Investigating the debrominations of a subset of brominated flame retardants by biogenic reactive sulfur species

Xiaohua Wu; Kaili Fan; Qingda Wang; Qun Cao; Chuan Chen; Luying Xun; Huaiwei Liu

doi:10.1016/j.envint.2023.107873

Investigating the debrominations of a subset of brominated flame retardants by biogenic reactive sulfur species

Environ Int. 2023 Apr:174:107873. doi: 10.1016/j.envint.2023.107873. Epub 2023 Mar 11.

Authors

Xiaohua Wu¹, Kaili Fan², Qingda Wang¹, Qun Cao¹, Chuan Chen², Luying Xun³, Huaiwei Liu⁴

Affiliations

¹ State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266200, China.
² State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, Heilongjiang Province 150090, China.
³ State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266200, China; School of Molecular Biosciences, Washington State University, Pullman, WA 991647520, USA. Electronic address: luying_xun@vetmed.wsu.edu.
⁴ State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266200, China. Electronic address: liuhuaiwei@sdu.edu.cn.

PMID: 36933304
DOI: 10.1016/j.envint.2023.107873

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 (H₂S 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.

Keywords: Brominated flame retardants; Debromination; HBCD; Reactive sulfur species; TBECH; TBP.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biodegradation, Environmental
Flame Retardants*
Hydrocarbons, Brominated*

Substances

Hydrocarbons, Brominated
Flame Retardants