代谢工程改造大肠杆菌合成丙二酸

丙二酸是一种重要的有机二元羧酸，其应用价值遍及化工、医药、食品等领域。本文以大肠杆菌为底盘细胞，过表达了ppc、aspC、panD、pa0132、yneI和pyc基因，成功构建了丙二酸合成重组菌株大肠杆菌BL21(TPP)。该菌株在摇瓶发酵条件下，丙二酸产量达到0.61 g/L。在5 L发酵罐水平，采用间歇补料的方式丙二酸的积累量达3.32 g/L。本研究应用了融合蛋白技术，将ppc和aspC、pa0132和yneI分别进行融合表达，构建了工程菌BL21(SCR)。在摇瓶发酵水平，该菌株丙二酸的积累量达到了0.83 g/L，较出发菌株BL21(TPP)提高了36%。在5 L发酵罐中，工程菌BL21(SCR)的丙二酸产量最高达5.61 g/L，较出发菌株BL21(TPP)提高了69%。本研究实现了丙二酸在大肠杆菌中的生物合成，为构建丙二酸合成的细胞工厂提供了理论依据和技术基础，同时也对其他二元羧酸的生物合成具有启发和指导意义。

Metabolic engineering of Escherichia coli for production of malonic acid

Malonic acid is an important dicarboxylic acid, which can be widely used in the fields of chemical industry, medicine and food. In this study, a recombinant Escherichia coli strain BL21(TPP)was constructed to synthesize malonate through overexpressing six genes of ppc, aspC, panD, pa0132,yneI and pyc. Under shake flask fermentation conditons, strain BL21(TPP) produced 0.61 g/L malonic acid. In a 5 L fermentor, the production of malonic acid reached 3.32 g/L by using an intermittent feeding strategy. Next, a recombinant strain BL21(SCR) was constructed by fusional expression of ppc and aspC, as well as pa0132 and yneI, respectively. As a result, the production of malonic acid increased to 0.83 g/L at the shake flask level, which was a 36% increase over the starting strain BL21(TPP).Finally, the highest malonate production reached 5.61 g/L in a 5 L fermentor, which was a 69% increase over the starting strain BL21(TPP). Production of malonic acid by metabolically engineered E. coli provides a basis for further optimization, and may also serve as a reference for the biosynthesis of other dicarboxylic acids.