| Autor: |
Zhang Y; School of Life Sciences, Guangzhou University, 230 Wai Huan Xi Road, Guangzhou 510006, Guangdong, P. R. China.; School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, Jiangsu, P. R. China., Zhang G; School of Life Sciences, Guangzhou University, 230 Wai Huan Xi Road, Guangzhou 510006, Guangdong, P. R. China.; School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, Jiangsu, P. R. China., Zhang H; School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, Jiangsu, P. R. China., Tian Y; School of Life Sciences, Guangzhou University, 230 Wai Huan Xi Road, Guangzhou 510006, Guangdong, P. R. China., Li J; School of Life Sciences, Guangzhou University, 230 Wai Huan Xi Road, Guangzhou 510006, Guangdong, P. R. China., Yun J; School of Life Sciences, Guangzhou University, 230 Wai Huan Xi Road, Guangzhou 510006, Guangdong, P. R. China., Zabed HM; School of Life Sciences, Guangzhou University, 230 Wai Huan Xi Road, Guangzhou 510006, Guangdong, P. R. China., Qi X; School of Life Sciences, Guangzhou University, 230 Wai Huan Xi Road, Guangzhou 510006, Guangdong, P. R. China.; School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, Jiangsu, P. R. China. |
| Abstrakt: |
β-Alanine, a valuable β-type amino acid, is experiencing increased demand due to its multifaceted applications in food flavoring, nutritional supplements, pharmaceuticals, and the chemical industry. Nevertheless, the sustainable biosynthesis of β-alanine currently faces challenges due to the scarcity of robust strains, attributed to the complexities of modulating multiple genes and the inherent physiological constraints. Here, systems metabolic engineering was implemented in Escherichia coli to overcome these limitations. First, an efficient l-aspartate-α-decarboxylase (ADC) was recruited for β-alanine biosynthesis. To conserve phosphoenolpyruvate flux, we subsequently modified the endogenous glucose assimilation system by inactivating the phosphotransferase system (PTS) and introducing an alternative non-PTS system, which increased β-alanine production to 1.70 g/L. The supply of key precursors, oxaloacetate and l-aspartate, was synergistically improved through comprehensive modulation, including strengthening main flux and blocking bypass metabolism, which significantly increased the β-alanine titer to 3.43 g/L. Next, the expression of ADC was optimized by promoter and untranslated region (UTR) engineering. Further transport engineering, which involved disrupting β-alanine importer CycA and heterologously expressing β-alanine exporter NCgI0580, improved β-alanine production to 8.48 g/L. Additionally, corn steep liquor was used to develop a cost-effective medium. The final strain produced 74.03 g/L β-alanine with a yield of 0.57 mol/mol glucose during fed-batch fermentation. |
