Breeding Of Rhodotorula With High Carotenoids Yield And Its Pigment Purification And Identification

In this study twelve red wild strains were screened from the wild and a producing carotenoid strain named WH-4-1was rescreened. Then the strain was identified as Sporidiobolus pararoseus via morphology observation,16S rDNA analysis and phylogenetic tree. Twenty mutant strains were obtained from the parent strain WH-4-1by UV and gamma rays mutagenesis. After testing their biomass and capacity of carotenoid, the mutant strain Sporidiobolus pararoseus WZ012that can dramatically enhance the productivity of carotenoid was sereened out. The strain Sporidiobolus pararoseus WZ012has passed the stability test. Then the fermentation medium and culture conditions were preliminary optimized by univariate and response surface method. The further study on Sporidiobolus pararoseus WZ012in the orange juice fermentation was carried out, and its fermentation medium was optimized. Then it was cultured in a5L fermentor filled with the orange juice medium. Finally, the carotenoid extract from Sporidiobolus pararoseus WZ012in YEPD medium and orange juice medium was respectively separated, purified and identified initialy by thin layer chromatography, column chromatography, UV-vis and HPLC, and a comparative analysis was conducted. The major findings are as follows: 1. The best culture conditions of Sporidiobolus pararoseus WZ012in YEPD medium were as follows:glucose60g/L, yeast extract12g/L, KH2PO41.5g/L, media amount50mL/250mL, pH6.0, temperature30℃, fermentation time72h. Under this condition, the strain’s biomass and carotenoid yield are up to25.4g/L and34.1mg/L respectively, which was separately28.9%and22.3%higher than that in original fermentation condition.2. The optimal orange juice medium composition was as follows: orange juice40mL, glucose30g/L, yeast extract20g/L. After it had been cultured in that optimal medium for48h based on a5L fermentor,30℃, the strain’s biomass and carotenoid yield reached35g/L and32mg/L respectively.3. Three main kinds of carotenoids from Sporidiobolus pararoseus WZ012fermentation products were identified, they could be β-carotene, torulene and torularhodin. Carotenoids composition comparison showed the composition difference between fermentation products based on the orange juice and YEPD medium. With the presence of orange juice, torulene (61.3%) and β-carotene (38.1%) were the dominant carotenoid among the three pigments, while the main carotenoid were β-carotene (62.5%) and torulene (36.8%) with the the presence of YEPD.