台风利奇马对城市淡水系统中微生物群落和抗生素耐药性基因的影响

【背景】极端天气事件(如台风)带来的强风和降水，会给水生生态系统造成短暂和持久的影响。然而，很少有研究关注台风对水生微生物群落和抗生素耐药性基因(antibiotic resistance genes，ARGs)的影响。【目的】对台风前后城市淡水水域的微生物群落和抗性基因组成进行研究分析，更好地认识极端天气对淡水生态系统的干扰。【方法】在台风前后从4个地点采集了水样，通过宏基因组分析，检测了台风利奇马对温州休闲水域微生物群落和抗性基因的影响。除水生微生物群落和抗性基因外，还分析了每个采样点的物理、化学参数，包括温度、pH、溶解氧、叶绿素a、可溶性活性磷、硝酸盐、亚硝酸盐和铵。【结果】台风登陆后，大多数地点的pH、溶解氧和叶绿素a都有所增加。然而，台风对九山湖的影响要弱于对三垟湿地的影响。台风登陆后，变形菌门、蓝菌门和拟杆菌门的相对丰度增加，而放线菌门的相对丰度下降。在属水平上，栖湖菌的微生物多样性和相对丰度显著增加。在所有的环境因子中，铵是影响微生物群落结构的最重要的环境因子。另外，在所有样本中均检测到35个机会性致病菌类群。台风后，铜绿假单胞菌的相对丰度增加。ARGs显示了空间(采样点间)和时间(台风前后)的变化。冗余分析表明，水总无机氮是影响抗性基因分布的主要环境因子。【结论】这些发现为极端天气(如台风)如何影响淡水系统中的微生物群落和抗性基因提供了新的见解。台风登陆增加了城市淡水系统的公共安全风险，因此，检验检疫方法和手段应该前移，加强对环境健康安全的评价和分析，这将有助于减轻抗生素耐药性和致病菌扩散的风险。

Effects of typhoon Lekima on microbial communities and antibiotic resistance genes in urban freshwater systems

Background] Extreme weather events, such as typhoons, bring transient and lasting effects on aquatic ecosystems due to strong winds and precipitation. However, very few studies have focused on the effects of typhoons on aquatic microbial communities and antibiotic resistance genes (ARGs). Objective] To understand the effect of extreme weather on freshwater ecosystem, we analyzed the microbial communities and ARGs in urban freshwater before and after typhoon. Methods] Water samples were collected from four sites before and after the typhoon. The effects of Lekima on the microbial communities and ARGs in recreational waters in Wenzhou were examined by metagenomic analysis in summer, 2019. In addition to the aquatic microbial communities and ARGs, the physical and chemical parameters of water samples from each sampling site were analyzed, including temperature, pH, dissolved oxygen, chlorophyll a, soluble active phosphorus, nitrate, nitrite, andammonium. Results] The pH, dissolved oxygen, and chlorophyll a at most sites increased after the typhoon, and the typhoon had a weaker effect on Jiushan Lake than on Sanyang Wetland. The relative abundances of Proteobacteria, Cyanobacteria, and Bacteroidetes increased, while that of Actinobacteria decreased after the typhoon. At the genus level, Limnohabitans showcased significantly increased diversity and relative abundance after the typhoon. Among all the environmental factors, ammonium was the key environmental factor affecting microbial community structure. In addition, 35 opportunistic pathogen taxa were detected in all samples. The relative abundance of Pseudomonas aeruginosa, an important opportunistic pathogen, increased after the typhoon. The ARGs showed spatial (among sampling sites) and temporal (before and after the typhoon) variation. A redundancy analysis showed that water total inorganic nitrogen was the main environmental factor affecting the distribution of ARGs.Conclusion] These findings provide new insights into how extreme weather (e.g., typhoons) influences microbial communities and ARGs in freshwater system. Typhoon landing increases the public safety risk of urban freshwater system. Therefore, the testing and quarantine should be carried out in advance to strengthen the evaluation and analysis of environmental health and safety, which will help to reduce the risk of antibiotic resistance and pathogen diffusion.