ABSTRACT: Biphenyl dioxygenase (BPDO) catalyzes the aerobic transformation of biphenyl and various polychlorinated biphenyls (PCBs). In three different assays, BPDO(B356) from Pandoraea pnomenusa B-356 was a more potent PCB-degrading enzyme than BPDO(LB400) from Burkholderia xenovorans LB400 (75% amino acid sequence identity), transforming nine congeners in the following order of preference: 2,3',4-trichloro approximately 2,3,4'-trichloro > 3,3'-dichloro > 2,4,4'-trichloro > 4,4'-dichloro approximately 2,2'-dichloro > 2,6-dichloro > 2,2',3,3'-tetrachloro approximately 2,2',5,5'-tetrachloro. Except for 2,2',5,5'-tetrachlorobiphenyl, BPDO(B356) transformed each congener at a higher rate than BPDO(LB400). The assays used either whole cells or purified enzymes and either individual congeners or mixtures
