VALUABLE Influence of process parameters on single‑cell oil production by Cutaneotrichosporon oleaginosus using response surface methodology

Background The growing demand for sustainable lipid sources has fostered interest in single-cell oils from oleaginousyeasts as renewable alternatives to plant-derived and fossil-based oils, with applications in food, fuel, and materialproduction. The oleaginous yeast Cutaneotrichosporon oleaginosus is of industrial relevance due to its abilityto accumulate in excess of 60% (w/w) of its dry cell weight as lipids, while metabolizing a broad range of substrates.However, economic feasibility depends on improving productivity and adapting fatty acid profiles to applicationrequirements.Results This study investigated the influence of temperature, pH, and dissolved oxygen concentration (DO) on lipidproduction and fatty acid composition in C. oleaginosus ATCC 20509. A three-level, three-factor Box–Behnken designwas applied to assess their effects on lipid titer, oleate lipid titer, and the proportions of saturated and unsaturatedfatty acids. Response surface methodology was used to develop quadratic models, identify optimized conditions,and predict fatty acid compositions. Temperature and pH significantly affected both overall lipid titer and degreeof saturation. In fed-batch cultivation with consumption-based acetic acid feeding and glucose as the initial carbonsource, lipid productivity increased to 0.38 g/L/h under the optimized oleate lipid titer condition (27.6 °C, pH 5.6,10% DO) and to 0.39 g/L/h under the optimized saturated fatty acid condition (30 °C, pH 7.0, 10% DO), correspondingto 46% and 50% increases compared to literature values (0.26 g/L/h; 28 °C, pH 6.5, 50% DO). The fatty acid profilecould thus be precisely modulated by adjusting the process parameters, achieving a difference in the saturationdegree of more than 10%. Temperature was identified as the main factor influencing saturation, while pH enabledadjustment of the C16/C18 ratio, resulting in a modulation of palmitic acid fraction within the total triglyceridesof up to 13%.Conclusion These findings highlight the potential of optimizing cultivation parameters based on reaction surfacemethodology to simultaneously improve lipid productivity and functionality by tailoring the fatty acid profileto the desired application requirements, without resorting to genetic engineering. Moreover, these insights supporta circular bio-based economy