Evaluation of the Effectiveness of Fungi (Candida Tropicalis and Aspergillus Clavatus) in Bioremediation of used Engine Oil Contaminated Soil using Bioaugmentation Technique

Used engine oil is a petroleum or synthetic oil that has been used and as a result of such use, is contaminated by physical and chemical pollutants. These pollutants are harmful to humans, animals and plants following exposure. Evaluation of the effectiveness of fungi in bioremediation of used engine oil (UEO) contaminated soil was investigated. Fungi were isolated from soil samples obtained from automobile workshops in Mgbuka-Nkpor, Nigeria. The isolates were screened for UEO biodegradation potentials in mineral salt broth. They were identified using the cultural and microscopic characteristics and confirmed using the 18SrRNA gene sequence. The effectiveness of the isolates in bioremediation of UEO contaminated soil was also investigated using bioaugmentation technique. A total of 8 fungal isolates were obtained from this study. Two that showed the highest extent of biodegradation of UEO in the screen flasks were identified and confirmed as Candida tropicalis and Aspergillus clavatus. At the end of the experimental period, oil contaminated soil inoculated with the mixed culture of the isolates (C. tropicalis and A. clavatus) showed the highest reduction in concentration of UEO (95.42%). Higher biodegradation rate and shorter half-life of total petroleum hydrocarbon (TPH) was observed in soil microcosm containing the isolates, when compared to the uninoculated control. Therefore fungi such as C. tropicalis and A. clavatus isolated from automobile workshops can facilitate the bioremediation of UEO contaminated soil.