Compound degraded:Hepta-brominated diphenyl ethers BDEs (BDE-183, 184, 191)

General Description (About POP compound)

Hepta- brominated diphenyl ethers belongs to a wider group of polybrominated diphenyl ethers (PBDEs), a class of organobromine compounds that are used as flame retardants. Hepta- 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

Publications

Abstract Title Authors Article Link
Polybrominated diphenyl ethers (PBDEs) are emerging persistent organic pollutants and have consequently drawn much environmental concern. The objective of this study was to evaluate reductive debromination of decabromodiphenyl ether (BDE-209) by anaerobic microbes from river sediment under various conditions. The debromination rates for BDE-209 were enhanced by the addition of brij 30, brij 35, rhamnolipid, surfactin, vitamin B12, zero-valent iron, acetate, lactate, and pyruvate. Zero-valent iron yielded the highest BDE-209 debromination. For the various PBDE congeners, the high-to-low order of debromination rates in sediment was BDE-209 > BDE-99 > BDE-47 > BDE-28 > BDE-15. The intermediate products resulting from the reductive debromination of BDE-209 in sediment were nona-BDE (BDE-207), octa-BDEs (BDE-196, 197), hepta-BDEs (BDE-183, 184, 191), hexa-BDEs (BDE-138, 154), penta-BDEs (BDE-85, 99, 100, 119), tetra-BDEs (BDE-47, 49, 66, 71), tri-BDEs (BDE-17, 28), di-BDEs (BDE-7, 15), and mono-BDE (BDE-3). Our result shows BDE-209 can be debrominated successively to BDE-3 by anaerobic microbes from river sediment. This research offers feasible methods for removal of BDE-209 in river sediment for bioremediation. Reductive debromination of decabromodiphenyl ether by anaerobic microbes from river sediment Huang et al., 2014 Link
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 the 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 Polybrominated Diphenyl Ethers (PBDEs) by Bacterial Isolates Robrock et al., 2009 Link
Polybrominated diphenyl ethers (PBDEs) have attracted attention recently due to their proven adverse effects on animals and their increasing concentrations in various environmental media and biota. To gain insight into the fate of PBDEs, microcosms established with soils and sediments from 28 locations were investigated to determine their debromination potential with an octa-brominated diphenyl ether (octa-BDE) mixture consisting of hexa- to nona-BDEs. Debromination occurred in microcosms containing samples from 20 of the 28 locations when they were spiked with octa-BDE dissolved in the solvent trichloroethene (TCE), which is a potential cosubstrate for stimulating PBDE debromination, and in microcosms containing samples from 11 of the 28 locations when they were spiked with octa-BDE dissolved in nonane. Debromination products ranging from hexa- to mono-BDEs were generated within 2 months. Notably, the toxic tetra-BDEs accounted for 50% of the total product. In sediment-free culture C-N-7* amended with the octa-BDE mixture and nonane (containing 45 nM nona-BDE, 181 nM octa-BDEs, 294 nM hepta-BDE, and 19 nM hexa-BDE) there was extensive debromination of the parent compounds, which produced hexa-BDE (56 nM), penta-BDEs (124 nM), and tetra-BDEs (150 nM) within 42 days, possibly by a metabolic process. A 16S rRNA gene-based analysis revealed that Dehalococcoides species were present in 11 of 14 active microcosms. However, unknown debrominating species in some of the microcosms debrominated the octa-BDE mixture in the absence of other added halogenated electron acceptors (such as TCE). These findings provide information that is useful for assessing microbial reductive debromination of higher brominated PBDEs to less-brominated congeners, a possible source of the more toxic congeners (e.g., penta- and tetra-BDEs) detected in the environment. Reductive Debromination of Polybrominated Diphenyl Ethers by Anaerobic Bacteria from Soils and Sediments Lee and He. 2010 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
Aerobic biodegradation of 2,2?,4,4?-tetrabrominated diphenyl ether (BDE-47) by Phanerochaete chrysosporium in the presence of Cd2+ was investigated in this study. The results showed that P. chrysosporium could effectively degrade BDE-47, and its extracellular enzyme played an important role in the process of decomposition. BDE-47 biodegradation by fungi was more tolerant than extracellular enzyme in the presence of Cd2+. Also, both of the activity of two typical enzymes, MnP and LiP, descended with ascended Cd2+ concentration. Based on the four mono-hydroxylated PBDEs (5-OH-BDE-47, 4?-OH-BDE-17, 6-OH-BDE-47, and 2?-OH-BDE-28) and two bromophenols (2,4-DBP, 4-BP) detected, three possible degradation pathways were proposed, inferring that BDE-47 was more easily to transform via hydroxylation. With addition of Cd2+, the types of degradation products did not change, merely a variation of the content of these products observed. Meanwhile, the major metabolites of BDE-47, bromophenol compounds, have been found to be transformed or even mineralized by P. chrysosporium quickly, which also helped better explain why the amounts of BDE-47 decomposed did not match with that of the metabolites detected. Biodegradation of 2,2?,4,4?-tetrabromodiphenyl ether (BDE-47) by Phanerochaete chrysosporium in the presence of Cd2+ Cao et al., 2017 Link
In this study, an aerobic strain identified as Rhodococcus sp. was isolated from the sediment of a typical electronic waste disassemble site, Taizhou, China. This strain could use BDE-209 as the sole carbon and energy source and degrade 65.1 % of BDE-209 (initial concentration being 50 mg/L) within 144 h. To explore the BDE-209 degradation properties of this strain with the co-existed electronic donor, zerovalent iron/activated carbon (ZVI/AC) was introduced to build a microbial-chemical coupling system, which was found to promote the degradation of BDE-209 slightly (74.7 % in 144 h). Moreover, the debromination products in both of the batch experiments were determined with GC/MS, which showed that lower brominated PBDE congeners were produced almost in order of the number of bromine ions, ranged from nona- to di-BDEs. In addition, the possible debromination pathways of BDE-209 for each system were proposed respectively, which confirmed the microbial activity of BDE-209 debromination. Since some of the lower-brominated BDE congeners are much toxic than BDE-209, these microbial activities might bring potential hazards to the environment with BDE-209 contamination. It is the first time to investigate the transformation of BDE-209 with microbial-chemical coupling system, which is universal in the nature, thus suggesting that the ecological safety of environment exposed to PBDEs should be focused in the future. Aerobic debromination of BDE-209 by Rhodococcus sp. coupled with zerovalent iron/activated carbon Liu et a., 2015 Link
A metal resistant bacterial strain, Bacillus cereus JP12, could use decabromodiphenyl ether (BDE-209) as the sole carbon and energy source for growth in mineral salt medium. Under the conditions of pH 6.0, 30 °C, 150 rpm and an inoculum of OD600 = 0.6, more than 88% of the initial BDE-209 (1 mg/L) was degraded after 12 days. The addition of appropriate surfactants and additional carbon sources could enhance the biodegradation efficiency of BDE-209. The presence of Cu2+ (?8 mg/L) and Zn2+ (?15 mg/L) provided a slight stimulating effect on BDE-209 removal. However, BDE-209 biodegradation efficiency was decreased when adding higher levels of metals due to reduced substrate availability caused by excess metal adsorption into the cell surface. Biosorption of heavy metals by JP12 led to release of light metals such as K+ and Na+. A BDE-209 biodegradation pathway was proposed on the basis of metabolite identification. Biodegradation of decabromodiphenyl ether (BDE-209) by a metal resistant strain, Bacillus cereus JP12 Lu et al., 2013 Link