Zhou Hai-Yan, Wu Wang-Jie, Xu Yue-Ying, Zhou Bin, Niu Kun, Liu Zhi-Qiang, Zheng Yu-Guo
Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China.
Engineering Research Center of Bioconversion and Biopurification, Ministry of Education, Zhejiang University of Technology, Hangzhou, China.
Front Bioeng Biotechnol. 2020 Apr 24;8:300. doi: 10.3389/fbioe.2020.00300. eCollection 2020.
L-Methionine (L-Met) is a sulfur-containing amino acid, which is one of the eight essential amino acids to human body. In this work, the fermentative production of L-Met with genetically engineered W3110-BL in a 5-L fermentor was enhanced through supplement of Ca into the fermentation medium. With the addition of 30 g/L calcium carbonate (CaCO), the titer of L-Met and yield against glucose reached 1.48 g/L and 0.09 mol/mol glucose, 57.45% higher than those of the control, respectively. The flux balance analysis (FBA) revealed that addition of CaCO strengthened the tricarboxylic acid cycle and increased the intracellular ATP concentration by 39.28%. The re-distribution of carbon, ATP, and cofactors flux may collaborate to improve L-Met biosynthesis with W3110-BL. The regulation of citrate synthase and oxidative phosphorylation pathway was proposed to be important for overproduction of L-Met. These foundations provide helpful reference in the following metabolic modification or fermentation control for further improvement of L-Met biosynthesis.
L-甲硫氨酸（L-Met）是一种含硫氨基酸，是人体必需的八种氨基酸之一。在本研究中，通过向发酵培养基中添加钙，在5升发酵罐中利用基因工程菌W3110-BL提高了L-甲硫氨酸的发酵产量。添加30 g/L碳酸钙（CaCO₃）后，L-甲硫氨酸的产量和对葡萄糖的产率分别达到1.48 g/L和0.09 mol/mol葡萄糖，分别比对照提高了57.45%。通量平衡分析（FBA）表明，添加CaCO₃增强了三羧酸循环，并使细胞内ATP浓度提高了39.28%。碳、ATP和辅因子通量的重新分配可能共同作用，以提高W3110-BL合成L-甲硫氨酸的能力。柠檬酸合酶和氧化磷酸化途径的调控被认为对L-甲硫氨酸的过量生产很重要。这些基础为后续的代谢改造或发酵控制提供了有益的参考，以进一步提高L-甲硫氨酸的生物合成。
