Waste Sunflower Oil as a Feedstock for Efficient Single-Cell Oil and Biomass Production by Yarrowia lipolytica.

In this study, single-cell oil (SCO) production from waste sunflower oil was optimized using Yarrowia lipolytica IFP29 (ATCC 20460). Optimizations were performed via a multi-response approach based on the Taguchi orthogonal array design (L16), targeting maximum biomass concentration and lipid content (based on dry cell weight). A total of 16 experimental conditions were tested with five key parameters: nitrogen concentration (0, 1, 2, and 4 g/L), WCO concentration (20, 40, 60, and 80 g/L), Tween 80 content (0, 0.5, 1, and 2%) as well as the application of sonication and sterilization. Analysis of variance revealed that all tested factors, except Tween 80 and sonication, had statistically significant effects on lipid content (p < 0.05). The highest lipid content (72.86% of dry cell weight) was obtained in a sterilized, sonicated medium containing 80 g/L WCO and 2% Tween 80, under conditions without nitrogen supplementation. In contrast, maximum biomass production (4.18 g/L) was achieved in sterile cultures with high nitrogen (4%) and high WCO (80 g/L) in the absence of Tween 80 and sonication. Palmitic acid (C16:0) content was also successfully optimized, with nitrogen concentration and Tween 80 supplementation exerting a statistically significant effect (p < 0.05). These results highlight the potential of waste sunflower oil as a low-cost feedstock for SCO production and support the development of economically and environmentally sustainable bioprocesses.