L-乳酸发酵培养基中氮源的优化

为减少L-乳酸发酵培养基中的酵母粉用量以降低生产成本,对培养基中的氮源进行了优化。通过单因素试验选择出玉米浆干粉作为与酵母粉进行优化的氮源。从响应面法的分析结果中得出,玉米浆在模型方程的一次和二次项上均比酵母粉显著而两者交互作用不显著,这表明玉米浆部分代替酵母粉是可行的;同时,响应面优化试验确定了两种氮源的最佳配比。当培养基中玉米浆的含量为32.23g/L,酵母粉的含量为3.17g/L时,乳酸的实际最大产量为103.71g/L,乳酸产量有5.3%的少许下降,而酵母粉的用量减少了84%。

Optimization of nitrogen source in medium of L-lactic acid fermentation

In this work,the nitrogen source in the medium of L-lactic acid fermentation was optimized to reduce the amount of yeast extract(YE) which would help cut down the production cost.Corn steep liquor(CSL) powder was selected as the nitrogen source to optimize with YE through one-factor-at-a-time method.Response surface methodology(RSM) and central composite design were successfully applied to evaluate the effect of CSL and YE based on the second-order polynomial equation.The result showed that the linear effect and the squared effect of CSL were more significant than those of YE while the interaction effect between them was insignificant which inferred that it was feasible for CSL to partly substitute YE.In addition,the optimum composition of these two kinds of nitrogen source was determined by RSM.The maximum L-lactic acid production of 103.71g/L was obtained when the optimum concentrations of CSL and YE were 32.23g/L and 3.17g/L,respectively.Comparing to the L-lactic acid fermentation using YE as the sole nitrogen source,the production of L-lactic acid was reduced by 5.3% while the amount of YE was decreased by 84% in the medium.