细胞生长和非生长相结合的拟干酪乳杆菌高效生产L-乳酸研究

Combination of Cell Growth Dependent and Independent Modes for Efficient L-Lactic Acid Production by Lactobacillus paracasei

本研究以拟干酪乳杆菌发酵生产L-乳酸为研究对象,通过对最适初始葡萄糖浓度以及稳定期静息细胞的代谢能力进行研究,开发了基于细胞生长和非生长相关组合的高细胞密度L-乳酸生产策略。研究结果表明,140 g/L初始葡萄糖浓度下,细胞能够快速生长而且将葡萄糖完全耗尽生产L-乳酸。此外,在发酵结束后6~7 h之内,细胞仍然能够维持非常高的代谢活性。最后,在此基础上开发的高细胞密度生产策略,能够使细胞在正常批发酵结束后高密度发酵阶段的产率较常规发酵阶段提升1.4倍,而且L-乳酸转化率也明显提升,达到0.985 g/g。本研究通过过程策略能够有效延长细胞高速率生产L-乳酸的周期,从而提升L-乳酸生产效率,同时也在一定程度上能够有效缩短发酵过程所需的辅助时间,包括种子制备和细胞生长,因此有望应用于工业乳酸的高效生产。

In this study,on the basis of L-lactic acid production by Lactobacillus paracasei,a high cell density strategy with the combination of cell growth dependent and independent modes was developed through investigating the optimal initial glucose concentration and the metabolic capacity of resting cells.The results indicated that the cells grew well under 140 g/L of initial glucose concentration,and all the glucose could be rapidly exhausted to produce L-lactic acid.Moreover,the cells could still maintain high metabolic activity within 6~7 h after the end of fermentation.Finally,based on the above results,the L-lactic acid productivity of high cell density phase was enhanced by 1.4-fold compared with that of normal batch fermentation,and the L-lactic acid yield was also improved significantly to 0.985 g/g.This study extended the highly efficient production period so as to improve the production efficiency of L-lactic acid.Otherwise,the auxiliary time required in the fermentation process could be effectively reduced,including seed preparation and cell growth.Thus,it would be potentially applied for future industrial lactic acid production.