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

本研究对多氯联苯降解酶的结构进行了分析，并对其反应机理进行了探讨。选择联苯双加氧酶（BphA）和2，3-二羟基联苯双加氧酶（BphC）用于这些实验。将两个苯降解基因组合构建了嵌合基因，得到的嵌合酶的底物特异性差异与酶的氨基酸组成有关。为了构建基因工程微生物，我们将PCB降解基因导入土壤细菌中。结合物具有降解联苯的活性，且这种降解能力是由联苯诱导的。用紫外光（UV）照射PCB溶液，用GC-MS分析PCB溶液的脱氯情况。将UV处理的PCB溶液用于生物处理，这些结合物可以完全降解PCB。结果表明，降解酶的氨基酸差异对底物专一性的影响较小，紫外光处理有利于PCBs的完全降解。

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.