School of Environmental Engineering, Henan University of Technology, Zhengzhou, No. 100 Lianhua Street, High-tech Industrial Development District, Zhengzhou, 450001, Henan, China.
College of informatics, Huazhong Agricultural University, Wuhan, 430070, China.
Environ Sci Pollut Res Int. 2023 Aug;30(36):85558-85568. doi: 10.1007/s11356-023-28505-w. Epub 2023 Jun 30.
A bacterial strain Citrobacter sp. HJS-1 was discovered from the sludge in a drainage canal of a coal mine. Firstly, its biodegradation capacity for benzo[a]pyrene (BaP) was detected under different concentrations. The results proved that the strain possessed excellent biodegradation capacity for BaP with high-efficiency degradation rates ranging from 78.9 to 86.8%. The highest degradation rate was observed in the low-concentration sample, and the high-concentration BaP had a slight influence on the biodegradation capacity due to the potential toxicity of BaP and its oxygen-containing derivatives. Meanwhile, the degradation test for the other five aromatic hydrocarbons (2- to 4-ring) proved that the strain had a comprehensive degradation potential. To clarify the biodegradation mechanism of BaP, a dioxygenase structure was constructed by homology modeling. Then, the interactions between dioxygenase and BaP were researched by molecular simulation. Combined with the identification of the vital BaP-cis-7,8-dihydrodiol intermediate and the interaction analysis, the initial oxidation mode and the binding site of BaP were revealed in the dioxygenase. Taken together, this study has offered a way to understand the biodegradation process of BaP and its interaction mechanism based on experimental and theoretical analysis.
一株从煤矿排水沟污泥中分离得到的柠檬酸杆菌（Citrobacter sp.）HJS-1，首先在不同浓度下检测了其对苯并[a]芘（BaP）的生物降解能力。结果表明，该菌株对 BaP 具有较高的生物降解能力，高效降解率范围为 78.9%至 86.8%。在低浓度样品中观察到最高的降解率，而高浓度 BaP 对生物降解能力的影响较小，这是由于 BaP 及其含氧衍生物的潜在毒性。同时，对其他五种芳烃（2-4 环）的降解测试证明了该菌株具有综合的降解潜力。为了阐明 BaP 的生物降解机制，通过同源建模构建了一种双加氧酶结构。然后，通过分子模拟研究了双加氧酶与 BaP 的相互作用。结合关键 BaP-顺-7,8-二氢二醇中间产物的鉴定和相互作用分析，揭示了双加氧酶中 BaP 的初始氧化模式和结合位点。综上所述，该研究通过实验和理论分析，为理解 BaP 的生物降解过程及其相互作用机制提供了一种方法。
