法夫酵母高产虾青素的选育及发酵条件的优化

对法夫酵母原始菌株进行了紫外线－氯化锂复合诱变，获得了一株遗传性状稳定、在25℃条件下虾青素高产的菌株UL-40。其类胡萝卜素产量为7.10mg/L，经HPLC测定，其虾青素产量为643.97μg/g，比出发菌株提高了249.87%。利用SAS软件中的Plackett-Burman设计对发酵温度、初始pH值以及发酵培养基的八种组分进行优化组合，从中选出发酵温度、初始pH值和Corn steep liquor浓度为重要因素，通过响应面分析法建立了模型并从该模型中计算出在发酵温度为16.78℃、初始pH为4.73和CSL浓度为7.06mg/L时预测的最大响应值为3.9407mg/L，经实验证实此点的实测值为3.9261mg/L，证明模型是有效的并且存在极大值点。采用优化后的发酵条件及发酵培养基，法夫酵母生产虾青素的产量较原始发酵培养基提高了20.4%。

Mutagenesis Screening of Astaxanthin-producing Phaffia rhodozyma and Fermentation Condition Optimization

The original strain was treated with UV combining LiCl. The result showed that strain UL-40 has a good stability and higher capacity to synthesize astaxanthin under 25℃. The total carotenoid yield was 7.10mg/L. HPLC analysis showed that the maximal yield of astaxanthin of the selected strain had reached 643.97μg/g, which was 249.87% higher than that of the initial strain. 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 as the major factors from all the 8 variables, a regression model equation was obtained after regression analysis performed on the data from RSA experiment. The optimal conditions were predictted to be 16.78℃, pH4.73 and 7.06 mg/L, respectively, for the maximum carotenoid production. Under these conditions, the theroretical maximal yield of carotenoid was 3.9407 mg/L. The model was validated experimentally and the practical maximal yield of carotenoid was about 3.9261mg/L. The carotenoid production was increased by 20.4% when P. rhodozyma was cultivated under the optimal conditions as compared with the control.