Department of Energy Science and Technology (DEST), Energy and Environment Fusion Technology Center (E2FTC), Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, Gyeonggi-do, 170-58, South Korea.
Division of Bioscience and Bioinformatics, Myongji University, Myongji-ro 116, Cheoin-gu, Yongin, Gyeonggi-do, 170-58, South Korea.
J Ind Microbiol Biotechnol. 2019 Feb;46(2):159-169. doi: 10.1007/s10295-018-2117-2. Epub 2018 Dec 15.
The non-conventional D-xylose metabolism called the Dahms pathway which only requires the expression of at least three enzymes to produce pyruvate and glycolaldehyde has been previously engineered in Escherichia coli. Strains that rely on this pathway exhibit lower growth rates which were initially attributed to the perturbed redox homeostasis as evidenced by the lower intracellular NADPH concentrations during exponential growth phase. NADPH-regenerating systems were then tested to restore the redox homeostasis. The membrane-bound pyridine nucleotide transhydrogenase, PntAB, was overexpressed and resulted to a significant increase in biomass and glycolic acid titer and yield. Furthermore, expression of PntAB in an optimized glycolic acid-producing strain improved the growth and product titer significantly. This work demonstrated that compensating for the NADPH demand can be achieved by overexpression of PntAB in E. coli strains assimilating D-xylose through the Dahms pathway. Consequently, increase in biomass accumulation and product concentration was also observed.
先前已经在大肠杆菌中构建了一种非传统的 D-木糖代谢途径，称为 Dahms 途径，该途径只需要至少表达三种酶即可产生丙酮酸和甘油醛。依赖该途径的菌株表现出较低的生长速率，最初归因于氧化还原稳态受到干扰，这可以从指数生长阶段细胞内 NADPH 浓度较低得到证明。然后测试了 NADPH 再生系统以恢复氧化还原稳态。过表达膜结合吡啶核苷酸转氢酶 PntAB，导致生物量和甘醇酸产量和得率显著增加。此外，在优化的生产甘醇酸的菌株中表达 PntAB 可显著提高生长和产物滴度。这项工作表明，通过在通过 Dahms 途径同化 D-木糖的大肠杆菌菌株中过表达 PntAB，可以满足 NADPH 的需求。因此，还观察到生物量积累和产物浓度的增加。
