Journal
JOURNAL OF HAZARDOUS MATERIALS
Volume 361, Issue -, Pages 10-18Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jhazmat.2018.08.063
Keywords
2,6-Dibromo-4-nitrophenol; Biodegradation; Catabolic mechanism; Cupriavidus sp.; FADH(2)-dependent monooxygenase
Categories
Funding
- National Natural Science Foundation of China [31600085]
- State's Key Project of Research and Development Plan [2016YFC1402300]
- Foreword Key Priority Research Program of Chinese Academy of Sciences [QYZDB-SSW-DQC013]
- State Key Laboratory of Microbial Metabolism, Shanghai JiaoTong University [MMLKF17-04]
- Yantai Science and Technology Project [2017ZH092]
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Compound 2,6-dibromo-4-nitrophenol (2,6-DBNP) with high cytotoxicity and genotoxicity has been recently identified as an emerging brominated disinfection by-product during chloramination and chlorination of water, and its environmental fate is of great concern. To date, the biodegradation process of 2,6-DBNP is unknown. Herein, Cupriavidus sp. strain CNP-8 was reported to be able to utilize 2,6-DBNP as a sole source of carbon, nitrogen and energy. It degraded 2,6-DBNP in concentrations up to 0.7 mM, and the degradation of 2,6-DBNP conformed to Haldane inhibition model with mu(max) of 0.096 h(-1), K-s of 0.05 mM and K-i of 0.31 mM. Comparative transcriptome and real-time quantitative PCR analyses suggested that the hnp gene cluster was likely responsible for 2,6-DBNP catabolism. Three Hnp proteins were purified and functionally verified. HnpA, a FADH(2)-dependent monooxygenase, was found to catalyze the sequential denitration and debromination of 2,6-DBNP to 6-bromohydroxyquinol (6-BHQ) in the presence of the flavin reductase HnpB. Gene knockout and complementation revealed that hnpA is essential for strain CNP-8 to utiluze 2,6-DBNP. HnpC, a 6-BHQ 1,2-dioxygenase was proposed to catalyze the ring-cleavage of 6-BHQ during 2,6-DBNP catabolism. These results fill a gap in the understanding of the microbial degradation process and mechanism of 2,6-DBNP.
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