Abstract
Numerous experiments have been conducted to determine the nature of diverse microbial transformations of PCBs. The optimal process should mineralize the compounds to carbon dioxide, water, and chlorine, but for this to occur, Cl must be removed from the biphenyl ring and resultant intermediates must be cleaved and oxidized. Various laboratory and field studies are described that have investigated anaerobic PCB biotransformations and aerobic catabolism. Results are presented from a program to selectively obtain additional bacterial isolates that might contain elements both of anaerobic and aerobic PCB dissimilatory pathways, using Aroclor 1242. From a five-membered bacterial consortium obtained from sewage sludge, Comamonas testosteroni was isolated. Metabolism of biphenyl by C. testosteroni resulted in the formation of several metabolites. The production of chlorinated benzoic acids indicated metabolic attack on the less- chlorinated ring. Good results were also found with Rhodococcus rhodochrous and Pseudomonas putida.