CAS Key Laboratory of Microbial Physiological and Metabolic Engineering and State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China.
National Engineering Research Center of Industrial Microbiology and Fermentation Technology; College of Life Sciences, Fujian Normal University, Fuzhou, Fujian 350108, China.
Metab Eng. 2017 Nov;44:143-149. doi: 10.1016/j.ymben.2017.09.013. Epub 2017 Sep 22.
The efficiency of biocatalysis is often affected by an insufficient supply and regeneration of cofactors and redox equivalents. To alleviate this shortcoming, a cofactor self-sufficient system was developed for enhanced production of 2-phenylethanol (2-PE) in E. coli. A "bridge" between the amino acid and its corresponding alcohol was designed in the system using glutamate dehydrogenase. By coupling glutamate dehydrogenase with transaminase and alcohol dehydrogenase, the cosubstrate (2-oxoglutarate) and redox equivalents (NAD(P)H) were regenerated simultaneously, so that no external cofactor or redox source was required. Thus, a cofactor self-sufficient system was developed, which improved the biocatalyst efficiency 3.8-fold. The ammonium generated in this process was removed using zeolite, which further improved the biosynthetic efficiency and resulted in a cleaner system. To the best of our knowledge, this system yielded the highest titer of 2-PE ever obtained in E. coli. Additionally, the wider applicability of this self-sufficient strategy was demonstrated in the production of D-phenyllactic acid. This study thus offers a new method to resolve the cofactor/redox imbalance problem and demonstrates the feasibility of the cofactor self-sufficient strategy for enhanced production of diverse chemicals.
生物催化的效率通常受到辅助因子和氧化还原当量供应和再生不足的影响。为了缓解这一缺点，开发了一种辅酶自给系统，以提高大肠杆菌中 2-苯乙醇（2-PE）的产量。该系统使用谷氨酸脱氢酶在氨基酸与其相应的醇之间设计了“桥梁”。通过将谷氨酸脱氢酶与转氨酶和醇脱氢酶偶联，同时再生辅助因子（2-氧代戊二酸）和氧化还原当量（NAD（P）H），因此不需要外部辅助因子或氧化还原源。因此，开发了一种辅酶自给系统，将生物催化剂效率提高了 3.8 倍。该过程中生成的铵通过沸石去除，这进一步提高了生物合成效率，并使系统更加清洁。据我们所知，该系统在大肠杆菌中获得了迄今为止最高的 2-PE 产量。此外，该自给自足策略的更广泛适用性在 D-苯乳酸的生产中得到了证明。因此，本研究提供了一种解决辅酶/氧化还原失衡问题的新方法，并证明了辅酶自给策略在增强多种化学品生产中的可行性。
