2-酮基-L-古龙酸一步发酵生产菌株发酵过程优化

Bioprocess optimization for the production of 2-keto-L-gulonic acid by a one-step fermentation strain

对1株可以一步发酵生产维生素C直接前体2-酮基-L-古龙酸（2-keto—L—gulonic acid，2-KLG）的氧化葡萄糖酸杆菌工程菌株（Gluconobacter oxydans—ss）的发酵条件进行优化，以提高其发酵效率。结合Box—Behnken实验和响应面法对其初始发酵培养基进行优化，得到优化的发酵培养基组成：山梨醇158．0g／L，酵母膏18．0g／L，初始pH5．0。采用该优化培养基在3L全自动发酵罐上进行发酵过程控制。在考察不同转速对2-KLG积累过程影响的基础上，进一步提出分阶段转速控制策略：即发酵前期（0～48h）转速控制在600r／min，48h至发酵结束转速控制在500r／min。应用该策略，2-KLG产量达到34．86g／L，生产强度为0．36g／（L·h），其分别比恒定转速发酵时2-KLG的最大产量提高24．01％和24．14％。

The fermentation conditions of Gluconobacter oxydans-ss, a one-step fermentation strain, were optimized to improve the production of 2-keto-L-gulonic acid （2-KLG） , which is the precursor of vitamin C. Box-Behnken design and response surface strategy were applied to optimize the initial medium. The optimal medium for G. oxydans-ss was composed of sorbitol 158.0 g/L and yeast extract 18.0 g/L, pH 5.0. Subsequently, a lab-scale experiment was carried out in 3 L fermentor with the optimal medium. The effect of different speeds （500,600,700 r/min） on 2-KLG production was investigated. A step-wise speed control strategy （0 -48 h, 600 r/rain; 48 h to the end, 500 r/rain） was introduced. With this strategy, 2-KLG yield （34. 86 g/L） and productivity （0.36 g/（L · h）） increased by 24.01% and 24.14% , respectively, compared to that without speed control.