柠檬酸钠对L-谷氨酸发酵代谢流迁移的影响

Effects of Sodium Citrate on Metabolic Flux Transfer of L-glutamic Acid Fermentation

为更全面深入地理解细胞内谷氨酸代谢的调控机制,以黄色短杆菌GDK-9为供试菌株,应用MATLAB软件和代谢流分析方法,定量研究了添加柠檬酸钠后L-谷氨酸发酵中后期胞内的代谢流迁移.在L-谷氨酸发酵中后期添加3.0 g/L柠檬酸钠后,合成副产物L-丙氨酸和乳酸的代谢流量明显减少,分别降低了18.7%和27.4%,EMP途径和乙醛酸循环的代谢流分别减少了0.88和2.12,HMP途径的代谢流增加了0.88,而L-谷氨酸生物合成的代谢流从73.59增长至76.47,较未添加前提高了3.9%.添加柠檬酸钠能使关键节点发生代谢流迁移,提高L-谷氨酸合成中心代谢途径的代谢流量.

In order to understand the regulate mechanism of L-glutamic acid metabolism,the metabolic flux transfer during the middle and late period of fermentation with the addition of sodium citrate was studied using MATLAB software with Brevibacterium flavum GDK-9 as the test strain. When 3.0 g/L sodium citrate was added to the fermentation medium,the formation of byproducts,such as L-ala and Lac,decreased by 18.7% and 27.4%,respectively. At the same time,the flux channeled to EMP and glyoxyl circle decreased by 0.88 and 2.12,respectively,however,the flux channeled to HMP increased by 0.88. The metabolic flux channeled to the L-glutamic acid synthesis pathway increased by 3.9% （from 73.59 to 76.47）. All of these showed that the addition of sodium citrate could change the metabolic flux distributions of the key nodes and strengthen the L-glutamic acid biosynthesis.