A new study published in the World Journal of Microbiology and Biotechnology reports a significant breakthrough in the bioremediation of used engine oil (UEO) using a newly identified lipase enzyme sourced from the mesophilic yeast Pichia caribbica PC5703. The research addresses the global challenge of improper UEO disposal, which contaminates soil, groundwater, and aquatic systems.
The study highlights that used engine oil, a hazardous pollutant containing long-chain hydrocarbons and heavy metals, continues to be discharged into the environment despite regulations. To develop a sustainable alternative, researchers produced lipase by cultivating the yeast strain in detoxified corncob hydrolysate using used cooking oil (UCO) as a low-cost inducer.
Optimization trials showed that the enzyme reaches peak activity at pH 7 and 25°C, yielding 70 IU/mL of lipase. Screening assays—including phenol red, spirit blue, and tributyrin tests—confirmed strong lipid hydrolysis.
In biodegradation experiments, the crude lipase degraded 46 ± 1.05% of UEO in 15 days, outperforming commercial Candida rugosa lipase, which only achieved 30% degradation under the same conditions. GC–MS analysis demonstrated the disappearance of several hydrocarbon peaks and the emergence of new compounds such as hexadecane, indicating breakdown of complex aliphatic fractions. FT-IR spectra further confirmed the formation of new functional groups, including O–H and C=O stretches, signalling conversion into less toxic derivatives.
The findings emphasize dual sustainability benefits: transforming waste cooking oil into an enzyme production feedstock and degrading harmful petroleum contaminants. The authors propose extended incubation studies and environmental safety assays in future research to validate long-term applications of PC5703 lipase in bioremediation.
Reference
Tracy, P., Dasgupta, D., Ashok, P.P. et al. Enzymatic biodegradation of used engine oil using a novel lipase derived from renewable feedstocks. World J Microbiol Biotechnol 41, 448 (2025). https://doi.org/10.1007/s11274-025-04650-x
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