Pentachlorophenol to Humic Soil by the Action of White Rot Fungi

The fate of 14C-pentachlorophenol (14C-PCP) in soil inoculated with each of four wood degrading fungi was studied. After 9 wk of incubation with the fungi, the majority of the 14C (between 34 and 65%) was found bound to humic (HA), fulvic acid (FA) and humin, with lesser amounts found in the organic-extractable fraction or mineralized. The highest amounts of PCP were bound to HA (20-36% , compared to 7.5-8.3% in the uninoculated controls). Binding to FA and to humin was lower, ranging between 8.7 and 17.5% and 4.8 and 11.1% , respectively, in the fungal cultures. In control experiments around 5% of the radioactivity was found associated to FA and between 2 and 4% to the humin. The highest binding of PCP to the humic materials was obtained with Pleurotus ostreatus, followed by Irpex lacteus, Trametes versicolor and Bjerkandera adusta. Mineralization of PCP from soil cultures by the fungi was low. The fungus that mineralized the most PCP was T. versicolor, converting 8.8% of 14C-PCP into 14CO2, compared to 0.6% mineralized in the uninoculated controls. Methylation of PCP to pentachloroanisole by the fungi was low, ranging between 0 and 6.8% after 9 wk. © 1997