Characterization of the Phenol Hydroxylase from Burkholderia kururiensis KP23 Involved in Trichloroethylene Degradation by Gene Cloning and Disruption

抄録

Burkholderia kururiensis KP23 was isolated as a trichloroethylene (TCE)-degrading bacterium. Its degrading activity was induced by phenol, suggesting that the degradation is catalyzed by a phenol hydroxylase (PH). To elucidate the involvement of the PH in the degradation of TCE, the gene cluster for the enzyme was cloned and sequenced. The structural genes (phkABCDEFG) and cognate regulatory gene (phkR) were identified in a divergent transcriptional organization. The products are homologous to those of dmpRKLMNOPQ of Pseudomonas putida CF600, sharing 30-62% identity of amino acid sequence, indicating that the PH is a multi-component enzyme. Disruption of phkD encoding a large oxygenase subunit of the enzyme completely abolished the utilization of phenol as well as degradation of TCE by strain KP23. In addition, a disruptant of phkR was not able to grow on phenol and showed no activity to degrade TCE, indicating that PhkR is an activator and controls the expression of phkABCDEFG.