LED-Illuminated Bioreactor as a Novel Strategy to Maximize Carotenoid Production by Rhodotorula mucilaginosa LB-01

Microbial synthesis of carotenoids offers a sustainable and scalable alternative to plant-based production. In this study, a novel yeast strain, Rhodotorula mucilaginosa LB-01, was isolated and evaluated for its carotenoid-producing capacity. Culture medium optimization revealed that the highest yield (10.13 Abs/g biomass) was achieved with 10 g/L glucose and 3 g/L yeast extract. The impact of LED light on pigment synthesis was then assessed, with blue LED light significantly enhancing carotenoid production to 12.4 Abs/g surpassing red, orange, white, and green light treatments. Scale-up in a 2.5 L stirred-tank bioreactor under blue LED illumination further increased carotenoids yield to 16 Abs/g (311 µg/g dry biomass), representing a 20% improvement over control conditions. Pigment purification identified three major carotenoids: torularhodin (173 µg/g), torulene (71 µg/g), and β-carotene (67 µg/g), all at higher quantity compared to the control. These findings demonstrate that R. mucilaginosa LB-01, combined with targeted LED exposure, represents a promising platform for enhanced carotenoid production.