Degradation of Aroclor 1221 and survival of strains in soil microcosms

Three bacterial strains able to use different aromatic compounds as the sole carbon and energy source were tested for their potential to degrade Aroclor 1221 in soil microcosms when present in mixed culture. Disappearance of polychlorinated biphenyls (PCBs), occurrence of metabolites, release of chloride, and survival of the laboratory-selected strains were investigated under different conditions. In principle, complete mineralization of various congeners of Aroclor 1221, a technical mixture of PCBs, by the mixed culture was possible. The autochthonous microflora negatively affected the degradation due to formation of a toxic compound from 4-chlorobenzoate. 4-Chlorobenzoate was produced by one of the added strains, Pseudomonas sp. JHK, during degradation of 4-chlorobiphenyl. The unknown metabolite of 4-chlorobenzoate led to a rapid decrease in viable counts of the laboratory-selected strains in the soil microcosm.Correspondence to: J. Havel