Min J, Chen W, Hu X. Biodegradation of 2,6-dibromo-4-nitrophenol by Cupriavidus sp. strain CNP-8: Kinetics, pathway, genetic and biochemical characterization.
J Hazard Mater 2019;
361:10-18. [PMID:
30176407 DOI:
10.1016/j.jhazmat.2018.08.063]
[Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 08/18/2018] [Accepted: 08/20/2018] [Indexed: 06/08/2023]
Abstract
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 μmax of 0.096 h-1, Ks of 0.05 mM and Ki 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 FADH2-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.
Collapse