Carotenoids are a group of tetraterpene pigments widely used in the food, pharmaceutical, and cosmetic industries. Torulene, torularhodin, and β-carotene, three principal carotenoids synthesized by Rhodotorula glutinis ZHK, possess strong health-promoting properties such as antioxidant, provitamin A, and antitumor. Here, the effect of different salt conditions on carotenoids production of R. glutinisZHK was investigated. The results showed that the total carotenoids were significantly enhanced in 0.5 M (3.91 mg/L) and 0.75 M (5.41 mg/L) NaCl treatments than that in 1.0 M (0.35 mg/L) and control (1.42 mg/L) after 120 h of cultivation. Of which, the increase in torulene and torularhodin production acts as the main contributor to the enhancement of total carotenoids. Transcriptome profiling revealed that salt stress efficiently promotes the gene expression of crtI, which could explain the molecular mechanisms of the enhanced torulene and torularhodin production under salt stress. Further experiments indicated that torulene and torularhodin play an important role in quenching excrescent reactive oxygen species induced by salt stress. Together, the present study reports an effective strategy for simultaneously improving torulene and torularhodin production in R. glutinis ZHK.
Microbial carotenoids and lipids are two groups of versatile biomolecules widely used in the food, fuel, pharmaceutical, and cosmetic industries. Rhodotorula glutinis is one of the best-known oleaginous red yeasts that has the remarkable capability to produce an assortment of valuable carotenoids and lipids. Here, the effects of different concentrations of TiO 2 and H 2 O 2 treatments on carotenoid and lipid production in R. glutinis ZHK were investigated. After 120 h of cultivation, the total amount of carotenoids was significantly increased in the TiO 2 (100 mg/L: 23.165 μg/gdw, 750 mg/L: 19.65 μg/gdw) and H 2 O 2 (5 mM: 21.51 μg/gdw, 10 mM: 118.858 μg/gdw) treatments than the control (6.099 μg/gdw). In contrast, as compared to the control, the relative abundance of total lipids was significantly decreased in the TiO 2 (100 mg/L) and H 2 O 2 (10 mM) treatments, respectively. In response to TiO 2 and H 2 O 2 stresses, the increased carotenoids were probably attributed to the down-regulated lipid biosynthesis flux, while the decreased lipids might be ascribed to the down-regulated fatty acid biosynthesis flux. Our results presented herein not only provide an effective strategy for modulating carotenoid and lipid biosynthesis in R. glutinis ZHK but also reveal the molecular foundation to further enhance their bioproductivity by molecular manipulation.
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