Increased torulene production by the red yeast, Sporidiobolus pararoseus, using citrus juice

Response surface methodology was applied to maximize the yield and production of carotenoids by Sporidiobolus pararoseus WZ012 using citrus juice. A high concentration of yeast extract and citrus juice favored carotenoid production and biomass concentration, respectively. Under optimal conditions, a more than 51 percent (from 860 to 1300 µg/g) and 62 percent (from 17.05 to 27.66 mg/L) respective enhancement in intracellular and total carotenoid production was achieved. Finally, this process was successfully upscaled in a 5-L fermentor. A comparison of the carotenoid distributions revealed that torulene (61.3%) was the dominant carotenoid when using the citrus based medium, while the main carotenoid was β-carotene (62.5%) when using the glucose medium. The present work provides an alternative method to produce high-value products derived from waste and low-grade citrus.