High temperature drives torularhodin-dominant carotenoid overaccumulation in Rhodosporidiobolus odoratus XQR via...

Carotenoids are bioactive pigments widely used in food, pharmaceutical, and cosmetic industries. Rhodosporidiobolus odoratus co-produces commercially significant carotenoids, including β-carotene, torulene, and torularhodin. This study aimed to reveal how carotenoid biosynthesis in R. odoratus XQR, optimally grown at 20 °C, responds to low (10 °C) and high (30 °C) temperatures. After five days, total carotenoids reached 118.55 μg/g DCW and 0.40 μg/mL at 30 °C, ∼3-fold higher than the 20 °C control (41.25 μg/g DCW and 0.14 μg/mL). Torularhodin showed a pronounced increase at 30 °C (37.26 μg/g DCW and 0.12 μg/mL), ∼9-fold above the control (4.06 μg/g DCW and 0.014 μg/mL). At 10 °C, total carotenoids declined to 26.09 μg/g DCW, with a slight, non-significant rise in volumetric titer to 0.17 μg/mL. High temperature elevated reactive oxygen species (ROS) and superoxide dismutase (SOD) activity while reducing total protein, whereas low temperature maintained stable ROS, induced moderate SOD, and caused protein decline; catalase (CAT) activity changed minimally under both conditions. Our integrated data suggest that high temperature promotes carotenoid overaccumulation through upregulation of key terpenoid backbone biosynthetic genes (HMGCS, hmgA, and mvaD) and carotenogenic genes (crtYB, crtI, crtZ, and crtA), coupled with a metabolic shift that enhanced precursor supply. These coordinated responses explain torularhodin-dominant accumulation and differ from related yeasts, suggesting species-specific regulation. This work provides new mechanistic insights into temperature-driven carotenogenesis in R. odoratus XQR and highlights targets for metabolic engineering.