Division of Environmental Science and Engineering, National University of Singapore, Singapore, Republic of Singapore 117576.
Appl Environ Microbiol. 2010 Feb;76(3):794-802. doi: 10.1128/AEM.01872-09. Epub 2009 Dec 11.
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.
多溴二苯醚（PBDEs）因其对动物的不良影响及其在各种环境介质和生物群中的浓度不断增加而受到关注。为了深入了解 PBDEs 的命运，用来自 28 个地点的土壤和沉积物建立微宇宙，以确定它们用由六溴至九溴二苯醚组成的八溴二苯醚（octa-BDE）混合物的脱溴潜力。当用三氯乙烯（TCE）溶解的 octa-BDE 对含有来自 28 个地点中的 20 个地点的样品的微宇宙进行冲击时，以及当用正十一烷溶解的 octa-BDE 对含有来自 28 个地点中的 11 个地点的样品的微宇宙进行冲击时，脱溴作用发生了。在 2 个月内生成了从六溴至单溴二苯醚的脱溴产物。值得注意的是，有毒的四溴二苯醚占总产物的 50％。在添加八溴二苯醚混合物和正十一烷（含有 45 nM 九溴二苯醚，181 nM octa-BDEs，294 nM 七溴二苯醚和 19 nM 六溴二苯醚）的无沉积物培养物 C-N-7*中，母体化合物发生了广泛的脱溴作用，生成了六溴二苯醚（56 nM），五溴二苯醚（124 nM）和四溴二苯醚（150 nM），在 42 天内可能通过代谢过程。基于 16S rRNA 基因的分析表明，在 14 个活跃的微宇宙中有 11 个存在 Dehalococcoides 种。但是，在一些微宇宙中，未知的脱溴物种在没有其他添加的卤代电子受体（例如 TCE）的情况下脱溴八溴二苯醚混合物。这些发现为评估微生物对较高溴化 PBDEs 的还原脱溴作用以形成较少溴化的同系物提供了信息，这是环境中检测到的更有毒同系物（例如五溴和四溴二苯醚）的可能来源。
