Biotechnology Bulletin ›› 2022, Vol. 38 ›› Issue (2): 113-122.doi: 10.13560/j.cnki.biotech.bull.1985.2021-0243

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Isolation and Identification of Nicosulfuron Degrading Strain Chryseobacterium sp. LAM-M5 and Study on Its Degradation Pathway

MA Qing-yun1,2(), JIANG Xu1, LI Qing-qing1,2, SONG Jin-long3, ZHOU Yi-qing1, RUAN Zhi-yong1,4,5()   

  1. 1. CAAS-CIAT Joint Laboratory in Advanced Technologies for Sustainable Agriculture,Institute of Agricultural Resources and Regional Planning,Chinese Academy of Agricultural Sciences,Beijing 100081
    2. Graduate School of Chinese Academy of Agricultural Sciences,Beijing 100081
    3. Chinese Academy of Fishery Sciences,Beijing 100141
    4. College of Resources and Environment,Tibet Agricultural and Animal Husbandry University,Linzhi 860000
    5. College of Life Sciences,Yantai University,Yantai 264005
  • Received:2021-03-03 Online:2022-02-26 Published:2022-03-09
  • Contact: RUAN Zhi-yong E-mail:1065178170@qq.com;ruanzhiyong@caas.cn

Abstract:

In order to obtain more nicosulfuron-degrading bacterial resources,the activated sludge samples from a nicosulfuron manufacturer in Hefei city were used for study object,from which an isolated and screened strain grew well with glucose as sole carbon source and nicosulfuron as sole nitrogen source. Based on its phenotypic characteristics,the 16S rRNA gene sequence similarity,the values of DNA-DNA hybridization and average nucleotide identity,it was identified as Chryseobacterium lacus LAM-M5. This strain degraded 92.39% of 50 mg/L nicosulfuron within 7 d. Liquid chromatography mass spectrometry was used to detect and identify the metabolites after mixing culture of LAM-M5 and nicosulfuron,and 5 major substances were detected. The metabolic pathway of LAM-M5 degrading nicosulfuron was primarily speculated based on the chemical structure and characteristics of intermediates. High performance liquid chromatography was employed to isolate and identify the acids generated during the degradation of nicosulfuron by strain LAM-M5,and the results showed that L-malic acid was predominant. It was deduced that strain LAM-M5 metabolized the glucose into L-malic acid when its growth was stressed by the nicosulfuron,from which the environmental pH decreased and the nicosulfuron hydrolyzed,thus the stress was released. Through the analysis of the whole genome sequence of strain LAM-M5,7 annotated genes that may contribute to the degradation of nicosulfuron were predicted. The results reveal that strain LAM-M5 has excellent ability of degrading nicosulfuron and may have promising application potential in the microbial remediation of nicosulfuron -polluted environment.

Key words: nicosulfuron, Chrysobacterium, microbial degradation, metabolic pathway