为提高ε-聚赖氨酸(ε-PL)合成能力,考察了柠檬酸对Streptomyces sp.M-Z18菌体生长和ε-PL合成的影响。研究发现,柠檬酸作为辅助能量物质,对ε-PL发酵过程影响显著。通过对柠檬酸添加时间、添加量和pH值的优化,确定了最佳柠檬酸添加方式,结合补料-分批发酵工艺,显著提高了ε-PL的产量。实验结果表明,在5L发酵罐中,维持pH为3.8,初始柠檬酸添加量为20 g/L时,分批发酵ε-PL的产量达到9.50 g/L,产率达到4.40 g/(L.d),较未添加柠檬酸发酵分别提高了46.4%和48.1%。采用添加柠檬酸的补料-分批发酵工艺,发酵168 h后ε-PL的产量达到22.89 g/L,是分批发酵的2.41倍。
The synthesis of ε-PL was performed by adding citric acid as auxiliary energy material.The results showed that contribution of citric acid to the fermentation of ε-PL was obvious.The optimum dose,addition time of citric acid and batch fermentations at various pH values were studied.Under the optimized condition,pH 3.8 and 20 g/L citric acid,the production of ε-PL reached 9.50 g/L and the productivity of ε-PL was 4.40 g/(L·d),it was enhanced by 46.4% and 48.1%,respectively,in contrast with original batch fermentation strategy.Moreover,the fed-batch production of ε-PL reached 22.89 g/L,2.41-fold of that in batch fermentation.
