State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China.
State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China.
J Hazard Mater. 2019 Dec 15;380:120833. doi: 10.1016/j.jhazmat.2019.120833. Epub 2019 Jun 29.
Hexabromocyclododecanes (HBCDs) are the second-most widely used brominated flame retardants. They cause inappropriate antidiuretic hormone syndrome and can induce cancer. However, little information is available about bacterial degradation of HBCDs. In this study, HBCDs (α-, β- and γ-HBCD) degrading strain Pseudomonas aeruginosa HS9 was isolated, identified, and characterized. The strain HS9 could remove 69% (± 0.05%) of 1.7 mg/L HBCDs in 14 days. Based on identification of metabolites, this bacterium could oxidize HBCDs by two pathways. In the first, HBCDs are sequentially debromized to tetrabromocyclododecene, dibromocyclododecadiene, and then debromized once more to cis, trans, trans-1, 5, 9-cyclododecatriene (CDT). After that, CDT is then oxidized to 1,2-epoxy-5,9-cyclododecadiene. The second identified pathway is a simultaneous debrominating and hydroxylating process based on the detection of 2,5,6,9,10-pentabromocyclododecanols, which were newly identified. The strain's effects on plant-maize growth were tested and bioremediation evaluation trials were performed. The addition of strain HS9 could decrease HBCDs of 4.08 mg/g (87.6% removed) and 0.1 mg/g (25% removed) in soil and plants, respectively. Microbial diversity analysis shows that the addition of strain HS9 can promote the abundance of plant-beneficial bacteria, such as Methylobacillus, Nitrosomonas, Plancoccus, Bacillus, and Rhodococcus. The results provide insights for the bioremediation of HBCDs-contaminated soils.
六溴环十二烷（HBCDs）是使用最广泛的溴系阻燃剂之一。它们会引起不适当的抗利尿激素综合征，并可能诱发癌症。然而，关于 HBCDs 的细菌降解的信息很少。在本研究中，分离、鉴定并表征了能够降解 HBCDs 的铜绿假单胞菌（Pseudomonas aeruginosa）HS9 菌株。该菌株 HS9 在 14 天内可以去除 1.7mg/L HBCDs 中的 69%（±0.05%）。基于代谢物的鉴定，该细菌可以通过两条途径氧化 HBCDs。在第一种途径中，HBCDs 依次脱溴生成四溴环十二烯、二溴环十二二烯，然后再次脱溴生成顺式、反式、反式-1,5,9-环十二碳三烯（CDT）。之后，CDT 被氧化为 1,2-环氧-5,9-环十二二烯。第二种鉴定的途径是基于新鉴定的 2,5,6,9,10-五溴环十二烷醇的检测，该途径是同时脱溴和羟基化的过程。还测试了该菌株对植物-玉米生长的影响，并进行了生物修复评价试验。添加 HS9 菌株可以分别降低土壤和植物中 4.08mg/g（去除 87.6%）和 0.1mg/g（去除 25%）的 HBCDs。微生物多样性分析表明，添加 HS9 菌株可以促进植物有益细菌如甲基杆菌、亚硝化单胞菌、Planococcus、芽孢杆菌和红球菌的丰度。这些结果为 HBCDs 污染土壤的生物修复提供了思路。
