Recovery from Moderate H ₂ O ₂ Stress Stimulates Carotenoid Biosynthesis in <i>Rhodosporidiobolus odoratus</i> 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. <i>Rhodosporidiobolus odoratus</i>, an oleaginous red yeast, produces high-value carotenoids, including β-carotene, torulene, and torularhodin. This study investigated the impact of initial H₂O₂ additions (5, 10, 20, 30, 40, and 50 mM) on carotenoid production in <i>R. odoratus</i> XQR. Treatment with moderate H₂O₂ (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 (<i>HMGCS</i>, <i>hmgA</i>, <i>mvaK2</i>, and <i>mvaD</i>) and dedicated carotenogenic genes (<i>crtYB</i>, <i>crtI</i>, <i>crtZ</i>, and <i>crtA</i>) together with downregulation of lipogenesis and β-carotene-derived apocarotenoids, implicating precursor reallocation and attenuation of apocarotenoid volatiles as synergistic mechanisms. The findings elucidate H₂O₂-mediated regulation of carotenogenesis in this yeast, providing metabolic engineering targets for yield improvement.