Perturbation of clopyralid on bio-denitrification and nitrite accumulation: Long-term performance and biological mechanism.
Perturbation of clopyralid on bio-denitrification and nitrite accumulation: Long-term performance and biological mechanism.
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DOI：
10.1016/j.ese.2021.100144
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发表时间：
2022-01
影响因子：
12.6
通讯作者：
Guo, Jianbo
中科院分区：
文献类型：
--
作者：
Sun, Suyun;Hou, Ya-Nan;Wei, Wei;Sharif, Hafiz Muhammad Adeel;Huang, Cong;Ni, Bing-Jie;Li, Haibo;Song, Yuanyuan;Lu, Caicai;Han, Yi;Guo, Jianbo
关键词：
除草剂二氯吡啶酸（3，6-二氯-2-吡啶羧酸，CLP）的污染对生态系统构成潜在威胁。然而，目前关于CLP对生物脱氮过程的扰动作用研究普遍缺乏，其生物响应机制尚不清楚。本文系统研究了CLP长期暴露对反硝化性能和微生物动态响应的影响。结果表明，低浓度CLP（<15 mg/L）培养初期会引起亚硝酸盐的严重积累，而高浓度CLP（35-60 mg/L）培养长期后对亚硝酸盐的积累没有进一步影响。机理研究表明，CLP通过引起氧化应激和膜损伤，降低亚硝酸盐还原酶（NIR）活性，抑制代谢活性（碳代谢和氮代谢），导致亚硝酸盐积累。但在60 mg/L CLP条件下驯化80 d后，亚硝酸盐几乎没有积累。结果表明，胞外聚合物（EPS）的分泌量从15 mg/L CLP时的75.03 mg/g VSS增加到60 mg/L CLP时的109.97 mg/g VSS，增强了对微生物细胞的保护作用，提高了近红外活性和代谢活性。此外，微生物群落的多样性和丰富度经历了一个U型过程。反硝化和碳代谢相关微生物的相对丰度最初下降，然后恢复与EPS和N-酰基高丝氨酸内酯（AHL）分泌相关的微生物的富集。这些微生物保护微生物免受有毒物质的侵害，并调节它们在种间和种内的相互作用。本研究揭示了CLP连续暴露后反硝化的生物学响应机制，为含除草剂废水的分析和处理提供了正确的指导。NO2−积累显着增强初始CLP暴露。CLP可通过引起ROS产生和膜损伤抑制微生物的存活。ROS的产生降低了近红外光谱、代谢和电子传递效率。长期CLP暴露刺激EPS分泌增加。EPS的保护和微生物群落的演替恢复了反硝化作用。
The contaminant of herbicide clopyralid (3,6-dichloro-2- pyridine-carboxylic acid, CLP) poses a potential threat to the ecological system. However, there is a general lack of research devoted to the perturbation of CLP to the bio-denitrification process, and its biological response mechanism remains unclear. Herein, long-term exposure to CLP was systematically investigated to explore its influences on denitrification performance and dynamic microbial responses. Results showed that low-concentration of CLP (<15 mg/L) caused severe nitrite accumulation initially, while higher concentrations (35–60 mg/L) of CLP had no further effect after long-term acclimation. The mechanistic study demonstrated that CLP reduced nitrite reductase (NIR) activity and inhibited metabolic activity (carbon metabolism and nitrogen metabolism) by causing oxidative stress and membrane damage, resulting in nitrite accumulation. However, after more than 80 days of acclimation, almost no nitrite accumulation was found at 60 mg/L CLP. It was proposed that the secretion of extracellular polymeric substances (EPS) increased from 75.03 mg/g VSS at 15 mg/L CLP to 109.97 mg/g VSS at 60 mg/L CLP, which strengthened the protection of microbial cells and improved NIR activity and metabolic activities. Additionally, the biodiversity and richness of the microbial community experienced a U-shaped process. The relative abundance of denitrification- and carbon metabolism-associated microorganisms decreased initially and then recovered with the enrichment of microorganisms related to the secretion of EPS and N-acyl-homoserine lactones (AHLs). These microorganisms protected microbe from toxic substances and regulated their interactions among inter- and intra-species. This study revealed the biological response mechanism of denitrification after successive exposure to CLP and provided proper guidance for analyzing and treating herbicide-containing wastewater. NO2− accumulation was significantly enhanced by initial CLP exposure. CLP could inhibit microbial viability by causing ROS production and membrane damage. The generation of ROS reduced NIR, metabolism and electron transport efficiency. Long-term CLP exposure stimulated the increase of EPS secretion. The protection of EPS and succession of microbial community restored denitrification.
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