COMPARISON OF GAS-CHROMATOGRAPHY AND MINERALIZATION EXPERIMENTS FOR MEASURING LOSS OF SELECTED POLYCHLORINATED BIPHENYL CONGENERS IN CULTURES OF WHITE-ROT FUNGI

Two methods were used to compare the biodegradation of six polychlorin ated biphenyl (PCB) congeners by 12 white rot fungi. Pear fungi were f ound to be more active than Phanerochaete chrysosporium ATCC 24725. Bi odegradation of the following congeners was monitored by gas chromatog raphy: 2,3-dichlorolbiphenyl, 4,4'-dichlorobiphenyl 2,4',5-trichlorobi phenyl (2,4',5-TCB), 2,2',4,4'-tetrachlorobiphenyl, 2,2',5,5'-tetrachl orobiphenyl, and 2,2',4,4',5,5'-hexachlorobiphenyl. The congener teste d for mineralization was 2,4',5-[U-C-14]TCB. Culture supernatants were also assayed for lignin peroxidase and manganese peroxidase activitie s. Of the fungi tested, two strains of Bjerkandera adusta (UAMH 8258 a nd UAMH 7308), one strain of Pleurotus ostreatus (UAMH 7964), and Tram etes versicolor UAMH 8272 gave the highest biodegradation and minerali zation. P. chrysosporium ATCC 24725, a strain frequently used in studi es of PCB degradation, gave the lowest mineralization and biodegradati on activities of the 12 fungi reported here, Low but detectable levels of lignin peroxidase and manganese peroxidase activity were present i n culture supernatants, but no correlation was observed among any comb ination of PCB congener biodegradation, mineralization, and lignin per oxidase or manganese peroxidase activity. With the exception of P. chr ysosporium, congener loss ranged from 40 to 96%; however, these values varied due to nonspecific congener binding to fungal biomass and glas sware. Mineralization was much lower, less than or equal to 11%, becau se it measures a complete oxidation of at least part of the congener m olecule but the results were more consistent and therefore more reliab le in assessment of PCB biodegradation.