Study On Hyper Producing Astaxanthin By Microbiological Method

As a singular antioxidant agent, astaxanthin became the research focus. But that producingastaxanthin by fermentation method was restricted by low yield, strict condition and high cost.The dimethylsulphoxide (DMSO) method was optimized firstly. Under the optimumcondition, the pigment concentration in the extracting liquid was1.8mg/L, which increased67%comparing with the contro(l1.2mg/L), and the pigment was stable when treated by heatand light.To increase the astaxanthin content in Phaffia rhodozyma, Ultraviolet light and H2O2wasused to create and diphenylamine was used to screen pigment over-producing mutant in thisstudy. One mutant designed UV-801e-S015was selected. The pigment producing wasenhanced significantly with two rounds of UV inducing (30w,20cm) for80s and15mmol/LH2O2treating at0h-old-age, reaching the pigment production of5.56mg/L and the biomassyield of12g/L, which were111%and28%higher, respectively, than the control (2.63mg/L,9.4g/L). The genetic instability was stable within10passages. The effect of4℃lowtemperature on the yeast was tested. The result showed that the pigment production ofUV-801e was increased by treated for84h. The benefit effect was occurred on many mutantsby treated for suitable time, but the simultaneous to the wild strain and some mutant.The fermented conditions of the mutant UV-801e-S015were studied. The results showedthat the temperature and the concentrations of C-source and N-source had obvious effects ongrowth rate and astaxanthin production. The suitable temperature for biomass was23℃,while that was20℃for astaxanthin production, and the suitable compositions of themedium were different too. Finally a two stages fermentation method was found, the dividedline was60h, and the medium and temperature was different because of the different point.The results showed that the growth rate, pigment production and biomass of the mutant wereenhanced significantly with cultured in this method.