Recovery from Moderate H 2 O 2 Stress Stimulates Carotenoid Biosynthesis in Rhodosporidiobolus odoratus XQR via Precursor Reallocation and Attenuation of Apocarotenoid Volatiles

Carotenoids are natural pigments with vibrant colors and bioactivities, widely used in food, pharmaceutical, and cosmetic industries. Rhodosporidiobolus odoratus, an oleaginous red yeast, produces high-value carotenoids, including β-carotene, torulene, and torularhodin. This study investigated the impact of initial H 2 O 2 additions (5, 10, 20, 30, 40, and 50 mM) on carotenoid production in R. odoratus XQR. Treatment with moderate H 2 O 2 (20 mM) for 120 h maximized carotenoid production at 66.03 μg/g (1.59-fold the control), with respective changes in β-carotene (1.67-fold), torulene (0.72-fold), and torularhodin (3.52-fold). Integrated multiomics analyses suggest that enhanced carotenogenesis likely results from coordinated upregulation of mevalonate pathway genes ( HMGCS, hmgA, mvaK2, and mvaD ) and dedicated carotenogenic genes ( crtYB, crtI, crtZ, and crtA ) together with downregulation of lipogenesis and β-carotene-derived apocarotenoids, implicating precursor reallocation and attenuation of apocarotenoid volatiles as synergistic mechanisms. The findings elucidate H 2 O 2 -mediated regulation of carotenogenesis in this yeast, providing metabolic engineering targets for yield improvement.