A META CLEAVAGE PATHWAY FOR 4-CHLOROBENZOATE, AN INTERMEDIATE IN THE METABOLISM OF 4-CHLOROBIPHENYL BY PSEUDOMONAS-CEPACIA P166

Bacterial degradation of biphenyl and polychlorinated biphenyls procee ds by a well-studied pathway which produces benzoate and 2-hydroxypent -2,4-dienoate (or, in the case of polychlorinated biphenyls, the chlor inated derivatives of these compounds). Pseudomonas cepacia P166 utili zes 4-chlorobiphenyl for growth and produces 4-chlorobenzoate as a cen tral intermediate. In this study we found that strain P166 further tra nsforms 4-chlorobenzoate to 4-chlorocatechol, which is mineralized by a meta cleavage pathway. Key metabolites which we identified include t he meta cleavage product (5-chloro-2-hydroxymuconic semialdehyde), 5-c hloro-2-hydroxymuconate, 5-chloro-2-oxopent-4-enoate, 5-chloro-4-hydro xy-2-oxopentanoate, and chloroacetate. Chloroacetate accumulated trans iently, and slow but stoichiometric dehalogenation was observed.