Citrobacter sp. Y3 harbouring novel gene HBCD-hd-1 mineralizes hexabromocyclododecane via new metabolic pathways according to multi-omics characterization

• Published in: Journal of hazardous materials 2023-01, Vol.442, p.130071-130071, Article 130071
• Main Authors: Peng, Xingxing, Li, Tianyu, Zheng, Qihang, Lu, Yingyuan, He, Yuzhe, Tang, Yetao, Qiu, Rongliang
• Format: Article
• Language: English
• Subjects: Catabolic pathway; Hexabromocyclododecane; Identification of functional gene; Mineralization; Multi-omics
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2022.130071

Hexabromocyclododecane (HBCD) is a typical persistent organic pollutant that is widely detected in the environment. Despite the significant efforts put into its mineralisation, there is still a lack of microorganism resources that can completely mineralise HBCD. Stable isotope analysis revealed that the Citrobacter sp. Y3 can use [13C]HBCD as its sole carbon source and degrade or even mineralise it into 13CO2, with a maximum conversion rate of 100% in approximately 14 days. Strain Y3 could completely mineralise HBCD, which it used as its only carbon source, and six debromination enzymes related to HBCD degradation were found in Y3, including haloalkane dehalogenase (DhaA), haloacid dehalogenase (HAD), etc. A functional gene named HBCD-hd-1, encoding a HAD, was found to be upregulated during HBCD degradation and heterologously expressed in Escherichia coli. Recombinant E. coli with the HBCD-hd-1 gene transformed the typical intermediate 4-bromobutyric acid to 4-hydroxybutanoic acid and showed excellent degradation performance on HBCD, accompanied by nearly 100% bromine (Br) ion generation. The expression of HBCD-hd-1 in Y3 rapidly accelerated the biodegradation of HBCD. With HBCD as its sole carbon source, strain Y3 could potentially degrade HBCD, especially in a low-nutrient environment. [Display omitted] •The Citrobacter sp. Y3 was the only strain which could completely mineralize HBCD as the sole carbon source.•Reconstruction of HBCD catabolic pathway using genomic, proteomic, and metabolic analysis.•A new functional gene named HBCD-hd-1 encoding a haloacid dehalogenase was firstly cloned and heterologously expressed.•The expression of HBCD-hd-1 in strain Y3 rapidly accelerated the process of HBCD mineralization.