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 oleaginous
yeasts as renewable alternatives to plant-derived and fossil-based oils, with applications in food, fuel, and material
production. The oleaginous yeast Cutaneotrichosporon oleaginosus is of industrial relevance due to its ability
to 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 application
requirements.
Results This study investigated the influence of temperature, pH, and dissolved oxygen concentration (DO) on lipid
production and fatty acid composition in C. oleaginosus ATCC 20509. A three-level, three-factor Box–Behnken design
was applied to assess their effects on lipid titer, oleate lipid titer, and the proportions of saturated and unsaturated
fatty 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 degree
of saturation. In fed-batch cultivation with consumption-based acetic acid feeding and glucose as the initial carbon
source, 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), corresponding
to 46% and 50% increases compared to literature values (0.26 g/L/h; 28 °C, pH 6.5, 50% DO). The fatty acid profile
could thus be precisely modulated by adjusting the process parameters, achieving a difference in the saturation
degree of more than 10%. Temperature was identified as the main factor influencing saturation, while pH enabled
adjustment of the C16/C18 ratio, resulting in a modulation of palmitic acid fraction within the total triglycerides
of up to 13%.
Conclusion These findings highlight the potential of optimizing cultivation parameters based on reaction surface
methodology to simultaneously improve lipid productivity and functionality by tailoring the fatty acid profile
to the desired application requirements, without resorting to genetic engineering. Moreover, these insights support
a circular bio-based economy