Anthropogenic activities significantly impact the elemental cycles in aquatic ecosystems, with the N-cycling playing a critical role in potential nutrient turnover and substance cycling. We hypothesized that measures to prevent COVID-19 transmission profoundly altered the nitrogen cycle in riverine ecosystems. To investigate this, we re-analyzed metagenomic data and identified 60 N-cycling genes and 21 host metagenomes from four urban reaches (one upstream city, Wuhan, and two downstream cities) along the Yangtze River. Our analyses revealed a marked decrease in the abundance of bacterial ammonia monooxygenase genes, as well as in the host, ammonia-oxidizing autotrophic , followed by a substantial recovery post-pandemic. We posited that discharge of sodium hypochlorite (NaOCl) disinfectant may be a primary factor in the reduction of N-cycling process. To test this hypothesis, we exposed pure cultures of to NaOCl to explore the microbial stress response. Results indicated that NaOCl exposure rapidly compromised the cell structure and inhibited ammonia oxidation of , likely due to oxidative stress damage and reduced expression of nitrogen metabolism-related ammonia monooxygenase. Using the functional tagging technique, we determined that NaOCl directly destroyed the ammonia monooxygenase protein and DNA structure. This study highlights the negative impacts of chlorine disinfectants on the function of aquatic ecosystems and elucidates potential mechanisms of action.

中文翻译：

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COVID-19爆发后消毒剂引起的水生生态系统微生物氮循环过程中的氨氧化破坏

人类活动显着影响水生生态系统的元素循环，其中氮循环在潜在的养分周转和物质循环中发挥着关键作用。我们假设，防止 COVID-19 传播的措施深刻改变了河流生态系统的氮循环。为了研究这一问题，我们重新分析了宏基因组数据，并从长江沿线的四个城市河段（上游城市武汉和下游城市两个城市）鉴定了 60 个氮循环基因和 21 个宿主宏基因组。我们的分析显示，细菌氨单加氧酶基因以及宿主氨氧化自养酶基因的丰度显着下降，随后在大流行后大幅恢复。我们认为次氯酸钠（NaOCl）消毒剂的排放可能是氮循环过程减少的主要因素。为了检验这一假设，我们将纯培养物暴露于 NaOCl 中以探索微生物的应激反应。结果表明，NaOCl 暴露迅速损害了细胞结构并抑制了氨氧化，这可能是由于氧化应激损伤和氮代谢相关氨单加氧酶的表达减少所致。利用功能标记技术，我们确定NaOCl直接破坏氨单加氧酶蛋白和DNA结构。这项研究强调了氯消毒剂对水生生态系统功能的负面影响，并阐明了潜在的作用机制。