Investigation into PCB biodegradation using uniformly C-14-labelled dichlorobiphenyl

Biodegradation of polychlorinated biphenyls (PCBs) in soil is considered to be very complex due to various physico-chemical factors involved. Isotope labelling technique is the best to trace fate of the xenobiotic in the envi ronment. In this work, the uniformly C-14-labelled PCB congener 11(3,3'-chl orobiphenyl) was chosen as a low chlorinated coplanar biphenyl which was as sumed to be readily degraded by microorganisms. Pleurotus ostreatus and two Pseudomonas species, representing white rot fungi and soil bacteria were u sed separately or in a consortium. The amount of liberated (CO2)-C-14 and r adio-HPLC, HPLC, GC-MS, and radio-TLC analyses of extracts at the end of a two-month experiment showed that the mineralization of PCB 11 was < 0.4%, v olalilization < 3.1%, and 30% of radioactivity was irreversibly bound to th e soil matrix. The respective contents of all intermediate metabolites were 4.7 to 10.5 and 2.5 to 2.7% where Pseudomonas alcaligenes alone or in comb ination with P. putida was applied. 3-Chlorobenzoic acid was the major biod egradation product.