Aerobic Biotransformation of Polybrominated Diphenyl Ethers (PBDEs) by Bacterial Isolates

Abstract

Polybrominated diphenyl ethers (PBDEs) are flame retardants that have been used in consumer products and furniture for three decades. Currently, very little is known about their fate in the environment and specifically about their susceptibility to aerobic biotransformation. Here, we investigated the ability of the polychlorinated biphenyl (PCB) degrading bacteria Rhodococcus jostii RHA1 and Burkholderia xenovorans LB400 to transform mono- through hexa-BDEs at ppb levels. We also tested the PBDE transforming abilities of related strain Rhodococcus sp. RR1 and the ether-degrading Pseudonocardia dioxanivorans CB1190. The two PCB-degrading strains transformed all of the mono- through penta-BDEs and strain LB400 transformed one of the hexa-BDEs. The extent of transformation was inversely proportional to the degree of bromination. Strains RR1 and CB1190 were only able to transform the less brominated mono- and di- BDE congeners. RHA1 released stoichiometric quantities of bromide while transforming mono- and tetra-BDE congeners. LB400 instead converted most of a mono-BDE to a hydroxylated mono-BDE. This is the first report of aerobic transformation of tetra-, penta- and hexa-BDEs as well as the first report of stoichiometric release of bromide during PBDE transformation.

Aerobic biotransformation of decabromodiphenyl ether (PBDE-209) by Pseudomonas aeruginosa

“…It was reported that strain RHA1 was able to release large amounts of bromide ions during the transformation of tetrabromodiphenyl ether (PBDE-47) (Robrock et al, 2009). And strain DB-1 debrominated part of PBDE-209 at aerobic incubation using lactate as carbon source (Deng et al, 2011).…”

“…PH-07 could aerobically break down a number of lower-bromodiphenyl ethers congeners, such as mono-, di-, and tribromodiphenyl ethers. In recent years, Robrock et al (2008Robrock et al ( , 2009) investigated four strains which could transform mono-through hexabromodiphenyl ethers at ppb level. In these studies, two PCB-degrading strains, Rhodococcus jostii RHA1 and Burkholderia xenovorans LB400 transformed all of the mono-and pentabromodiphenyl ethers and strain LB400 transformed one of the hexabromodiphenyl ethers, while Rhodococcus sp.…”

Aerobic Degradation of 4-Monobrominated Diphenyl Ether: Identifying and Characterizing Three Strains Isolated from Populus tomentosa Phyllosphere

“…For example, Rhodococcus sp. RR1 could aerobically transform 20% of 17 ug L -1 mono-and di-BDE within three days [23]. Sphingomonas sp.…”

“…Microbial anaerobic transformation has demonstrated that, in most cases, PBDEs were debrominated to less brominated congeners, but required a relatively long time [11,22]. Compared to anaerobic degradation, the advantages of microbial aerobic degradation on PBDEs are obvious: the degradation time cycle is shorter and the metabolites will not carry greater toxicity as the result of the characteristic degradation mechanism that PBDEs go through for hydroxylation and ring opening reaction [23][24].…”

Microbial community shift with decabromodiphenyl ether (BDE 209) in sediments of the Pearl River estuary, China

“…Three PBDE technical mixtures [pentabromodiphenyl ether,octabromodiphenyl ether and decabromodiphenyl ether (BDE 209)] were widely integrated into products. As of 2006, the penta-and octa-bromodiphenyl ether technical mixtures have been banned and removed from production (Robrock et al 2009). However, BDE 209 remains legal in most countries and continues to be heavily used (He et al 2006).…”