Mycoremediation potential of Aspergillus ochraceus NRRL 3174

Mycoremediation is an important process that targets the removal of petroleum hydrocarbons by fungi. Fungi have advantages with their extensive enzymatic systems, rapid adaptation to toxic organic pollutants, and to adverse environmental conditions. In this study, the colorimetric method was used for the preliminary investigation of petroleum degradation with ten fungal strains. Petroleum degradation ability of spore suspension, live biomass (fungal pellet and disc) and cell-free culture supernatant of the potent A. ochraceus strain were investigated by gravimetric analysis. It was found that the fungal disc (94%) was more successful than the spore suspension (87%) in petroleum degradation under physiological conditions determined as pH:5.0, 1% of petroleum concentration, 5% (v/v) of inoculum concentration (with spore suspension) and 1 g/100 mL of inoculum amount (with fungal disc) and 7 days of the incubation period. The degradation rate constant and half-life period of spore suspension were calculated as 0.291 day^-1 and t_1/2 = 0.340 and of the fungal disc were 0.401 day^-1 and t_1/2 = 0.247. Although, 7.5% and 10% (v/v) concentration of cell-free culture supernatant achieved more than 80% petroleum removal, it was not as effective as a fungal disc. According to gas chromatography/mass spectrometry analysis, the fungal disc of A. ochraceus strain degraded long-chain n-alkanes such as C₃₅ and C₃₆ more effectively than n-alkanes in the range of C₂₂-C₃₄. The fact that the A. ochraceus NRRL 3174 strain has a high petroleum degradation capacity as well as being a potent biosurfactant producer will provide a different perspective to advanced mycoremediation studies.