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

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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.