Development of the method for polychlorinated biphenyl treatment by the combination of physicochemical and biological degradation

在本研究项目中，我们分析了多氯联苯降解酶的结构，并对其反应机理进行了探讨。实验选用了联苯双加氧酶(BPhA)和2，3-二羟基联苯双加氧酶(BPHC)。苯降解基因与嵌合酶的结合构建了嵌合基因，表明酶的氨基酸差异是底物专一性差异的原因。我们还可以创造出对底物具有不同专一性的突变酶。为了构建基因操作的微生物，我们将多氯联苯降解基因引入土壤细菌。利用紫外光(UV)照射处理多氯联苯溶液，用气相色谱-质谱仪(GC-MS)分析多氯联苯的脱氯过程，利用UV处理的多氯联苯溶液进行生物处理，结果表明，降解酶的氨基酸差异对底物专一性影响很小，紫外光处理对多氯联苯的完全降解是非常有效的。

In this research project, we analyzed the structure of PCB degradation enzymes and discussed about their reaction mechanism. The biphenyl dioxygenase (BphA) and 2,3-dihydroxybiphenyl dioxygenase (BphC) were selected for these experiments. Chimeric genes were constructed with the combination between benzene degradation genes and the resulted chimeric enzymes suggested that the amino acid differences of enzymes responsible for the differences of substrate specificity. We could also create the mutated enzymes that had different specificity for substrates.To construct a genetically manipulated microorganism, we had introduced the PCB degradation genes to soil bacteria. The conjugants showed biphenyl degradation activity and this ability was inducible by biphenyl.The PCB solution was treated by ultraviolet (UV) irradiation and the dechlorination of PCBs was analyzed by GC-MS.The UV-treated PCB solution was used for the biological treatment and the PCBs were completely degraded by these combination.From our experiments, we concluded that few amino acid differences of degradation enzymes effect to the substrate specificity and the UV-treatment is very useful for the complete degradation of PCBs.