Biotransformation Studies on Fluoranthene, a Four-ring Polycylic Aromatic Hydrocarbon, by White-rot Fungus Armillaria sp. F022

Armillaria sp. strain F022 is capable of degrading a wide range of four-ring aromatic hydrocarbons such as fluoranthene. Production of ligninolytic enzymes during fluoranthene degradation by Armillaria sp. F022 is related to an increase in biomass. Armillaria sp. F022 has been shown to degrade a 10 mg/L solution by 100% within 30 d. Fluoranthene removal decreases with an increase in fluoranthene concentrations. The highest cell weight of Armillaria sp. F022 was showed in the 10 mg/L of fluoranthene culture (≥4,400 mg/L) after 30 d of incubation. Three fluoranthene metabolites were isolated from the culture medium and analyzed by a thin layer chromatography (TLC), UV visible absorption and gas chromatography–mass spectrometry (GC-MS). The oxidation of fluoranthene is initiated by deoxygenation at the C-2,3 and C-7,8 positions. Naphthalene-1,8-dicarboxylic acid, benzene-1,2,3-tricarboxylic acid, and phthalic acid were identified by GC-MS to be present in silylated forms. Two ligninoytic enzymes, namely, laccase and 1,2-dioxygenase, were revealed during the fluoranthene degradation. The results indicate the presence of complicated processes for the regulation of fluoranthene-degrading enzymes.