分阶段pH调控提高2-酮基-L-古龙酸生产

Enhancement of 2-keto-L-gulonic acid production using three-stage pH control strategy

摘要:

为了提高酮古龙酸菌Ketogulonicigenium vulgare和巨大芽胞杆菌Bacillus megaterium生产2-酮基-L-古龙酸(2-KLG) 的生产效率，分析了pH对K. vulgare和B. megaterium生长和产酸的影响，发现K. vulgare和B. megaterium的最适生长pH值分别为6.0和8.0，但是K. vulgare的糖酸转化活力在pH 7.0时达到最大值，因此提出了三阶段pH控制策略 (第一阶段：0~8 h，pH 8.0；第二阶段：8~20 h，pH 6.

Abstract:

The aim of this study was to improve the 2-keto-L-gulonic acid (2-KLG) production efficiency by Ketogulonicigenium vulgare and Bacillus megaterium by using multi-stage pH control strategy. The effect of pH on the cell growths and 2-KLG production showed that the optimum pH for K. vulgare and B. megaterium cell growth were 6.0 and 8.0, respectively, while the optimum pH for 2-KLG production was 7.0. Based on the above results, we developed a three-stage pH control strategy: the pH was kept at 8.0 during the first 8 h, then decreased to 6.0 for the following 12 h, and maintained at 7.0 to the end of fermentation. With this strategy, the titer, productivity of 2-KLG and L-sorbose consumption rate were achieved at 77.3 g/L, 1.38 g/(L·h) and 1.42 g/(L·h), respectively, which were 9.7%, 33.2% and 25.7% higher than the corresponding values of the single pH (pH 7.0) control model.