Abstract Background Quizalofop-p-ethyl (QPE), a unitary R configuration aromatic oxyphenoxypropionic acid ester (AOPP) herbicide, was widely used and had led to detrimental environmental effects. For finding the QPE-degrading bacteria and promoting the biodegradation of QPE, a series of studies were carried out. Results A QPE-degrading bacterial strain YC-XJ1 was isolated from desert soil and identified as Methylobacterium populi, which could degrade QPE with methanol by cometabolism. Ninety-seven percent of QPE (50 mg/L) could be degraded within 72 h under optimum biodegradation condition of 35°C and pH 8.0. The maximum degradation rate of QPE was 1.4 mg/L/h, and the strain YC-XJ1 exhibited some certain salinity tolerance. Two novel metabolites, 2-hydroxy-6-chloroquinoxaline and quinoxaline, were found by high-performance liquid chromatography/mass spectroscopy analysis. The metabolic pathway of QPE was predicted. The catalytic efficiency of strain YC-XJ1 toward different AOPPs herbicides in descending order was as follows: haloxyfop-p-methyl ≈ diclofop-methyl ≈ fluazifop-p-butyl > clodinafop-propargyl > cyhalofop-butyl > quizalofop-p-ethyl > fenoxaprop-p-ethyl > propaquizafop > quizalofop-p-tefuryl. The genome of strain YC-XJ1 was sequenced using a combination of PacBio RS II and Illumina platforms. According to the annotation result, one α/β hydrolase gene was selected and named qpeh1, for which QPE-degrading function has obtained validation. Based on the phylogenetic analysis and multiple sequence alignment with other QPE-degrading esterases reported previously, the QPEH1 was clustered with esterase family V. Conclusion M. populi YC-XJ1 could degrade QPE with a novel pathway, and the qpeh1 gene was identified as one of QPE-degrading esterase gene.How to cite: Li X, Wang J, Wu W, et al. Co-metabolic biodegradation of quizalofop-p-ethyl by Methylobacterium populi YC-XJ1 and identification of QPEH1 esterase. Electron J Biotechnol 2020;46. https://doi.org/10.1016/j.ejbt.2020.05.003 .

中文翻译：

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流行甲基杆菌YC-XJ1对喹禾灵的共代谢生物降解及QPEH1酯酶的鉴定

摘要 背景 Quizalofop-p-ethyl (QPE) 是一种单一的 R 构型芳族氧苯氧基丙酸酯 (AOPP) 除草剂，被广泛使用并导致有害的环境影响。为了寻找降解QPE的细菌，促进QPE的生物降解，进行了一系列的研究。结果从荒漠土壤中分离得到一株降解QPE的菌株YC-XJ1，鉴定为Methylobacterium populi，可通过共代谢作用与甲醇降解QPE。在 35°C 和 pH 8.0 的最佳生物降解条件下，97% 的 QPE（50 mg/L）可在 72 小时内降解。QPE的最大降解率为1.4 mg/L/h，菌株YC-XJ1表现出一定的耐盐性。两种新型代谢物，2-羟基-6-氯喹喔啉和喹喔啉，通过高效液相色谱/质谱分析发现。预测了QPE的代谢途径。菌株YC-XJ1对不同AOPPs除草剂的催化效率从高到低依次为：氟啶虫草-对甲基≈双氯灭活-甲基≈氟虫草酯-对丁基>炔草酯>氰氟草酯-丁基>喹禾灵-对乙基>虫草酯-p-乙基 > 虫草酯 > 虫草酯-对四呋喃。使用 PacBio RS II 和 Illumina 平台的组合对菌株 YC-XJ1 的基因组进行测序。根据注释结果筛选出1个α/β水解酶基因，命名为qpeh1，QPE降解功能得到验证。根据之前报道的其他 QPE 降解酯酶的系统发育分析和多序列比对，QPEH1 与酯酶家族 V 聚类。结论 M. populi YC-XJ1 可通过新途径降解 QPE，qpeh1 基因被鉴定为降解 QPE 的酯酶基因之一。引文：Li X, Wang J, Wu W, et al. 流行甲基杆菌 YC-XJ1 对喹禾灵的共代谢生物降解和 QPEH1 酯酶的鉴定。电子 J 生物技术 2020；46。https://doi.org/10.1016/j.ejbt.2020.05.003。