Lipid and carotenoid production in cane molasses by Rhodosporidium toruloides mutant
Cane molasses, as a low-cost carbon source, is suitable for the lipid and carotenoids yields in microalgae or microorganisms. In this study, we investigated the lipid and carotenoid production profile of R. toruloides mutant M18 (MT) in a defined media with various amounts of pretreated cane molasses (TM) under nitrogen-limited conditions. The production of palmitic acid (C16:0) and α-linolenic acid (C18:3) from MT were improved by 16.92% and 21.88% in 100% TM compared to the wild type strain (WT). The torularhodin, torulene and β-carotene content of the MT with cane molasses under nitrogen-limited conditions were 14.68, 1.41 and 1.11-fold higher than that of the WT, respectively. Compared with the effects of cane molasses concentrations on lipid production, we found that cane molasses concentration of 35 g/L (50% TM) and 70 g/L (100% TM) as a low-cost carbon source, is an economical and green strategy for the production of lipid and carotenoids by MT, respectively. Transcriptome sequencing and WGCNA analysis revealed that differentially expressed genes in blue module were identified as significantly highly expressed and were relevant and consistent with the results of phenotype performance of lipid and carotenoids accumulation responses to the stress in cane molasses under nitrogen-limited conditions between the MT and WT strains, including MYB, bHLH, Δ-4 desaturase, Δ-12 desaturase and FA2H genes. Cane molasses, as an alternative to glucose-based medium, is suitable for lipid and carotenoid yields in R. toruloides, which makes it serve as a valuable reference for a cost-saving substance in industrial applications.