Wu Wei-Bin, Guo Xiao-Lei, Zhang Ming-Liang, Huang Qing-Gen, Qi Feng, Huang Jian-Zhong
Engineering Research Center of Industrial Microbiology, Ministry of Education, Fujian Normal University, Fuzhou, People's Republic of China.
Biotechnol Appl Biochem. 2018 May;65(3):476-483. doi: 10.1002/bab.1605. Epub 2017 Sep 23.
l-Phenylalanine is an important amino acid that is widely used in the production of food flavors and pharmaceuticals. Generally, l-phenylalanine production by engineered Escherichia coli requires a high rate of oxygen supply. However, the coexpression of Vitreoscilla hemoglobin gene (vgb), driven bya tac promoter, with the genes encoding 3-deoxy-d-arabinoheptulosonate-7-phosphate synthetase (aroF) and feedback-resistant chorismate mutase/prephenate dehydratase (pheA ), led to increased productivity and decreased demand for aeration by E. coli CICC10245. Shake-flask studies showed that vgb-expressing strains displayed higher rates of oxygen uptake, and l-phenylalanine production under standard aeration conditions was increased. In the aerobic fermentation process, cell growth, l-phenylalanine production, and glucose consumption by the recombinant E. coli strain PAPV, which harbored aroF, pheA , and tac-vgb genes, were increased compared to that in the strain harboring only aroF and pheA (E. coli strain PAP), especially under oxygen-limited conditions. The vgb-expressing strain PAPV produced 21.9% more biomass and 16.6% more l-phenylalanine, while consuming only approximately 5% more glucose after 48 H of fermentation. This study demonstrates a method to enhance the l-phenylalanine production by E. coli using less intensive and thus more economical aeration conditions.
L-苯丙氨酸是一种重要的氨基酸，广泛应用于食品香料和药品的生产。一般来说，通过工程改造的大肠杆菌生产L-苯丙氨酸需要高氧供应率。然而，由tac启动子驱动的透明颤菌血红蛋白基因（vgb）与编码3-脱氧-D-阿拉伯庚酮糖酸-7-磷酸合成酶（aroF）和抗反馈分支酸变位酶/预苯酸脱水酶（pheA）的基因共表达，提高了大肠杆菌CICC10245的生产力并降低了通气需求。摇瓶研究表明，表达vgb的菌株显示出更高的氧气摄取率，并且在标准通气条件下L-苯丙氨酸的产量增加。在好氧发酵过程中，与仅含有aroF和pheA的菌株（大肠杆菌菌株PAP）相比，含有aroF、pheA和tac-vgb基因的重组大肠杆菌菌株PAPV的细胞生长、L-苯丙氨酸产量和葡萄糖消耗增加，特别是在氧气受限的条件下。表达vgb的菌株PAPV在发酵48小时后产生的生物量多21.9%，L-苯丙氨酸多16.6%，而葡萄糖消耗仅增加约5%。本研究展示了一种利用强度较低从而更经济的通气条件来提高大肠杆菌L-苯丙氨酸产量的方法。
