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Mutagenesis And Protoplast Fusion Of Phaffia Rhodozyma And Optimazation Of Fermentation

Posted on:2004-08-13Degree:DoctorType:Dissertation
Country:ChinaCandidate:X Q TianFull Text:PDF
GTID:1101360185974175Subject:Fermentation engineering
Abstract/Summary:PDF Full Text Request
The mutagenesis and screening of Phaffia rhodozyma, flask and bioreactor cultivation of astaxanthin-overproducing mutant , promotion of fermentation additives on the astaxanthin synthesis, protoplast fusion between astaxanthin -overproducing mutant and 5. cerevisiae , and fermentation characteristics of fusion cell were studied.By repeating mutagenesis on Phaffia rhodozyma with NTG and screening with diphenylamine and β-ionone, an astaxanthin-overproducing mutant NT221 was obtained. The astaxanthin content of 1, 200μg/g in flask culture with YM was reached ,which was 50% higher than the parent. The research showed that the resistance of mutant NT221 to yeast inhibitors such as 2-deoxy-D-glucose, nystatin, antimycin A, actidione and CuSO4 was stronger than the parent. Adding 500mg/L CuSO4 to medium helped to stop degeneration of carotenoids synthesis.The effects of temperature, pH, media volume and inoculation concentraton on the biomass, astaxanthin content and yield in flask culture were investigated. The optimum temperature and pH for growth were 20°C and 4.0 respectively. The optimum temperature and pH for astaxanthin synthesis were 20℃ and 5.0 respectively. The lower media volume was in favor of the yeast growth and astaxanthin synthesis; The inoculation concentratons of 510% were in favor of the biomass and astaxanthin synthesis.The results of orthogonal designs L16(45) showed that media volume is the best significant factor of all the 5 factors affecting the growth and astaxanthin synthesis such as temperature, pH, media volume, inoculation concentraton and culture time. The second one is temperature.Glucose, raffinose and sucrose were the best carbon sources for growth and astaxanthin synthesis of Phaffia rhodozyma mutant NT221. The best nitrogen source were peptone, yeast extract and corn slurry. K2HPO4 was the best beneficial to the astaxanthin synthesis among the four phosphate. Using orthogonal designs L16(45) , the optimal flask medium was obtained: glucose20g/L, corn slurry 5 g/L, K2HPO4 1 g/L , MgSO4 2 g/L, yeast extract 3 g/L.The research on the 5L bioreactor culture of mutant NT221 showed that: the biomass and astaxanthin content by fed-batch was much higher than those...
Keywords/Search Tags:Phaffia rhodozyma, astaxanthin, mutagenesis, protoplast fusion, fermentation
PDF Full Text Request
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