异亮氨酸产生菌推理选育思想

分析黄色短杆菌生物合成异亮氨酸的调节控制过程,结果表明,选育异亮氨酸产生菌,首先应考虑活化PC、AK、HD、TD、AHAS这五个关键酶,并减弱由PK、CS、AD、PS、HT引起的五条分支代谢强度,来强化生物合成异亮酸氨的主代谢流。根据这一思想,以Brevibacterium flavum AS111为出发菌株,利用IABS模型有目的地活化PC、HD和AHAS等酶,筛得23-10变株,产酸率可达20mg/ml以上,25代后产酸能力毫不下降。

RATI0NAL SELECTION OF L-ISOLEUCINE PRODUCER

To enhance the main pathway of isoleucine biosynthesis, its five key enzymes (PD,AK,HD,TD、and AHAS) should be activated and its five branch pathways (induced by the enzymes of PK, CS, AD, PS, and HT) should be weaken in the course of selecting isoleucine producer. A mutan, 23--10, which produced more than 20mg/ml isoleucine, was selected by IABS model with activated PC,HD and AHAS,etc.,its productivity did not decrease after 25 generations.