Biodegradation of Benzo[a]pyrene in Soil by Immobilized Fungus

Abstract

Mucor sp., a filamentous fungus capable of degrading polycyclic aromatic hydrocarbons (PAHs), was immobilized on maize cob (MC) by physical adsorption and used to degrade benzo[a]pyrene (BaP). The characteristics of BaP degradation by both immobilized and free fungus were then investigated and compared. The degradation rate using the immobilized fungus was higher than that of the freely mobile fungus. When the initial BaP concentration was 50 mg · kg⁻¹, the removal rate was 68% within 42 days using immobilized fungus but only 52% for free fungus in that same time. The optimal amount of inoculated immobilized fungus for BaP degradation was shown to be 2%. The immobilized fungus also showed better removal efficiencies of BaP than free fungus, independent of the moisture content. The increasing concentration of BaP was better tolerated and more quickly degraded by immobilized fungus than by free fungus when the initial BaP concentration was in the range of 10 to 200 mg · kg⁻¹. The scanning electronic microscope (SEM) analysis showed that the immobilized microstructure was suitable for Mucor sp. growth. The results demonstrate the potential for employing Mucor sp., immobilized on MC, for in situ bioremediation of PAH-contaminated soil.