维生素C一菌一步发酵过程中醇糖酮氧化机制及其调控

维生素C是食品工业中重要的酸味剂和抗氧化剂，在食品工业中的应用比例占总生产量的85%以上。随着发酵工业的发展和几十年的工业实践，目前工业生产中采用的维生素C三菌二步发酵工艺存在的问题日益突出，如能耗水耗高、生产稳定性差、菌种选育困难等。采用一菌一步发酵工艺，将有望彻底解决上述问题，并为维生素C产业带来革命性提升。本研究基于前期获得的一株可以高度特异性转化D-山梨醇直接生成维生素C前体2-酮基-L-古龙酸的菌株，通过对醇/糖/酮高特异性不完全氧化、脱氢酶系底物通道效应、脱氢酶系关键辅因子的高效再生等的机制解析，系统强化维生素C前体合成过程，最终实现一菌一步高效发酵。本项目研究结果不仅能够实现特定产物的高效发酵生产，同时也将为食品微生物混菌发酵体系的解析与重构提供理论和方法学参考。一菌一步发酵法的实施，对保障中国作为维生素C技术领先大国、占领国际食品生物技术制高点，均具有重大的学术和应用价值。

Vitamin C is an important acidifying agent and antioxidant in the food industry. More than 85% of the vitamin C produced has been consumed by food industry. With the continuous development of fermentation industry and decades of industrial practice, the problems of three-bacteria-two-step fermentation process of vitamin C used in current industrial production are increasingly prominent, such as high energy consumption and water consumption, poor stability of production process, and difficulties in breeding strains. Using one-bacterium-one-step fermentation process, it is expected to solve the above problems thoroughly and bring about a revolutionary promotion to the vitamin C industry. In this project, based on a previous obtained strain that can achieve directly and highly specific conversion of D-sorbitol to 2-keto-L-gulonic acid, which is the precursor of vitamin C, mechanisms related to the high specificity incomplete oxidation of sugar/alcohol/ketone, substrate channel effect of dehydrogenases, efficient regeneration of the key cofactors of dehydrogenase system would be well demonstrated. Furthermore, the highly efficient one-bacterium-one-step fermentation process would be achieved based on the results. The results obtained in this project can not only achieve efficient fermentation of specific products, but also provide theoretical and methodological references for the analysis and reconstruction of mixed fermentation systems of food microorganisms. The implementation of one-bacterium-one-step fermentation is of great academic and practical value to ensure that China is a leading power in vitamin C technology and occupy the commanding heights of international food biotechnology.