蛹虫草静置发酵产虫草素的优化
Optimization of static fermentation for cordycepin production by Cordyceps militaris
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摘要: 对蛹虫草14014产虫草素的静置发酵培养基和发酵条件进行了优化,旨在探寻大规模制备虫草素的工艺方法。为了提高数理统计的精度,缩短发酵周期,通过单因素实验,获得了种龄为3d,接种量为10%的液体培养物最佳接种方式。通过Placket-Burman设计从7个因素中筛选出了有显著影响的温度、酵母膏和蛋白胨三个因素。通过最陡爬坡实验、中心复合实验设计及响应面分析确定主要影响因素的最佳值及回归模型,并经实验验证模型的可行性。最佳培养基组成和培养条件为:葡萄糖60g/L,KH2PO40.7g/L,MgSO4·7H2O 0.7g/L,酵母膏9.00g/L,蛋白胨17.10g/L,初始pH6.30,温度27.1℃。在优化条件下,虫草素产量达到6.50g/L,含量比优化前提高2倍。Abstract: In order to seek the technological process of large-scale cordycepin production, the fermentation medium and conditions for Cordyceps militaris CICC No.14014 to produce cordycepin in static fermentation were optimized. Based on the study of single factor tests, the optimal inoculation method was achieved with 3d seed age and 10% (v/v) inoculum size to improve the mathematic statistics precision and cut down the fermentation period. We used Plaekett-Burman design to evaluate the influence of seven related factors.Fermentation temperature and concentrations of yeast extract and tryptone were affirmed the significant factors.After identifying three critical factors, the optimal region of cordycepin production was found by steepest ascent approach. Then central composite design and response surface methodology were also used to develop a mathematical model to identify the optimum values of the key factors for higher cordycepin production, and to confirm its experimental validity. Results showed that the optimal fermentation medium and conditions were as follows:glucose 60g/L, KH2PO40.7g/L, MgSO4·7H2O 0.7g/L, yeast extract 9.00g/L, tryptone 17.10g/L, the initial pH6.30, fermentation temperature 27.1℃. Under these optimum conditions, the yield of cordycepin reached6.50g/L, which led to a 2-fold increase compared with that before.