生物素及膜偶联间歇透析发酵对黄色短杆菌生产L-亮氨酸的影响

Effects of biotin and membrane coupled intermittent dialysis fermentation on the production of L-leucine by Brevibacterium flavum

生物素作为微生物的生长因子,对生长速率、细胞膜通透性、代谢产物的生成等方面具有重要作用。为提高黄色短杆菌产L-亮氨酸产量,降低副产物生成,在30 L发酵罐水平研究了在培养基中添加20、50、80、120μg/L四种不同质量浓度生物素,对黄色短杆菌产L-亮氨酸的影响。结果表明:培养基中添加50μg/L生物素,黄色短杆菌发酵44 h,L-亮氨酸的产量最高,达到60 g/L,糖酸转化率为22%,副产物L-丙氨酸的质量浓度为8 g/L。在最适生物素浓度下,发酵36 h后,采用膜偶联间歇透析发酵工艺,发酵周期延长至56 h,L-亮氨酸的糖酸转化率为25%,较普通发酵工艺约提高13. 6%,副产物L-丙氨酸的浓度降低约71. 3%,L-亮氨酸的总产量提高了16. 7%。研究结果对提高糖利用率、降低副产物、提高生产效率等方面具有重要意义。

As a growth factor of microorganisms, biotin plays important roles in growth rate, cell membrane permeability, and metabolites production etc. In order to increase the yield of L -leucine produced by Brevibacterium flavum and reduce the formation of by-products, different concentrations of biotin (20, 50, 80, 120 μg/L) were added to the medium in a 30 L bioreactor. The results showed that the yield of L-leucine produced by B. flavum reached the highest (60g/L) in the medium that contained 50 μg/L biotin and fermented for 44 h. Moreover, the glucose conversion rate was 22% and the concentration of by-product L -alanine was 8g/L. At the optimal biotin concentration, the membrane coupled intermittent dialysis fermentation was used after 36 h fermentation, and the fermentation period was extended to 56 h. As a result, the glucose conversion rate reached 25%, which was about 13.6% higher than that of common fermentation process, and the concentration of L -alanine was about 71.3% lower. Furthermore, the production of L -leucine increased by 16.7%. Overall, the results are of great significance to improve glucose utilization, reduce by-products, and improve the production of L -leucine.