Compound degraded:Penta-brominated diphenyl ethers
General Description (About POP compound)
Penta-brominated diphenyl ethers belongs to a wider group of polybrominated diphenyl ethers (PBDEs), a class of organobromine compounds that are used as flame retardants. Penta-brominated diphenyl ethers have been used in a wide array of products, including building materials, electronics, furnishings, motor vehicles, airplanes, plastics, polyurethane foams,[1] and textiles. They are structurally akin to polychlorinated diphenyl ethers (PCDEs), polychlorinated biphenyls (PCBs) and other polyhalogenated compounds, consisting of two halogenated aromatic rings.
Biodegradation pathway
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Publications
| Abstract | Title | Authors | Article Link |
|---|---|---|---|
| Polybrominated diphenyl ethers (PBDEs) are a class of environmental pollutants that have been classified as persistent organic pollutants since 2009. In this study, a sediment-free enrichment culture (culture G) was found to reductively debrominate octa- and penta-BDE technical mixtures to less-brominated congeners (tetra-, tri-, and di-BDEs) via a para-dominant debromination pattern for the former and a strict para debromination pattern for the latter. Culture G could debrominate 96% of 280 nM PBDEs in an octa-BDE mixture to primarily tetra-BDEs in 21 weeks. Continuous transferring of culture G with octa-/penta-BDEs dissolved in n-nonane or trichloroethene (TCE) yielded two strains (Acetobacterium sp. strain AG and Dehalococcoides sp. strain DG) that retained debromination capabilities. In the presence of lactate but without TCE, strain AG could cometabolically debrominate 75% of 275 nM PBDEs in a penta-BDE mixture in 33 days. Strain AG shows 99% identity to its closest relative, Acetobacterium malicum. In contrast to strain AG, strain DG debrominated PBDEs only in the presence of TCE. In addition, 18 out of 19 unknown PBDE debromination products were successfully identified from octa- and penta-BDE mixtures and revealed, for the first time, a comprehensive microbial PBDE debromination pathway. As an acetogenic autotroph that rapidly debrominates octa- and penta-BDE technical mixtures, Acetobacterium sp. strain AG adds to the still-limited understanding of PBDE debromination by microorganisms. | Isolation of Acetobacterium sp. Strain AG, Which Reductively Debrominates Octa- and Pentabrominated Diphenyl Ether Technical Mixtures | Ding et al., 2013 | Link |
| Polybrominated diphenyl ethers (PBDEs) are a class of widely used flame retardants that have recently been detected in environmental samples, diverse biota, human blood serum, and breast milk at exponentially increasing concentrations. Currently, little is known about the fate of these compounds, and in particular, about the microbial potential to degrade them. In this study, debromination of deca-BDE and an octa-BDE mixture is demonstrated with anaerobic bacteria including Sulfurospirillum multivorans and Dehalococcoides species. Hepta- and octa-BDEs were produced by the S.multivorans culture when it was exposed to deca-BDE, although no debromination was observed with the octa-BDE mixture. In contrast, a variety of hepta- through di-BDEs were produced by Dehalococ coides-containing cultures exposed to an octa-BDE mixture, despite the fact that none of these cultures could debrominate deca-BDE. The more toxic hexa-154, penta-99, tetra-49, and tetra-47 were identified among the debromination products. Because the penta-BDE congeners are among the most toxic PBDEs, debromination of the higher congeners to more toxic products in the environment could have profound implications for public health and for the regulation of these compounds. | Microbial Reductive Debromination of Polybrominated Diphenyl Ethers (PBDEs) | He et al., 2006 | Link |
| Polybrominated diphenyl ethers (PBDEs) are widespread global contaminants due to their extensive usage as flame retardants. Among the 209 PBDE congeners, tetra-brominated diphenyl ether (tetra-BDE) (congener 47) and penta-BDEs (congeners 99 and 100) are the most abundant, toxic, and bioaccumulative congeners in the environment. However, little is known about microorganisms that carry out debromination of these congeners under anaerobic conditions. In this study, we describe a coculture GY2 consisting of Dehalococcoides and Desulfovibrio spp., which is capable of debrominating ?1180 nM of congeners 47, 99, and 100 (88–100% removal) to the nonbrominated diphenyl ether at an average rate of 36.9, 19.8, and 21.9 nM day–1, respectively. Ortho bromines are preferentially removed during the debromination process. The growth of Dehalococcoides links tightly with PBDE debromination, with an estimated growth yield of 1.99 × 1014 cells per mole of bromide released, while the growth of Desulfovibrio could be independent of PBDEs. The growth-coupled debromination suggests that Dehalococcoides cells in the coculture GY2 are able to respire on PBDEs. Given the ubiquity and recalcitrance of the tetra- and penta-BDEs, complete debromination of these congeners to less toxic end products (e.g. diphenyl ether) is important for the restoration of PBDE-contaminated environments. | Complete Debromination of Tetra- and Penta-Brominated Diphenyl Ethers by a Coculture Consisting of Dehalococcoides and Desulfovibrio Species | Lee et al., 2011 | Link |
| Because of the bioaccumulation of penta- and tetra-polybrominated diphenyl ether (PBDE) flame retardants in biota, the environmental biotransformation of decabromodiphenyl ether (BDE-209) is of interest. BDE-209 accounts for more than 80% by mass of PBDE production and is the dominant PBDE in sediments. Most sediments are anaerobic and reports of microbial reductive dehalogenation of hydrophobic persistent organohalogen pollutants are numerous. Reductive debromination of BDE-209 in the environment could provide a significant source of lesser-brominated PBDEs to biota. Moreover, a recent study showed that BDE-209 debrominates in sewage sludge, and another demonstrated that some halorespiring bacteria will debrominate BDE-209. To determine whether reductive debromination of BDE-209 occurs in sediments, parallel experiments were conducted using anaerobic sediment microcosms and a cosolvent-enhanced biomimetic system. In the biomimetic system, reductive debromination occurred at rates corresponding to bromine substitution levels with a BDE-209 half-life of only 18 s compared with a half-life of almost 60 days for 2,2?,4,4?-tetrabromodiphenyl ether. In sediment, the measured debromination half-life of BDE-209 was well over a decade and was in good agreement with the predicted value obtained from the biomimetic experiment. Product congeners were predominantly double para-substituted. BDE-209 debrominated in sediment with a corresponding increase in nona-, octa-, hepta-, and hexa-PBDEs. Nine new PBDE congeners appeared in sediment from reductive debromination. Given the very large BDE-209 burden already in sediments globally, it is important to determine whether this transformation is a significant source of lesser-brominated PBDEs to the environment. | Reductive Debromination of Polybrominated Diphenyl Ethers in Anaerobic Sediment and a Biomimetic System | Tokarz et al., 2008 | Link |
| The degradation of flame retardant polybrominated diphenyl ethers (PBDE), including tetra-brominated diphenyl ether (BDE-47), penta-brominated diphenyl ether (BDE-99 and -100), and hexa-brominated diphenyl ether (BDE-153 and -154), by anaerobic bacterial mixed cultures isolated from river sediment was investigated. The effects of PBDEs on changes of anaerobic bacterial community in sediment culture were also studied. Sediments were collected from Er-Jen River and Nan-Kan River basins, which were both heavily polluted rivers in Taiwan, and bacteria from the sediment samples were enriched before the experiment was conducted. Into the anaerobic bacterial mixed cultures, 0.1 microg/mL of PBDEs was added followed by incubation under 30 degrees C for 70 days. Residues of PBDE were determined by gas chromatography with electron capture detector (GC-ECD), and the changes of bacterial community were analyzed by denaturing gradient gel electrophoresis (DGGE). Less than 20% of PBDEs were degraded after 70 days of incubation in all samples except for BDE-47 from the Nan-Kan River sediment. In that culture, BDE-47 was found to have notably degraded. In particular, after 42 days of incubation; BDE-47 was degraded, suddenly and sharply, to a negligible level on Day 70, and the result was confirmed by a repeated experiment. An interesting result was that although BDE-47 was degraded fast in the Nan-Kan River sediment, the bacterial communities did not shift significantly as we had speculated at Day 70. From UPGMA dendrograms, PBDEs changed the composition of bacterial communities, and the extents varied with the variety of PBDE congeners. By the amendment with BDE-153 or -154, bacterial communities would be changed immediately and irreversibly throughout the rest of the incubation period. No significant difference in degradation of PBDEs was observed between sediment bacteria from Er-Jen River and Nan-Kan River. However, the results verified the persistence of PBDEs in the environment. | Interaction of polybrominated diphenyl ethers (PBDEs) with anaerobic mixed bacterial cultures isolated from river sediment | Yen et al., 2009 | Link |