一株优选酿酒酵母增殖培养条件优化及发酵动力学模型的构建

Optimizing on Proliferation Conditions of Preferred Saccharomyces cerevisiae and Construction of Fermentation Kinetics Model

为实现酿酒酵母(Saccharomyces cerevisiae)的高密度发酵及在奶啤生产中的应用,对一株来源于新疆传统发酵驼乳中的酿酒酵母TR2生长所需的增殖因子与培养条件进行研究,并建立该菌株的发酵动力学模型。采用单因素实验对培养基中的碳源、氮源以及无机盐的种类与浓度进行筛选,通过响应面试验与正交试验的方法分别优化该菌的培养基成分和发酵条件,采用Matlab软件对该菌株菌体生长和葡萄糖消耗动力学模型分别进行非线性拟合。结果表明,优化培养基配方为葡萄糖53.4 g/L、蛋白胨21.5 g/L、酵母膏10 g/L、磷酸二氢钾2.98 g/L,在初始p H值为5.0、摇床转速150 r/min、接种量体积分数5%、装液量60 m L的条件下28℃发酵16 h,细胞数量可达到6.64×108CFU/m L,其菌体生长和葡萄糖消耗动力学模型的预测值与实验值能较好地拟合,拟合度分别为0.997 3和0.978 4,表明所建模型能较好反映该菌的分批发酵过程。

This study assessed the proliferation factors and culture conditions for the growth of a Saccharomyces cerevisiae TR2 isolated from Xinjiang traditional fermented camel milk and established its kinetic model,which could reflect the high density fermentation and the application of Saccharomyces cerevisiae in milk beer production. The carbon source,nitrogen source,inorganic salts,species and concentrations of the growth factors in culture medium were screened by the single factor test. Meanwhile,the compositions of culture medium and fermentation conditions of Saccharomyces cerevisiae were optimized by response surface and orthogonal methods. Moreover,the strain growth and the kinetic model of glucose consumption were fitted nonlinearity by Matlab software. The results showed that the optimal medium was glucose 53. 4 g/L,peptone 21. 5 g/L,yeast extract 10 g/L,and KH2 PO42. 98 g/L. Under the fermentation conditions of initial p H 5,shaking speed at 150 r/min,inoculum concentration 5%,liquid volume 60 m L,incubation time 16 h and incubation temperature 28 ℃,the cell number reached to 6. 64 × 10^8 CFU/m L. The predictive value of the kinetic model for the fermentation process was well fitted to the experimental value,and the fitting degrees were 0. 997 3 and 0. 978 4. It concluded that the model could reflect the fermentation process of the strain in batches.