Optimization of Mycoremediation Potential of A Fungi: Aspergillus Ochraceus Strain

Abstract

Mycoremediation is an important process that targets the removal of petroleum hydrocarbons by fungi. Accordingly, colorimetric method was used in the preliminary investigation of petroleum degradation with ten fungal strains as Aspergillus ochraceus, Aspergillus parasiticus, Aspergillus niger, Fusarium acuminatum, Fusarium graminearum, Fusarium equiseti, Fusarium oxysporum, Paecilomyces lilac, Penicillium crustosum, and Penicillium chrysogenum. Petroleum degradation of spore suspension, live biomass (fungal pellet and disc) and cell-free culture supernatant of the potent A. ochraceus strain were determined by gravimetric analysis. It was obtained that the fungal disc (94%) was more successful than the spore suspension (87%) in petroleum degradation under optimized conditions as pH:5.0, 1% of petroleum concentration, %5 (v/v) of inocum concentration, 1 g/100mL of inoculum amount and 7 days of incubation period. The degradation rate constant and half-life period of spore suspension were calculated as 0.291 day− 1 and t1/2 = 0.340 and of fungal disc were 0.401 day− 1 and t1/2 = 0.247. 7.5% and 10% (v/v) concentration of cell-free culture supernatant were achieved more than 80% of petroleum removal. However, the cell-free culture supernatant was not as effective as fungal disc. According to GC/MS 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. Drop-collapse and oil-spreading methods showed that A. ochraceus is a good biosurfactant producer. This study clearly pointed out that Aspergillus ochraceus NRRL 3174 strain with high its removal capacity can be used as an effective agent in petroleum bioremediation process.