Abstract:

Aromatic amino acids (including L-tryptophan, L-phenylalanine and L-tyrosine) and their derivatives have been widely used in medicine, food, feed and chemical industry due to their specific physiological properties. The production of aromatic amino acids and their derivatives by recombinant microbial fermentation is an effective way to meet the increasing global demand. By combining metabolic engineering strategy with the developments of synthetic biology, systems biology and bioengineering, remarkable progress has been made in the strains modifications and improvements. However, the metabolic pathways for the synthesis of aromatic amino acids and their derivatives are long and their regulatory mechanisms are complicated, so it is very difficult to significantly improve the yield through simple metabolic pathway-modification. Therefore, many relevant modification methods have emerged in recent years, providing a good reference for overcoming the rate limit problem in the metabolic pathways. In this paper, we review and compare the recent mature technologies and strategies applied in the synthesis of aromatic amino acids and their derivatives, including the commonly used metabolic pathway modification strategies, such as increasing the supply of precursors, removing the feedback inhibition for key enzymes, eliminating the repression of repressor proteins, regulating the transport system and global metabolic network, the coupling of strain's growth and product's production and introducing exogenous related enzymes and so on. Various methods of strain construction are also included, such as the high-throughput screening based on biosensors and optimization of culture medium and culture conditions and so on. Finally, we also discuss the prospect of relevant cutting-edge technologies such as computer design of protein, computer de novo design of enzyme, computer design of metabolic pathway, alphafold algorithm for accurate prediction of protein structure and bifunctional enzyme, and the directed evolution technology for screening high yield strains such as the batch and continuation of the directed evolution.

Key words: aromatic amino acids, precursors, feedback inhibition, strain construction, aromatic amino acid derivatives

摘要：

芳香族氨基酸及其衍生物由于其特定的生理活性，已广泛应用于医药、食品、饲料和化工等行业。利用重组微生物发酵生产芳香族氨基酸及其衍生物是满足全球日益增长需求的有效途径。通过将代谢工程策略与合成生物学、系统生物学和生物工程的发展相结合，在菌株的改造及优化方面取得了显著的进展。然而，合成芳香族氨基酸及其衍生物的代谢途径长且调控机制复杂，通过简单的代谢途径改造难以大幅提高产量，因此，近年来出现了很多相关的改造方法，为克服代谢途径中的限速问题提供了很好的借鉴意义。本文回顾和比较了最近在芳香族氨基酸及其衍生物合成方面应用的成熟技术和策略，包括常用的代谢途径改造策略（如增加前体供给、解除关键酶和阻遏蛋白的反馈抑制和阻遏抑制、改造转运系统、全局调节系统）以及菌株生长与生产产品耦联和菌株构建方法（如基于生物传感器的高通量筛选以及对培养基和培养条件的优化等），未来相关前沿技术如计算机辅助途径酶改造技术和筛选高产菌株的定向进化技术将助力芳香族氨基酸及其衍生物高产菌株的构建。

关键词: 芳香族氨基酸, 前体, 反馈抑制, 菌株构建, 芳香族氨基酸衍生物