METABOLISM OF HYDROXYBIPHENYL AND CHLORO-HYDROXYBIPHENYL BY BIPHENYL/CHLOROBIPHENYL DEGRADING PSEUDOMONAS-TESTOSTERONI, STRAIN B-356

A biphenyl (BP) and chlorobiphenyl (CBP) metabolizing Pseudomonas testosteroni, strain B-356 was also capable of utilizing 2-,3-, and 4-hydroxybiphenyl. Data presented here suggest that utilization of biphenyl and mono-substituted biphenyls involves the enzymes of the same pathway. Chloro-hydroxybiphenyls were also metabolized by strain B-356. The unsubstituted ring is first hydroxylated in position 2 and 3 and then cleaved in a meta 1, and 2, position to ultimately generate the benzoic acid derivatives. Since strain B-356 was capable of utilizing benzoic acid and mono-hydroxybenzoic acids, the utilization of biphenyl, 2-,3-, and 4-hydroxybiphenyl is complete at non-toxic concentrations of the substrates. Chlorobenzoic acids and chloro-hydroxybenzoic acids were not metabolized further by this strain. Studies using Pseudomonas putida, strain KT2440 carrying cloned BP/CBP genes from strain B-356 provided further evidence for the presence of a common pathway for the metabolism of the above compounds in P. testosteroni, strain B-356. Suggestions are made on significance of the broad substrate specificity of the enzymes of biphenyl/chlorobiphenyl pathway in regard to their possible origin and in relation to PCB mixture degradation.