Fermentation-Driven Biosynthesis of Natural Carotenoids in Rhodotorula glutinis P4M422: Evaluation of Culture Conditions

Carotenoids are natural pigments of high industrial value, with recognized antioxidant properties, and are widely used in the food, cosmetic, and pharmaceutical industries. Oleaginous yeasts, such as Rhodotorula glutinis, represent a promising alternative for the sustainable production of these compounds through submerged fermentation, compared to their extraction from plant sources or chemical synthesis. This study aimed to optimize culture conditions to maximize biomass and carotenoid production in R. glutinis P4M422. To this end, the effects of various culture factors, including light, carbon-to-nitrogen (C/N) ratio, temperature, pH, and glycerol addition, on cell growth and pigment biosynthesis were evaluated. The results showed that agitation speed and C/N ratio are key variables in system performance, significantly influencing both growth and carotenoid accumulation. Under the established optimal conditions (210 rpm, C/N ratio of 50, red light, and 30 °C), a maximum volumetric yield of 343.1 mg/L and a productivity of 4.8 mg/L/h were achieved, representing a substantial improvement in process efficiency. These values position the R. glutinis P4M422 strain as a competitive alternative for the biotechnological production of carotenoids. Taken together, these findings confirm the efficiency of submerged culture as a platform for obtaining high-value-added biopigments and reinforce the potential of microbial fermentation systems as a sustainable, scalable, and controllable strategy for their production.