Molecular genetics and evolutionary relationship of PCB-degrading bacteria.

Biphenyl-utilizing soil bacteria are ubiquitously distributed in the natural environment. They cometabolize a variety of polychlorinated biphenyl (PCB) congeners to chlorobenzoic acids through a 2,3-dioxygenase pathway, or alternatively through a 3,4-dioxygenase system. The bph genes coding for the metabolism of biphenyl have been cloned from several pseudomonads. The biochemistry and molecular genetics of PCB degradation are reviewed and discussed from the viewpoint of an evolutionary relationship.