ANAEROBIC BIODEGRADATION OF PENTACHLOROPHENOL IN A CONTAMINATED SOIL INOCULATED WITH A METHANOGENIC CONSORTIUM OR WITH DESULFITOBACTERIUM-FRAPPIERI STRAIN PCP-1

Anaerobic biodegradation of pentachlorophenol (PCP) in a contaminated soil from a wood-treating industrial site was studied in soil slurry m icrocosms inoculated with a PCP-degrading methanogenic consortium. Whe n the microcosms containing 10%-40% (w/v) soil were inoculated with th e consortium, more than 90% of the PCP was removed in less than 30 day s at 29 degrees C. Less-chlorinated phenols, mainly 3-chlorophenol wer e slowly degraded and accumulated in the cultures. Addition of glucose and sodium formate to the microcosms was not necessary, suggesting th at the organic compounds in the soil can sustain the dechlorinating ac tivity. Inoculation of Desulfitobacterium frappieri strain PCP-1 along with a 3-chlorophenol-degrading consortium in the microcosms also res ulted in the rapid dechlorination of PCP and the slow degradation of 3 -chlorophenol. Competitive polymerase chain reaction experiments showe d that PCP-1 was present at the same level throughout the 21-day biotr eatment. D. frappieri, strain PCP-1, inoculated into the soil microcos ms, was able to remove PCP from soil containing up to 200 mg PCP/kg so il. However, reinoculation of the strain was necessary to achieve more than 95% PCP removal with a concentration of 300 mg and 500 mg PCP/kg soil. These results demonstrate that D. frappieri strain PCP-1 can be used effectively to dechlorinate PCP to 3-chlorophenol in contaminate d soils.