Isolation and Characterization of Hydrocarbon Degrading Fungi from Used (Spent) Engine Oil Polluted Soil and Their Use for Polycyclic Aromatic Hydrocarbons (PAHs) Degradation

摘要

Fungi capable of effectively degrading and cleaning up hydrocarbons was isolated from soil samples contaminated with used engine oil at auto-mechanic workshops (at Mgbuka-Nkpor, Nigeria) using vapour phase transfer method. The ability of the potential isolates to utilize used engine oil, diesel and petrol were assessed using gravimetric method. The ability of both the pure and consortium culture of the best potential strains to degrade the polycyclic aromatic hydrocarbons (PAHs) component of used engine oil, diesel and petrol was assessed using Gas Chromatography. A total of 8 fungal isolates were identified in this study based on their cultural and microscopic characteristics. Of these, 4 that showed high promise for hydrocarbon bioremediation potentials in screen flasks were confirmed as Candida tropicalis, Rhodosporidium toruloids, Fusarium oxysporium and Aspergillus clavatus based on their 18S rRNA gene sequencing. High biodegradation efficiency (> 70%) was recorded in the PAHs component in used engine oil, diesel and petrol with both the pure and consortium culture of the best potential strains; C. tropicalis and A. clavatus, within 16 days of incubation at 28℃. However, there was complete (100%) depletion of some PAHs such as anthracene, naphthalene, acenaphthalene, acenaphthylene, phenanthrene and benzo (k) fluoranthene) in the hydrocarbon substrates with the pure and consortium culture of the isolates within 16 days of incubation at 28℃. Both the pure and consortium culture of the isolates (Candida tropicalis and Aspergillus clavatus) could therefore be utilized in the bioremediation of used engine oil, diesel and petroleum, as well as PAHs contaminated soil.