【摘要】 分析黄色短杆菌(Brevibacterium flavum)中L–异亮氨酸生物合成途径得知,添加柠檬酸钠利于L–异亮氨酸发酵.通过考察柠檬酸添加量对副产物含量、菌体生物量、菌体比生长速率及L–异亮氨酸产量的影响,得出柠檬酸钠的最适添加量为2.0 g/L.应用代谢流分析方法研究了柠檬酸钠对L–异亮氨酸发酵中后期细胞内代谢流分布的影响.结果表明,在初始发酵培养基中添加2.0 g/L柠檬酸钠后,合成副产物的代谢流量明显减少,EMP途径代谢流从63.34减弱至46.54,而L–异亮氨酸的生物合成代谢流增长至23.28,较添加前提高了5.91%,且产量提高了7.87%.因此,发酵过程中添加柠檬酸钠可有效减少副产物的生成,提高L–异亮氨酸生物合成途径的代谢流量.更多还原

【Abstract】 The biosynthesis metabolism pathway of L-isoleucine in Brevibacterium flavum was analyzed,and the addition of sodium citrate was beneficial to L-isoleucine fermentation.The effects of sodium citrate on concentration of byproduct,biomass,specific growth rate and yield of L-isoleucine were studied.The optimal addition concentration of sodium citrate was 2.0 g/L.In order to study the effects of sodium citrate on the metabolic flux distributions in Brevibacterium flavum fer-mentation during the middle and late period,the metabolic flux analysis of the L-isoleucine production at pseudo steady state was conducted.The results show that the metabolic flux channeled to byproducts is decreased obviously when sodium cit-rate(2.0 g/L)is added to the fermentation medium.Moreover,with the addition of sodium citrate,the flux channeled to EMP decreases from 63.34 to 46.54.At the same time,the metabolic flux channeled to the L-isoleucine synthesis pathway in-creases 5.91% and becomes 23.28,and the yield of L-isoleucine increases 7.87%.All of these show that the addition of so-dium citrate leads to the decrease of byproducts formation and strengthens the L-isoleucine biosynthesis.更多还原