柠檬酸钠对L-组氨酸发酵代谢流分布的影响

Effects of Sodium Citrate on Metabolic Flux Distributions of L-Histidine Production

目的:建立谷氨酸棒杆菌TL1105生物合成L-组氨酸的代谢网络模型,并进行代谢网络计量分析。方法:通过所构建的L-组氨酸代谢网络模型,利用MATLAB软件计算出添加柠檬酸钠和不添加柠檬酸钠发酵中后期代谢网络的代谢流分布。结果:在L-组氨酸分批发酵过程中,在发酵初期未添加柠檬酸钠的条件下流向戊糖磷酸途径(HMP)的代谢流为9.59,合成组氨酸的代谢流为8.91;在发酵初期添加2g/L柠檬酸钠的条件下流向HMP的代谢流为12.74,合成组氨酸的代谢流为9.61。结论:在发酵初期添加柠檬酸钠能够改变L-组氨酸生物合成途径的关键节点6-磷酸葡萄糖、丙酮酸及乙酰辅酶A的代谢流分布,保持糖酵解途径、三羧酸循环与HMP之间代谢流量平衡,有利于提高L-组氨酸生物合成途径的代谢流量,最终使流向组氨酸的代谢流增加了7.86%。

Objective： The metabolic flux balance model of L-histidine synthesis by Corynebacterium glutamicum TL1105 was established and the stoichiometric analysis of L-histidine biosynthesis was conducted. Methods： Based on this model, the practical metabolic flux distribution in the middle and late period with sodium citrate and without sodium citrate were determined with the linear program planted in MATLAB softwere. Results： The results show that the metabolic flux channeled to hexose monophosphate pathway （HMP） and L-histidine synthesis pathway is 9.59 and 8.91 respectively in the batch fermentation without the addition of sodium citrate and this metabolic flux becomes 12.74 and 9.61 respectively when sodium citrate（2.0 g/L） was added to the fermentation medium in the beginning. Conclusion： The addition of sodium citrate can change the metabolic flux distributions of the key nodes（glucose-6-phosphate, pyruvic acid, acetylcoenzyme A） and keep the metabolic flux balance among Embden-Meyerhof-Parnas pathway（EMP）, tricarboxylic acid cycle（TCA） and HMP, which strengthens the L-histidine biosynthesis. L-histidine biosynthesis inscreases 7.86% finally.