菜籽粕脱毒菌株培养基的优化研究

Optimization of Culture Medium of Multiple Strains for Reduction of Toxicity in Rapeseed Meals

在菜籽粕的微生物脱毒工艺中,目前主要采用几种菌株复配作为发酵菌剂。为了在较短的时间内获得大量生产用微生物菌体,本研究采用Plackett-Burman设计对影响复配脱毒菌剂中菌体生长总量的培养基成分进行了评价。结果表明,氯化钾、硫酸镁、磷酸氢二钾、硝酸钠、蔗糖的含量对菌体的生长总量影响显著。在此基础上,采用响应曲面法对各关键因子的最佳水平进行了优化,得到最佳培养基组成为:蔗糖32.5g/L,氯化钾2.4g/L,磷酸氢二钾1.5g/L,硫酸镁0.48g/L,硝酸钠4.0g/L,自然pH。验证实验表明,在此工艺下,复合菌株菌体生长总量达到最大值的时间为32h,比优化前缩短约16h;最大菌体浓度为1.49×108CFU/ml,与预测值1.19×108CFU/ml接近,比优化前高近一个数量级。

Plackett-Burman design was used to evaluate importance of the selected fifteen internal factors to the growth of Getotrichum candidum and Aspergillus oryzae. Results showed that KCl, MgSO4, K2HPO4, NaNO3 and saccharose were the main factors affecting the growth of the multiple strains. In addition, the central composite design and response surface analysis were used to determine the optimal levels of the main factors. The optimized medium was determined as follows： saccharose 32.5 g/L, KCl 2.4 g/L, MgSO4 0.48 g/L, K2HPO4 1.5 g/L, NaNO3 4.0g/L and natural pH. Under these conditions, cell density of multiple strains can increase from 1.35 ×10^7 CFU/ml to 1.49×10^8 CFU/ml and time used to obtain maximal cell production decreases from 48 h to 32 h. The experimental data have validated the theoretical values.