L-苹果酸是一种安全无毒无害的食用有机酸，是继柠檬酸、乳酸之后的世界第三大酸味添加剂，在食品等行业具有重要作用。目前国内外文献对L-苹果酸的报道主要集中在酶转化和微生物发酵过程，对已知个体酶进行改造和调控的研究鲜有报道，而产氨短杆菌生产苹果酸过程的酶学基础及定向代谢调控未见报道。本项目将通过对产氨短杆菌代谢中的产物L-苹果酸及副产物琥珀酸酶体系及索酸酶和延胡索酸还原酶催化的桥梁反应进行调控，确定代谢流节点、方向、通量等，探讨酶体系的配比、底物选择机制、环境应答等因素对代谢分配的影响规律，对不同状态下各代谢路径的通量分布作出描述，更好利用细胞酶体系进行催化转化、代谢调节、能量传导和超分子组装，建立酶体系扰动代谢的调控模型。为微生物代谢功能的优化提供新技术手段，也为其他微生物的体内调节提供一个高效的平台，同时为生物法生产食品添加剂提供可借鉴的模板。

L-malic acid is a very important safe, nontoxic, harmless edible organic acid, following the citric acid, lactic acid as the world's third largest acid additives, which plays an important role in the food industry.The publiched leterature on the L-malic acid is mainly in the enzymatic conversion and microbial fermentation and few reports on confined to cloned or regulated individual enzyme while its enzymatic processes and metabolic orientation regulation researches were relatively weak. The project will study the influence of structure of the enzyme system, the mechanism of chiral selector and environmental response to the metabolic, add micro disturbance of the internal and external conditions and change the rate of the enzymatic reaction, then determine the metabolic flux node, direction and flow flux.Through the describing of the distribution of the different state metabolic flux path, we can make better use of the cellular enzyme system of metabolic regulation, energy conduction and supramolecular assembly,and then establish the enzyme systems disturbance model. It will provide new technologies for the optimization of microbial metabolism, an efficient platform for the in vivo regulation of other microorganisms, and a reference template for the biological production of food additives.