networks. Summer rainfall had strong dilution effect on ARGs in upstream waters and enrichment effect in downstream waters. The variance partitioning analysis indicated that the environment explained larger variance of ARG profiles than mobile genetic elements (MGEs), spatial predictors and the rainfall. Nevertheless, strong and significant correlations between transposase gene absolute abundance and aminoglycoside, chloramphenicol, MLS, multidrug and tetracycline classes of resistance genes inferred the role of MGEs on ARG distribution. Overall, our results imply that the modelling and management of ARGs in highly dynamic ecosystems could be better implemented by considering priority genes that dominate at spatial and seasonal gradients.
尽管季节性是水生生态系统环境波动的关键驱动因素，但对于在流域尺度上控制抗生素耐药基因（ARGs）分布的因素，我们的了解仍然有限。在这里，我们使用高通量定量 PCR 来量化 285 个赋予抗生素抗性的 ARGs，揭示它们在空间和季节性分布模式，并描绘在中国东南部厦门市一个亚热带河流生态系统中，在低人和高人为压力下的潜在机制。我们的结果表明，ARG 丰富度和丰度的空间差异超过了季节性变化，只有对磺胺类药物和万古霉素具有抗性的 ARGs 在季节间存在显著差异。只有少数丰度较高的 ARGs（19 个 ARGs）可以贡献总 ARGs 丰度的>70%，并且在所有季节都存在。夏季雨季比其他季节具有更多的 ARGs，这与 ARG 共现网络中显著边缘数量较多相一致。夏季降雨对上游水体中的 ARGs 具有强烈的稀释作用，对下游水体具有强烈的富集作用。方差分解分析表明，环境比移动遗传元件（MGEs）、空间预测因子和降雨量能更好地解释 ARG 谱的变异性。然而，转座酶基因绝对丰度与氨基糖苷类、氯霉素、MLS、多药和四环素类抗性基因之间的强烈和显著相关性推断了 MGEs 在 ARG 分布中的作用。总体而言，我们的研究结果表明，在高度动态的生态系统中，通过考虑在空间和季节性梯度上占主导地位的优先基因，可以更好地对 ARGs 进行建模和管理。
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