Rational Selection Of Astaxanthin High-producing Strain And Optimization Of Fermentation

The natural astaxanthin has been widely applied in food, medicine, feed, aquatic products and cosmetic industry and so on, because of its special effect that contains strong oxidation resistance; inhibiting tumor growth, enhancing immunity, coloring and scavenging radical in vivo and so on. Phaffia rhodozyma is the most potential microorganism to produce natural astaxanthin in the industrial production. Improving the yield of astaxanthin by Phaffia rhodozyma using fermentation is the key technology of producing astaxanthin. The application of new technologies and new theories is the foundation of improve yield of astaxanthin by Phaffia rhodozyma. The wall breaking method of astaxanthin from Phaffia rhodozyma, rational selection of producing strain and optimization of medium of shaking flask fermentation process were investiqated by technology of modern statistics analysis,modern biotechnology and modern fermentation technology. The mainly results obtained from this study are as follows:1. The high yield strain of astaxanthin was rational screened using the resistances copper sulfate,β-ionone and diphenylamine by multiple UV mutagenesis, microwave irradiation. A mutant strain TY-I-8, with a better genetic stability and higher astaxanthin yield, was gained finally. The astaxanthin yield of this strain was 4.9 times higher than that of the original strain.2. In the study the corn steep liquor was initial fermentation medium and the medium of shaking flask fermentation was optimized. The experiment shown 1% corn steep liquor was the best nitrogen source, glucose: sucrose (1:3) was the best carbon source. On the based, optimization of fermentation was gone. The regression equation was got by canonical analysis of response surfaceY=13.96027+0.022438×X2-0.023625×X3-0.047887×X5-0.064171×X2×X2+0.00925×X2×X3-0.001125×X2×X5-0.081946×X3×X3+0.0277×X3×X5-0.071221×X5×X5. After model predictive and verification test, the optimum conditions about fermentation conditions that were initial pH6.0, broth content 28.3mL/mL, inoculation amount of 5.8%, temperature was 20℃and the rotation speed was 200r/min. The yield of astaxanthin was 8.61% higher than the initial yield.3. The wall-broken and extraction process by dimethyl sulfoxide with microwave-assisted was optimized by the response surface method. The regression equation was got by canonical analysis of response surface Y=1508.139+11.6675×X2-12.285×X3-24.9015×X5-17.76883×X2×X2+4.81×X2×X3-0.585×X2×X5-27.01183×X3×X3+14.404×X3×X5-21.43483×X5×X5. The optimum conditions about wall-breaking and extracting were dimethyl sulfoxide (51 mL/g), anhydrous alcohol (214 ml/g), cell wall breaking time (2.6 min), extracting time (15.1 min), extracting temperature (50 oC) and microwave frequency under low tap position (416.5 MHZ), after model predictive and verification test. Under this condition the yield of astaxanthin was 21.56% higher than the initial yield.