Investigating the debrominations of a subset of brominated flame retardants by biogenic reactive sulfur species. (April 2023)

• Record Type: Journal Article
• Authors: Wu, Xiaohua; Fan, Kaili; Wang, Qingda; Cao, Qun; Chen, Chuan; Xun, Luying; Liu, Huaiwei
• Is Part Of: Environment international. Volume 174(2023)
• Publication Date: 2023-04
• Subjects: Brominated flame retardants -- Reactive sulfur species -- Debromination -- HBCD -- TBECH -- TBP; Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2023.107873
• Languages: English
• ISSNs: 0160-4120

Abstract

Graphical abstract: Highlights: Reactive sulfur species react with brominated flame retardants to release bromide. Both substitutive and reductive debromination reactions can occur. Reactive sulfur species-producing bacteria promote the debromination. Abstract: Brominated flame retardants (BFRs) are persistent organic pollutants. Many bacteria are able to debrominate BFRs, but the underlying mechanism is unclear. Herein, we discovered that reactive sulfur species (RSS), which have strong reductive activity and are commonly present in bacteria, might be one of the reasons leading to such ability. Experiments performed with RSS (H2 S and HSSH) and BFRs indicated that RSS can debrominate BFRs via two different mechanisms simultaneously: the substitutive debromination that generates thiol-BFRs and the reductive debromination that generates hydrogenated BFRs. Debromination reactions rapidly happened under neutral pH and ambient temperature, and the debromination degree was around 30% − 55% in one hour. Two Pseudomonas strains, Pseudomonas sp . C27 and Pseudomonas putida B6-2 both produced extracellular RSS and showed debromination activity. C27 debrominated HBCD, TBECH, and TBP by 5.4%, 17.7%, and 15.9% in two days. Whereas, B6-2 debrominated the three BFRs by 0.4%, 0.6%, and 0.3% in two days. The two bacteria produced different amounts and species of RSS, which were likely responsible for the contrasted degrees of the debromination. Our finding unveiled a novel, non-enzymatic debromination mechanism that many bacteria may possess. RSS producing bacteria have potentials to contribute to bioremediation of BFRs-polluted environments.