Pentachlorophenol biodegradation and detoxification by the white-rot fungus phanerochaete chrysosporium

Pentachlorophenol (PCP) was widely used as a wood preservative and pesticide for several decades. Presently it is considered an ubiquitous contaminant, so it is important to find a good strategy to reduce PCP levels in the environment. One feasible option is using the ability of certain microorganisms to biodegrade pollutants and convert them into less toxic compounds. Phanerochaete chrysosporium, a white-rot fungus, is recognized for its ability to metabolize a large diversity of compounds, including PCP, by the lignin degrading system. However, toxicity of PCP metabolic products generated by P. chrysosporium is not yet evaluated. The study's purpose is assessing toxicity resulting from PCP degradation by P. chrysosporium in soil and evaluating its potential usefulness in soil bioremediation. P. chrysosporium was cultured in a solid-state system consisting of glass columns packed with crushed fibrous plant residue from sugar-cane refining. Once the fungus grew, it was used to inoculate soil spiked with 100 ppm of PCP, at soil/plant residue ratio of 85/15. Under these conditions, PCP degradation kinetic study was performed for 11 days. Soil samples were collected during this period assessing PCP disappearance and soil toxicity changes using Microtox®. A significant decrease (87%) in PCP levels in contaminated soil was observed 4 days after inoculation with P. chrysosporium. During this period, soil toxicity decreased rapidly, becoming almost negligible after 11 days. These results suggested P. chrysosporium application to PCP-contaminated soil is a feasible bioremediation option, considering that this microorganism reduces PCP levels in a short period of time without generation of more toxic compounds. (C) 2000 by John Wiley and Sons, Inc.