摘要
应用代谢流分析方法研究了磷酸盐对Escherichia coli TRJH L-色氨酸发酵中后期胞内代谢流分布的影响.结果表明:在发酵中后期添加4.0,g/L,KH2PO4时,与不添加KH2PO4相比,L-色氨酸合成的代谢流增加了19.3%,而副产物Lac、HAc和Ala的代谢流仅增加了6.0%、7.8%和6.8%.与添加8.0,g/L,KH2PO4比较,副产物代谢流的增量明显减少,说明磷酸盐的过量添加会使EMP途径代谢流量超过TCA及L-色氨酸合成支路的代谢能力,从而导致副产物的生成增加,L-色氨酸生物合成的转化率相对降低.因此,在L-色氨酸发酵过程中应该严格控制磷酸盐的用量.
In order to study the effects of phosphate on the metabolic flux distributions in Escherichia coli TRJH fermentation during the middle and late period,the metabolic flux analysis of the L-tryptophan biosynthesis at pseudo steady state was conducted. The results show that the metabolic flux with 4.0 g/L addition of KH2PO4 channeled to the L-tryptophan synthesis pathway increased by 19.3% compared to that without KH2PO4,while the metabolic flux of by-product including Lae,HAc and Ala increased by only 6.0%, 7.8% and 6.8%. The incremental metabolic flux of by-product decreased significantly compared to 8.0 g/L addition of KH2PO4. The excess of phosphate made the metabolic flux channeled to EMP pathway exceed the requirements of TCA Cycle and L-tryptophan biosynthesis,which leading to the increasing of by-products and relatively decreasing of L-tryptophan biosynthesis rate. Therefore,the amount of phosphate should be strictly controlled in the L- tryptophan fermentation process.
出处
《天津科技大学学报》
CAS
2009年第5期10-13,26,共5页
Journal of Tianjin University of Science & Technology
基金
国家"十一五"科技支撑计划项目(2008BAI63B01)
国家科技重大专项课题(2008ZX09401-05)
关键词
L-色氨酸
线性规划
代谢流分析
磷酸盐
L-tryptophan
linear program
metabolic flux analysis
phosphate
