不同中和剂对米根霉发酵产L-乳酸的影响

Effect of Different Neutralizers on L-Lactic Acid Production by Rhizopus oryzae

在米根霉发酵产L-乳酸过程中,采用CaCO3作为中和剂会造成下游分离过程中膜堵塞和环保压力,因此以NH3·H2O和NaOH替代CaCO3作中和剂,对米根霉发酵产L-乳酸的工艺条件和发酵动力学进行研究。结果表明:添加CaCO3后L-乳酸产量平均提高7.3倍;NaOH、NH3·H2O作为中和剂的最佳浓度及质量分数分别为10mol/L、25%,以该条件进行发酵72h得菌丝体小球直径分别为0.2～1.2mm和1.2～2.2mm,残糖含量分别为2.58g/L和1.37g/L,L-乳酸产量分别为74.34g/L和80.61g/L。

Calcium carbonate added as the neutralizer during Rhizopus oryzae fermentation for L-lactic acid production would cause membrane fouling and environmental pressure during the downstream separation. As a consequence, ammonia and sodium hydroxide were separately used as a substitute for calcium carbonate in this study, and the fermentation conditions for L-lactic acid production and the fermentation kinetics were dealt with. Added calcium carbonate during during Rhizopus oryzae fermentation resulted in an average 7.3-fold increase in L-lactic acid production. The optimal concentrations of added ammonia and sodium hydroxide were 10 mol/L and 25%, respectively. Mycelial pellets in diameter ranges between 0.2 mm and 1.2 mm and between 1.2 mm and 2.2 mm were formed after 72 h fermentation under these concentration conditions, and the residual sugar amounts were 2.58 g/L and 1.37 g/L and the L-lactic acid concentrations in the fermentation broths were 74.34 g/L and 80.61 g/L, respectively.