β-Carotene Production by Oleaginous Yeasts in a Pilot Plant Fermenter: Yield Standardization and Process Scale-Up

This study reports selective β-carotene pigment production by an oleaginous yeast, Rhodotorula mucilaginosa IIPL32 (MTCC 25056), in a 500 L fermenter working scale with a practically feasible approach for microbial pigment production scale-up from small (500 mL) to pilot scale (500 L) submerged fermenters using medium rheology and fermenter hydrodynamics. The pigment production was initially standardized by optimizing the carbon and nitrogen load of the fermentation medium. The pigment was purified using a solvent extraction process followed by thin-layer chromatography and analyzed by UV-visible spectrophotometry, high-pressure liquid chromatography, and Fourier-transform infrared spectroscopy, suggesting the dominant presence of β-carotene. Using 20 g/L glucose as a carbon feed, a 500 L fermenter yielded 3.3 kg yeast cell biomass and 5.1 g β-carotene. It was concluded that the process is scalable at an industrial level and could be integrated with any existing lipid biorefinery without any additional modification in Capex, thus substantially lowering the microbial lipid production cost.