Study on biodegradation of PCBs by white-rot fungi.

The biodegradation of Delor 103, a commercial mixture of PCB congeners, was studied with eight strains of white rot fungi in two nutritive media: in mineral nitrogen limited medium (so called Kirk medium) and in complex Malt- extract glucose medium. The most efficient biodegradation was observed with the fungus Pleurotus ostreatus, where 99% of PCB congener sum was degraded after 42 days in both media. Bjerkandera adusta was able to degrade 89% of PCB congener sum within 42 days in complex medium. Irpex lacteus removed 70% of PCB congener sum within 42 days in Kirk medium. Other white rot fungi showed lower biodegradation ability, degrading only low chlorinated biphenyls. Further, urgent toxicity of samples was monitored during the Delor 103 biodegradation. P. ostreatus proved to be the most suitable agens for PCB decontamination as a significant reduction of toxicity in comparison with controls was observed during the PCB degradation. In case of other fungi, no reduction of urgent toxicity was observed showing a disadvantage of their use for PCB biodegradation. Activities of ligninolitic enzymes during biodegradation were also studied. In both media laccase activity was detected in Dichomitus squalens, Pycnoporus cinnabarinus and Trametes versicolor cultures. Ligninperoxidase enzyme activity was..