Anaerobic biodegradation of acetochlor by acclimated sludge and its anaerobic catabolic pathway
Anaerobic biodegradation of acetochlor by acclimated sludge and its anaerobic catabolic pathway
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DOI：
10.1016/j.scitotenv.2020.141122
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发表时间：
2020-12-15
影响因子：
9.8
通讯作者：
He, Jian
中科院分区：
文献类型：
--
作者：
Liu, Junwei;Zhang, Xuan;He, Jian
乙草胺是一种氯乙酰胺类除草剂，近几十年来被广泛用于杂草控制。其残留物在环境中造成的污染引起了严重关切。乙草胺的好氧降解已经得到了很好的研究，但是，很少有人知道它的厌氧降解。在连续流厌氧反应器中，通过压力驯化获得了高乙草胺降解率的厌氧污泥。乙草胺的降解动力学符合一级动力学方程。驯化污泥对6种氯乙酰胺类除草剂的降解效率依次为甲草胺>乙草胺>异丙草胺>丁草胺>丙草胺>异丙甲草胺，且这些除草剂的N-烷氧基烷基结构对其生物降解性有显著影响。结果表明，乙草胺在厌氧条件下的降解途径为脱氯降解，共鉴定出5种代谢产物：2-乙基-6-甲基-N-（乙氧甲基）-乙酰苯胺、N-（2-甲基-6-乙基苯基）乙酰胺、N-2-乙基苯基乙酰胺、N-2-乙基苯基甲酰胺和2-乙基-N-羧基苯胺。在驯化过程中，厌氧污泥中真细菌和古细菌的群落多样性均下降，而孢菌属、孢子杆菌属、脱氯单胞菌属、固氮菌属和甲烷产气菌属的微生物丰度显著增加，并占驯化污泥的优势，且与乙草胺降解能力呈正相关。这些研究结果对于阐明乙草胺的厌氧催化机理和促进厌氧处理去除废水中乙草胺的工程应用具有重要意义。(C)2020爱思唯尔B. V.保留所有权利。
Acetochlor is a chloroacetamide herbicide that has been widely used for weed control in recent decades. The contamination from its residue in the environment has raised major serious concerns. The aerobic degradation of acetochlor has been well studied; however, little is known regarding its anaerobic degradation. In the study, anaerobic sludge with high acetochlor degradation efficiency was obtained by pressure acclimation in a continuous flow anaerobic reactor. The acetochlor degradation dynamics followed a first-order kinetic reaction equation. The acclimated sludge could degrade six chloroacetamide herbicides with the degradation efficiencies observed as alachlor > acetochlor > propisochlor > butachlor > pretilachlor > metolachlor, and the N-alkoxyalkyl structure of these herbicides significantly affected their biodegradability. Five metabolites, 2-ethyl-6-methyl-N-(ethoxymethyl)-acetanilide, N-(2-methyl-6-ethylphenyl) acetamide, N-2-ethylphenyl acetamide, N-2-ethylphenyl formamide and 2-ethyl-N-carboxyl aniline were identified, and a putative anaerobic acetochlor degradation pathway, initiated by dechlorination, was subsequently proposed. During acclimation, the community diversity of both eubacteria and archaea in the anaerobic sludge decreased, while the abundance of microbes belonging to genera Sporomusa, Sporobacterium, Dechloromonas, Azotobacter and Methanobaaerium were significantly increased and dominated the acclimated sludge, and showing a positive correlation with the acetochlor degradation capacity. These findings should be valuable to elucidate the mechanisms associated with the anaerobic catabolism of acetochlor and facilitate the engineering application of anaerobic treatment for removing acetochlor from wastewater. (C) 2020 Elsevier B.V. All rights reserved.