Ding Shuang, Chen Xiulai, Gao Cong, Song Wei, Wu Jing, Wei Wanqing, Liu Jia, Liu Liming
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, Jiangsu, China.
International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, Jiangsu, China.
Sheng Wu Gong Cheng Xue Bao. 2023 Jun 25;39(6):2359-2374. doi: 10.13345/j.cjb.221005.
As an essential amino acid, l-tryptophan is widely used in food, feed and medicine sectors. Nowadays, microbial l-tryptophan production suffers from low productivity and yield. Here we construct a chassis . TRP3 producing 11.80 g/L l-tryptophan, which was generated by knocking out the l-tryptophan operon repressor protein () and the l-tryptophan attenuator (), and introducing the feedback-resistant mutant . On this basis, the l-tryptophan biosynthesis pathway was divided into three modules, including the central metabolic pathway module, the shikimic acid pathway to chorismate module and the chorismate to tryptophan module. Then we used promoter engineering approach to balance the three modules and obtained an engineered . TRP9. After fed-batch cultures in a 5 L fermentor, tryptophan titer reached to 36.08 g/L, with a yield of 18.55%, which reached 81.7% of the maximum theoretical yield. The tryptophan producing strain with high yield laid a good foundation for large-scale production of tryptophan.
作为一种必需氨基酸，L-色氨酸广泛应用于食品、饲料和医药领域。目前，微生物法生产L-色氨酸存在生产率和产量较低的问题。在此，我们构建了一株底盘菌株TRP3，通过敲除L-色氨酸操纵子阻遏蛋白（）和L-色氨酸衰减子（），并引入反馈抗性突变体，该菌株可产生11.80 g/L的L-色氨酸。在此基础上，将L-色氨酸生物合成途径分为三个模块，包括中心代谢途径模块、莽草酸途径至分支酸模块和分支酸至色氨酸模块。然后，我们采用启动子工程方法平衡这三个模块，获得了工程菌株TRP9。在5 L发酵罐中进行补料分批培养后，色氨酸产量达到36.08 g/L，产率为18.55%，达到最大理论产率的8 l.7%。高产色氨酸生产菌株为色氨酸的大规模生产奠定了良好基础。
