Department of Pharmaceutical Engineering, College of Health Science, Sangji University, Sangjidae-gil 83, Wonju-si, Gangwon-do 220-702, Korea.
J Ind Microbiol Biotechnol. 2012 Dec;39(12):1869-74. doi: 10.1007/s10295-012-1197-7. Epub 2012 Sep 18.
With the purpose of generating a microbial strain for L-ornithine production in Corynebacterium glutamicum, genes involved in the central carbon metabolism were inactivated so as to modulate the intracellular level of NADPH, and to evaluate their effects on L-ornithine production in C. glutamicum. Upon inactivation of the 6-phosphoglucoisomerase gene (pgi) in a C. glutamicum strain, the concomitant increase in intracellular NADPH concentrations from 2.55 to 5.75 mmol g⁻¹ (dry cell weight) was accompanied by reduced growth rate and L-ornithine production, suggesting that L-ornithine production is not solely limited by NADPH availability. In contrast, inactivation of the gluconate kinase gene (gntK) led to a 51.8 % increase in intracellular NADPH concentration, which resulted in a 49.9 % increase in L-ornithine production. These results indicate that excess NADPH is not necessarily rate-limiting, but is required for increased L-ornithine production in C. glutamicum.
为了在谷氨酸棒杆菌中生成用于 L-鸟氨酸生产的微生物菌株，我们使参与中心碳代谢的基因失活，从而调节细胞内 NADPH 的水平，并评估它们对谷氨酸棒杆菌中 L-鸟氨酸生产的影响。在谷氨酸棒杆菌菌株中失活 6-磷酸葡萄糖异构酶基因 (pgi) 后，细胞内 NADPH 浓度从 2.55 mmol/g（干细胞重量）增加到 5.75 mmol/g，同时生长速率和 L-鸟氨酸产量降低，这表明 L-鸟氨酸的生产不仅受到 NADPH 供应的限制。相比之下，失活葡萄糖酸激酶基因 (gntK) 导致细胞内 NADPH 浓度增加 51.8%，使 L-鸟氨酸产量增加 49.9%。这些结果表明，过量的 NADPH 不一定是限速的，但对于谷氨酸棒杆菌中 L-鸟氨酸产量的增加是必需的。
