Biodegradation of diphenyl ether herbicide lactofen by Bacillus sp. YS-1 and characterization of two initial degrading esterases
Biodegradation of diphenyl ether herbicide lactofen by Bacillus sp. YS-1 and characterization of two initial degrading esterases
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芽孢杆菌对二苯醚除草剂乳酚的生物降解。
DOI：
10.1016/j.scitotenv.2021.151357
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发表时间：
2021-11-27
影响因子：
9.8
通讯作者：
Huang, Xing
中科院分区：
文献类型：
--
作者：
Shang, Na;Chen, Lingling;Huang, Xing
近年来，二苯醚除草剂乳草醚的广泛使用引起了严重的环境问题。因此，迫切需要对环境中的乳酚进行解毒和消除。在本研究中，乳酸乙酯降解菌为芽孢杆菌。分离到一株降解率为97.6%的YS-1菌株，15h内降解率为50 mg/L乳酚，乳酚的酯键被水解生成氨基氟醚，硝基被还原为氨基，生成氨基氟芬。最后，氨基被乙酰化，生成了乙酰化的氨基氟醚，这是一种新的乳酸降解的最终产物。乙酰氨基氟草醚对黄瓜和高粱的根系和幼苗生长的毒性明显低于乳草醚。克隆并表达了两个酯酶基因ROE和油菜，这两个基因编码的两种酯酶是乳酸乙酯水解酶和阿希氟苯酯酶。RhoE和油菜编码的氨基酸序列与已知酯酶的同源性分别为27.78%和88.21%。RhoE和油菜降解乳苯醚的最适温度分别为35℃和25℃，两种酯酶的最适pH值均为8.0。RhoE和油菜均优先降解(S)-(+)-内酯、(S)-(-)-精草灵和(S)-(-)-甲基三氯杀草净。本研究为除草剂污染土壤中乳草醚的去除和土壤的生物修复提供了菌种和水解酶资源。(C)2021年爱思唯尔B.V.保留所有权利。
The extensive use of the diphenyl ether herbicide lactofen in recent years has caused serious environmental prob-lems. Therefore, detoxification and elimination of lactofen from the environment are urgently required. In this study, the lactofen-degrading strain Bacillus sp. YS-1 was isolated, which achieved a 97.6% degradation rate of 50 mg/L lactofen within 15 h. The ester bond of lactofen was hydrolyzed, which generated acifluorfen, and then, the nitro group was reduced to the amino group, which generated aminoacifluorfen. Finally, the amino group was acetylated, which formed acetylated aminoacifluorfen, a novel end product in the degradation of lactofen. The toxicity of acetylated aminoacifluorfen to the root and seedling growth of cucumber and sorghum was significantly decreased compared with that of lactofen. The two esterase genes rhoE and rapE, encoding two esterases responsible for lactofen hydrolysis to acifluorfen, were cloned and expressed. The amino acid sequences encoded by rhoE and rapE were 27.78% and 88.21% identical with known esterases, respectively. The optimum temperatures for RhoE and RapE degradation of lactofen were 35 degrees C and 25 degrees C, respectively, and both esterases displayed maximal activity at pH 8.0. Both RhoE and RapE prioritized the degradation of (S)-(+)-lactofen, (S)-(-)-quizalofop-ethyl, and (S)-(-)-diclofop-methyl. This study provided the resources of bacterial strain and hydrolyzing enzyme for the removal of lactofen from the environment and the bioremediation of herbicide-contaminated soil. (c) 2021 Elsevier B.V. All rights reserved.