Transcriptomic and metabolomic analysis reveals the potential mechanisms underlying the improvement of β-carotene and torulene production in Rhodosporidiobolus colostri under low temperature treatment

Carotenoids are a group of versatile isoprenoid pigments widely utilized in the food, pharmaceutical and cosmetic industries. Rhodosporidiobolus colostri is a cold-adapted yeast that has piqued interest as a natural source of microbial carotenoids, including beta-carotene, torulene and torularhodin. Here, the effect of low temperature on carotenoid production in R. colostri was investigated. The results indicated that the total carotenoid production was significantly increased at the low temperature (16 degrees C) treatment (29.016 mg/L) as compared to control (25 degrees C) (17.147 mg/L) after 5 days of cultivation. Among them, the increase in beta-carotene and torulene serve as the main contributors to the improvement in total carotenoid production. Integrative analyses of the transcriptome and metabolome suggested that the up-regulation of the terpenoid backbone biosynthesis pathway and the down-regulation of the TCA cycle flux allow more acetyl-CoA to be diverted to carotenogenesis, which might be the reason for the increased production of beta-carotene and torulene in R. colostri under low temperature treatment. Our results presented herein should not only provide an effective strategy for increasing total carotenoids pro-duction in R. colostri, but lay the molecular groundwork to further facilitate genetic engineering to enhance the yield of certain carotenoids.