Study On Technology Of Astaxanthin Biosynthesis In Phaffia Rhodozyma

Due to the powerful antioxidantive activities and pigmentation property, astaxanthin, one of a carotenoid, has broad application prospects in the food additives, aquaculture, cosmetics, and healthy care products. Recently there is increasing interest in astaxanthin biosynthesis from Phaffia rhodozyma for commercial production, but it was restricted by low-productivity of astaxanthin. Aiming directly at industrial production of astaxanthin, this paper carried out the following research:Effects of different carbon sources, nitiogen sources, inorganic salts, metallic ion, growth factors on astaxanthin biosynthesis by mutant G1051 were studied. Results showed that the rice starch hydrolysates, corn steep liquor, ammonium acetate, phosphate, some of vitamin as growth factors were advantageous with the astaxanthin accumulation. By orthogonal experiment design, a optimized medium was obtained, which was composed of rice starch hydrolysate 60 g/L, CSL 2 g/L, NH4C2H3O2 3 g/L, KH2PO4 2 g/L, Na2HPO4?4H2O 1.5 g/L, MgSO4 3 g/L and CaCl2 0.2 g/L. In this medium, the Phaffia rhodozyma biomass, astaxanthin yield and content were enhanced by 21.9%, 36.2% and 10.9% higher than that before optimization respectively.By analysis of Phaffia rhodozyma fermentation kinetics, it was found that low initial sugar was beneficial for shortening the delay period, and the higher the initial sugar concentration, the greater cell biomass. The increasing of the initial sugar concentration decreased the astaxanthin production when the rice starch hydrolysis sugar was used as the carbon source. Although the nitrogen was not consumed obviously in the process of fermentation, the protein nitrogen is conducive to the growth of Phaffia rhodozyma, and NH4+ to astaxanthin accumulation. Different phosphate concentrations showed no significant effects on cell growth and astaxanthin synthetic, although phosphate was necessary for Phaffia rhodozyma.Effects of different culture conditions on astaxanthin biosynthesis by mutant G1051 were studied. In flask cultivation, culture conditions and composition of seed medium was optimized by orthogonal design. The optimum culture conditions of the mutant was as follows: the seed age of 36 hours, inoculating of 10%, medium volume of 30 ml, shaker rotation speed of 250 r/min, adding the appropriate amount of oxygen vector, temperature 18-22°C, and pH 4-6.