富核糖核酸热带假丝酵母发酵培养基优化

Optimization of fermentation medium for Candida tropicalis with high ribonucleic acid

以热带假丝酵母(Candida tropicalis)AY91009为试验菌株,以其核糖核酸(RNA)含量为目标,选取糖蜜为碳源,采用响应面法对其发酵培养基进行优化,建立酵母浸粉、NH4Cl和ZnSO4·7H2O的二次回归模型,确定培养基最佳配方为:糖蜜(30%含糖量)140 mL/L、酵母浸粉2.90%、NH4Cl 1.37%、NaH2PO4·2H2O 0.10%、MgSO4·7H2O 0.20%、FeSO4·7H2O 0.05%、ZnSO4·7H2O 0.10%。在此优化培养基中发酵培养12 h,RNA含量达到11.58%,比优化前提高了35.6%。20 L罐分批发酵试验结果表明,细胞干质量达到32.38 g/L,RNA含量为6.69%,总RNA含量为2.17 g/L,为后续的高密度发酵研究奠定了良好的基础。

Using Candida tropicalis AY91009 as experimental strain, the RNA content as the target, and molasses as the carbon source, the fermentation medium was optimized by response surface methodology, and a quadratic regression model with yeast extract, NH4Cl and ZnSO4·7H2O as independent variables was established. The optimum medium formula was determined as follows: molasses (sugar content 30%) 140 ml/L, yeast extract 2.90%, NH4Cl 1.37%, NaH2PO4·2H2O 0.10%, MgSO4·7H2O 0.20%, FeSO4·7H2O 0.05% and ZnSO4·7H2O 0.10%. The RNA content reached 11.58% under the optimum medium fermented for 12 h, which was 35.6% higher than that before optimization. The results of batch fermentation experiment in 20 L fermenter showed that the dry cell mass reached 32.38 g/L, the RNA content was 6.69%, and the total RNA content was 2.17 g/L, which laid a good foundation for the subsequent high-density fermentation research.