Umudike Journal of Engineering and Technology

Crude oil contamination poses serious ecological and health risks across Nigeria, including in non-oil-producing areas like Ilorin, Kwara State. While bacterial bioremediation has been widely studied, limited research exists on the potential of indigenous oleaginous yeasts such as Yarrowia lipolytica for hydrocarbon degradation in inland environments. This study aimed to isolate and evaluate the bioremediation capacity of Y. lipolytica from oil-contaminated soil in Ilorin under controlled laboratory conditions. Soil samples were subjected to microbiological analysis, and the dominant yeast isolate was identified using ITS sequencing, confirming 99–100% similarity with Y. lipolytica reference strains. Biodegradation was assessed over 20 days by monitoring surface tension, emulsification index, and enzyme activities. The isolate achieved 90.1% Total Petroleum Hydrocarbon (TPH) reduction within 20 days. Emulsification index rose to 80%, and surface tension dropped from 72 to 30 mN/m, indicating biosurfactant production. Peak enzyme activities were observed at day 15: lipase (6.0 U/mL), monooxygenase (3.8 U/mL), and catechol 2,3-dioxygenase (3.1 U/mL). FTIR and GC-MS analyses confirmed oxidative degradation and emergence of new metabolites.These findings highlight Y. lipolytica as an effective agent for mycoremediation, offering a sustainable, low-cost strategy for restoring petroleum-contaminated soils in Nigeria’s urban and semi-urban regions.