The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800# Lihu Road, Wuxi 214122, China.
Int J Mol Sci. 2023 Jul 24;24(14):11866. doi: 10.3390/ijms241411866.
L-tryptophan (L-trp), produced through bio-manufacturing, is widely used in the pharmaceutical and food industries. Based on the previously developed L-trp-producing strain, this study significantly improved the titer and yield of L-trp, through metabolic engineering of the shikimate pathway and the L-tryptophan branch. First, the rate-limiting steps in the shikimate pathway were investigated and deciphered, revealing that the combined overexpression of the genes and increased L-trp production. Then, L-trp synthesis was further enhanced at the shaking flask level by improving the intracellular availability of L-glutamine (L-gln) and L-serine (L-ser). In addition, the transport system and the competing pathway of L-trp were also modified, indicating that elimination of the gene contributed to the extracellular accumulation of L-trp. Through optimizing formulas, the robustness and production efficiency of engineered strains were enhanced at the level of the 30 L fermenter. After 42 h of fed-batch fermentation, the resultant strain produced 53.65 g/L of L-trp, with a yield of 0.238 g/g glucose. In this study, the high-efficiency L-trp-producing strains were created in order to establish a basis for further development of more strains for the production of other highly valuable aromatic compounds or their derivatives.
L-色氨酸（L-Trp）通过生物制造生产，广泛应用于医药和食品行业。本研究基于先前开发的 L-Trp 生产菌株，通过对莽草酸途径和 L-色氨酸分支的代谢工程，显著提高了 L-Trp 的产量和效价。首先，研究了莽草酸途径中的限速步骤，并对其进行了破译，结果表明，同时过表达基因 和 可以增加 L-Trp 的产量。然后，通过提高细胞内 L-谷氨酰胺（L-Gln）和 L-丝氨酸（L-Ser）的可用性，在摇瓶水平进一步增强 L-Trp 的合成。此外，还对 L-Trp 的转运系统和竞争途径进行了修饰，表明消除 基因有助于 L-Trp 的胞外积累。通过优化配方，在 30 L 发酵罐水平上提高了工程菌株的稳健性和生产效率。经过 42 h 的分批补料发酵，得到的菌株生产了 53.65 g/L 的 L-Trp，葡萄糖得率为 0.238 g/g。在本研究中，构建了高效 L-Trp 生产菌株，为进一步开发生产其他高价值芳香族化合物或其衍生物的更多菌株奠定了基础。
