Fife Yeast Flask Fermentation Condition Optimization And High-yield Strains Of Astaxanthin Mutagenesis Breeding

Astaxanthin is a kind of keto carotenoid which has a powerful biological antioxidant activity and has been applied in several fields, such as in medicine, food and cosmetic et al. Phaffia rhodozyma is an important biological resource for astaxanthin, but it has several disadvantages in the synthesis of astaxanthin, such as low production of astaxanthin, low fermentation temperature and less practical value. So screening for high yield strains of Phaffia rhodozyma with normal fermentation condtions is very important both for theoretical and practical application. In present study, the fermentation conditions of P. rhodozyma had been optimized in rocking flasks by using Plackett-Burman design and Response Surface Analysis provided by SAS soft ware, and the adaptive dosages of mutagenic agents were also explored. A strain with high-yield of astaxanthin and more toleratant to high temperature UL-40 had been obtained by UV-LiCl compound mutation. The main results were as follows:1. The growth of P. rhodozyma was observed in rocking flasks during 144 hours, and the biomass, yield of astaxanthin and glucose residue in substrate were all measured. Furthermore the growth of P. rhodozyma and synthesis of astaxanthin were detected by optical microscope and fluorescent microscope. The results showed that, the yield of astaxanthin reached the maximum at 96th hour of fermentation, though at 48h of fermentation, the biomass reached the maximum and the glucose in culture medium decreased to the minimum.2. The effect of inoculation stage, rotating speed of rocking incubator, inoculum and liquid volume in flask had been studied on the growth of P. rhodozyma, and the optimal fermentation condition was obtained as follow: 48th hour, 160 rpm, 10% and 50mL respectively. Furthermore, different lysing methods and extraction solvent were compared. The results showed that acid-hot method was the most suitable lysing method and acetone was the most suitable solvent for extraction.3. The fermentation temperature, initial pH of culture solution and 6 kinds of substrate were optimized by Plackett-Burman design and Response Surface Analysis provided by SAS software. The temperature, initial pH and corn steep liquor were chosen...