Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan.
Chemosphere. 2013 Aug;92(10):1343-8. doi: 10.1016/j.chemosphere.2013.05.051. Epub 2013 Jun 12.
Tetrabromobisphenol A (TBBPA) is the most widely used brominated flame retardant on the market. It has been detected in various environmental samples, and a growing body of evidence has demonstrated its toxic effects on living organisms. In this study, we report the enrichment and phylogenetic identification of bacteria that debrominate TBBPA to bisphenol A in the presence of humin. Incubation experiments indicated that humin was required for this debromination activity. Of the five compounds examined for inclusion in the TBBPA-debrominating culture, formate was the optimal electron donor. A 16S rRNA gene library showed that the culture was dominated by three known dehalogenator genera: Dehalobacter, Geobacter, and Sulfurospirillum. Further investigation indicated that Dehalobacter was responsible for the debromination of TBBPA. PCR-denaturing gradient gel electrophoresis analysis showed that Dehalobacter grew in the culture by utilizing TBBPA. Moreover, the copy number of the Dehalobacter 16S rRNA genes increased by about two orders of magnitude in the cultures without the addition of TBBPA, whereas it increased by approximately four orders of magnitude when TBBPA was present. The incubation experiments showed that Dehalobacter was reliant on humin for its debromination activity, indicating a new type of metabolism in Dehalobacter that is linked to humin respiration.
四溴双酚 A（TBBPA）是市场上应用最广泛的溴化阻燃剂。它已在各种环境样本中被检测到，越来越多的证据表明它对生物体具有毒性作用。在这项研究中，我们报告了在腐殖质存在下能够将 TBBPA 脱溴化为双酚 A 的细菌的富集和系统发育鉴定。孵育实验表明，这种脱溴活性需要腐殖质。在五种被检测到的可用于 TBBPA 脱溴培养的化合物中，甲酸盐是最佳的电子供体。16S rRNA 基因文库显示，该培养物主要由三种已知的脱卤属：脱硫弧菌属、地杆菌属和硫螺旋菌属组成。进一步的研究表明，脱硫弧菌负责 TBBPA 的脱溴作用。PCR-变性梯度凝胶电泳分析表明，脱硫弧菌通过利用 TBBPA 在培养物中生长。此外，在没有添加 TBBPA 的培养物中，Dehalobacter 16S rRNA 基因的拷贝数增加了约两个数量级，而当存在 TBBPA 时，其拷贝数增加了约四个数量级。孵育实验表明，脱硫弧菌依赖腐殖质进行脱溴活性，这表明脱硫弧菌存在一种与腐殖质呼吸有关的新型代谢方式。
