Cofactor Engineering for Enhanced Production of Diols by Klebsiella pneumoniae From Co-Substrate

Diols, such as 1,3-propanediol (1,3-PDO) and 2,3-butanediol (2,3-BDO), have several promising properties for many synthetic reactions. Here, the cofactor engineering strategy, including the construction of Entner-Doudoroff pathway and transhydrogenase-based NADH regeneration system, was applied in producing diols from mixtures of glucose and glycerol. Entner-Doudoroff pathway had a high regeneration rate of NAD(P)H. This work described a strategy to administrate intracellular NADH/NAD⁺ ratio and improved the concentration of diols. The improvement of NADH/NAD⁺ ratio also effected gene transcription level of the central carbon pathway and cell growth. Finally, the intracellular NADH/NAD⁺ ratio in KP-APZDUT was increased by 92.8% compared to the KP-T and the concentration, yield and productivity of diols were increased to 110.8 g L^-1 , 0.78 mol mol^-1 , and 3.46 g Lh^-1 , respectively. The strategy described here provides an approach to achieve a recombinant strain which is capable of producing diols with high yield and productivity. To the best of our knowledge, the Entner-Doudoroff pathway has not yet been used to produce 1,3-PDO or 2,3-BDO in Klebsiella pneumoniae.