Pcb biodegradation in aged contaminated soil: Interactions between exogenous Phanerochaete chrysosporium and indigenous microorganisms

This work investigated whether the interaction between the white-rot fungus Phanerochaete chrysosporium and indigenous microorganisms could enhance po lychlorinated biphenyl (PCB) removal from historically contaminated soil in aerobic microcosms. The PCB mixture was composed mainly of 14% tri-, 20% t etra-, 9% penta-, 17% hexa-, 26% hepta-, 11% octa-, and 3% nona-chlorobiphe nyl (CB) congeners, determined by GC/MS. The fungus, which was grown on sug arcane bagasse and added via this solid substrate, successfully colonized t he contaminated soil. The added fungi and the indigenous soil community bio degraded most PCB congeners, with removing efficiencies ranging from 13% to 100% for the 45-day incubation period. The interaction between the fungus and the microorganisms present in the added bagasse inhibited both heterotr ophic activity (measured by CO2 evolution) and PCB degradation, suggesting a possible antagonism. In contrast, analysis of variance (ANOVA) inferred a synergistic effect between fungus and soil microorganisms, which resulted in a heterotrophic activity above 2.5 Mg-CO2/ g-initial dry matter/day. The statistical analyses also showed that the presence of fungus alone was par ticularly beneficial for the removal of penta- and hepta-CB.