宏基因组分析城市休闲水域九山湖的微生物群落结构和抗性基因

【背景】城市水环境正面临着严峻的抗生素抗性基因(antibiotic resistance genes，ARGs)污染。然而关于城市休闲水域中ARGs的研究较少。【目的】对城市休闲水域夏冬季节的微生物群落和抗性基因组成进行研究分析，促进对休闲水域水生生态系统的认识。【方法】基于高通量测序技术，对休闲湖泊九山湖夏季和冬季的微生物及ARGs组成进行分析。【结果】在夏季和冬季样本中分别检测到148门和152门。变形菌门(Proteobacteria)和放线菌门(Actinobacteria)是两个季节样本的主要菌门。夏季优势属为聚球藻属(Synechococcus)，冬季优势属为Liminohabitans。此外，共鉴定出449种抗性基因型(304种是两个季节所共有的抗性基因，66种是夏季特有的抗性基因，79种是冬季特有的抗性基因)。夏季样本中ARGs的相对丰度显著高于冬季。MCR-1.2和BcI分别是夏季和冬季水样的主要ARGs。九山湖样本检测到的抗性基因的耐药机制主要是抗生素外排、抗生素失活或抗生素靶位改变。冗余分析(redundancy analysis，RDA)和典型对应分析(canonical correspondence analysis，CCA)结果表明，环境因子与微生物群落和抗性基因的分布显著相关。【结论】九山湖冬季和夏季的微生物群落结构和抗性基因组成存在明显差异，为进一步认识和了解城市休闲水生生态系统的结构提供了有用的信息，并强调了水体的ARGs污染可能造成的健康危害。

Metagenomic analysis of the microbial community and antibiotic resistance genes in an urban recreational lake, Jiushan Lake

Background] Urban water is facing excessive antibiotic resistance genes (ARGs) contamination. However, few studies have studied the occurrence of ARGs in urban recreational waters. Objective] To analyze the microbial community and resistance gene composition in urban recreational waters between summer and winter, for the understanding of aquatic ecosystem in recreational waters. Methods] We determined the summer and winter microbial and ARGs composition of Jiushan Lake, an urban recreational lake, using high-throughput sequencing technology. Results] The study revealed the existence of 148 and 152 phyla in summer and winter samples, respectively. Proteobacteria and Actinobacteria were the two predominant phyla in both seasons. The dominant genus in summer was Synechococcus, while the dominant genus in winter was Liminohabitans. A total of 449 ARGs were identified (304 shared by both seasons, 66 summer-exclusive, and 79 winter-exclusive). In contrast to the number of ARGs, their abundance was higher in summer samples. MCR-1.2 and BcI were the predominant ARGs in summer and winter water samples, respectively. The resistance mechanisms of the detected ARGs were mainly antibiotic efflux, antibiotic inactivation, or antibiotic target alteration. The results of redundancy analysis and canonical correspondence analysis showed that environmental factors were significantly correlated with the distribution of microbial community and resistance genes. Conclusion] The microbial community structure and resistance gene composition are significantly different between winter and summer in Jiushan Lake. The results provide useful information toward a more comprehensive understanding of the structure of urban recreational aquatic ecosystems and also highlight the potential health hazards resulting from their ARGs contamination.