Biodegradation of Crude Oil and Lignin-Modifying Enzyme Activity of White Rot Basidiomycetes

Abstract

In the present study, the ability of eighteen white-rot basidiomycetes was evaluated for crude oil biodegradation. Cerrena unicolor strains, Panus tigrinus 433, P. lecometei 903, Pleurotus ostreatus 70, Trametes maxima 403, and T. versicolor 159 showed especially abundant mycelial growth on the surface of agar covered with droplets of crude oil. In the submerged cultivation in the glucose (3 g/L) containing medium, complete decolorization of indicator Resazurin was observed during two weeks in the presence of Bjerkandera adusta 139, C. unicolor 303, Coriolopsis gallica 142, P. ostreatus 70, P. pulmonarius 148, and T. versicolor 159. When artificially oil-polluted soil was inoculated with fungal mycelium pre-grown on a mixture of wheat straw and mandarin peels the maximum degradation rate (65%) was obtained when C. unicolor 305 was incubated in the 1% oil-containing soil for 28 days. At the same cultivation conditions, P. ostreatus 2175 eliminated 43.9% of initial oil when its concentration in the soil was increased to 2%. In the lignocellulose-containing soil, neither glucose nor yeast extract enhanced oil degradation, but wetting of soil with the distilled water to maintain its humidity favored oil elimination. The tested WRB secreted lignin-modifying enzymes in the presence of petroleum hydrocarbons; the higher was the concentration of lignocellulosic substrate in the soil the higher was the fungi enzyme activity. However, the data received did not show any direct relationship between the fungi enzyme activity and the degree of oil elimination. Key words: mycoremediation, crude oil, basidiomycetes, cultivation conditions, lignin-modifying enzymes