α-酮戊二酸对L-羟脯氨酸产量的影响

Effect of α-ketoglutarate on the yield of L-hydroxyproline

微生物合成L-羟脯氨酸时需要α-酮戊二酸的参与,而细胞内α-酮戊二酸的含量有限,限制了L-羟脯氨酸的高效合成。因此该实验通过在L-羟脯氨酸发酵过程中外源添加α-酮戊二酸,来考察α-酮戊二酸对发酵菌体生长、L-羟脯氨酸产量、糖酸转化率和代谢流的影响。结果表明,α-酮戊二酸对菌体生长有一定的抑制作用,但在一定浓度范围内,外源添加α-酮戊二酸能有效提高L-羟脯氨酸的产量和糖酸转化率,当随糖流加5 g/L(初始发酵液)α-酮戊二酸时,L-羟脯氨酸产量能够达到最大值62.14 g/L,糖酸转化率为22.37%,与不添加α-酮戊二酸相比,分别提高了47.85%和13.04%,同时,L-羟脯氨酸的合成代谢流提高了11.98%,副产物乙酸合成代谢流减少了29.42%。

The synthesis of L-hydroxyproline by microorganisms requires the participation of α-ketoglutarate, and the limited content of α-ketoglutarate in cells limits the efficient synthesis of L-hydroxyproline. Therefore, in this study, α-ketoglutarate was exogenously added during L-hydroxyproline fermentation to study the effect of α-ketoglutarate on cell growth, L-hydroxyproline production, glucose to acid conversion ratio and metabolic flux. The results showed that the cell growth was inhibited by α-ketoglutarate to a certain extent. The production of L-hydroxyproline and the glucose to acid conversion ratio could be effectively increased by the addition of α-ketoglutarate within a certain concentration range. When α-ketoglutarate was added along with glucose 5 g/L （relative to the initial volume of fermentation broth）, the highest production of L-hydroxyproline was 62.14 g/L, and the glucose to acid conversion ratio was 22.37%. Compared with the fermentation without extra α-ketoglutarate, the L-hydroxyproline production and glucose to acid conversion ratio increased by 47.85% and 13.04%, respectively. At the same time, the metabolic flux of L-hydroxyproline increased by 11.98% and the byproduct acetic acid metabolic flux decreased by 29.42%.