School of Life Sciences, Guangzhou University, 230 Wai Huan Xi Road, Guangzhou 510006, Guangdong, PR China; School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, Jiangsu, PR China.
School of Life Sciences, Guangzhou University, 230 Wai Huan Xi Road, Guangzhou 510006, Guangdong, PR China.
Bioresour Technol. 2023 Dec;389:129822. doi: 10.1016/j.biortech.2023.129822. Epub 2023 Oct 5.
3-Hydroxypropionic acid (3-HP) is a top value-added chemical with multifaceted application in chemical, material, and food field. However, limited availability of robust strains and elevated fermentation costs currently impose constraints on sustainable biosynthesis of 3-HP. Herein, transporter engineering, metabolic dynamic modulation, and enzyme engineering were combined to address above limitations. First, a glucose-utilizing 3-HP biosynthetic pathway was constructed in Escherichia coli, followed by recruiting alternative glucose transport system to overcome center metabolism overflow. Next, the Cra (a transcription factor)-dependent switch was applied to autonomously fine-tune carbon flux, which alleviated growth retardation and improved the 3-HP production. Subsequently, inactivation of glycerol facilitator (GlpF) increased intracellular glycerol levels and boosted 3-HP biosynthesis, but caused toxic intermediate 3-hydroxypropionaldehyde (3-HPA) accumulation. Furthermore, semi-rational design of aldehyde dehydrogenase (YdcW) increased its activity and eliminated 3-HPA accumulation. Finally, fed-batch fermentation of the final strain resulted in 52.73 g/L 3-HP, with a yield of 0.59 mol/mol glucose.
3-羟基丙酸（3-HP）是一种高附加值的化学品，在化学、材料和食品领域具有多方面的应用。然而，目前强大菌株的有限可用性和高昂的发酵成本限制了 3-HP 的可持续生物合成。在此，通过结合转运蛋白工程、代谢动态调节和酶工程来解决上述限制。首先，在大肠杆菌中构建了利用葡萄糖的 3-HP 生物合成途径，然后招募替代的葡萄糖运输系统来克服中心代谢物溢出。接下来，应用依赖于 Cra（转录因子）的开关来自主微调碳通量，从而缓解生长迟缓并提高 3-HP 的产量。随后，甘油促进剂（GlpF）的失活增加了细胞内甘油水平，促进了 3-HP 的生物合成，但导致有毒中间产物 3-羟基丙醛（3-HPA）的积累。此外，醛脱氢酶（YdcW）的半理性设计增加了其活性并消除了 3-HPA 的积累。最后，对最终菌株进行分批补料发酵，得到 52.73 g/L 的 3-HP，葡萄糖得率为 0.59 mol/mol。
