Exploring Hydrocarbon Degradation Capacity and Mathematical Modeling of Mixotrophic Growth Kinetics in Tetradesmus obliquus and Desmodesmus armatus for Crude Oil Bioremediation

Crude oil spills imperil aquatic ecosystems globally, prompting innovative solutions such as microalgae-based bioremediation. The potential of Tetradesmus obliquus and Desmodesmus armatus for crude oil spill bioremediation is investigated in this study. Under mixotrophic conditions and varying crude oil concentrations (0.5 to 2%), both species showed decent resistance, sustaining growth, and adaptation at low crude oil exposure levels below 1%. Both algae exhibited peak growth rates at a 0.5% crude oil concentration. In T. obliquus, chlorophyll-a levels increased with 0.5% crude oil exposure, while chlorophyll-b and carotenoid levels remained fairly consistent. Conversely, D. armatus exhibited variable chlorophyll-a and carotenoid levels at the 0.5% crude oil concentration, accompanied by an uptick in chlorophyll-b levels. GC/MS analyses revealed that T. obliquus efficiently degraded aliphatic compounds like undecane, tridecane, and pentadecane. Additionally, T. obliquus outperformed D. armatus in degrading both aliphatic and aromatic hydrocarbons. The study identifies the modified Richards model efficacy for T. obliquus, while the Baranyi-Roberts model exhibited superiority for D. armatus as optimal for representing growth kinetics in response to crude oil exposure. This insight is crucial for tailored bioremediation strategies, emphasizing species-specific adaptability and concentration considerations. Overall, the study provides vital information for designing targeted approaches to address crude oil contamination challenges, contributing to effective environmental restoration in contaminated ecosystems.