(2R,3R)-2,3-丁二醇（R,R-BD）可广泛应用于化工、食品、能源、医药等领域。多粘类芽孢杆菌是目前最优的R,R-BD生产菌种，但存在副产物浓度高和产物光学纯度不足的问题。长期以来，多粘类芽孢杆菌基因组层面上的代谢背景不清晰，给菌株的理性改造带来了困难。项目组前期完成了两株高产R,R-BD的多粘类芽孢杆菌基因组测序、功能注释和代谢网络模型构建工作，并对代谢途径部分关键酶进行了鉴定。在此基础上，本项目拟采用系统代谢工程的多途径优化方法改变胞内碳架物质流量分布，提高产物的转化率和光学纯度；同时利用辅酶调控策略对葡萄糖脱氢酶和关键限速酶R,R-BD脱氢酶进行过量表达来优化胞内NADH/NAD+比率；研究系列改造对菌体生长、发酵性能和氧化还原状态的影响，揭示胞内氧化还原状态对代谢网络的调控机制，为R,R-BD高产菌株的理性改造奠定理论基础，同时为类似多元醇生产菌的改造提供有意义的指导。

(2R,3R)-2,3-butanediol (R,R-BD) can be widely used in chemical, food, fuel, and medicine fields. Paenibacillus polymyxa is the optimal R, R-BD-producing strain to date, while the present shortage problems of high concentrations of byproducts and low optical purity of the product hindered its industrialization. Additionally, the metabolic background at genome level of P. polymyxa is not clear, thus it is an obstacle for rationally engineering strains to get potential strain with better fermentation performance. Our team has completed two R, R-BD-producing P. polymyxa strains' genome sequencing, annotation and metabolic network model construction. And some key enzymes in metabolic pathway were also functionally identified at biochemical level. This project intends to adopt systems metabolic engineering approach to change intracellular carbon source flux distribution, and therefore to improve yield and optical purity of the final product. Combination with cofactor engineering strategy, the expression levels of glucose dehydrogenase and rate-limiting enzyme R,R-BD dehydrogenase will also be optimized to reveal the effects of series metabolic engineering on the cell growth, fermentation performance and intracellular redox state. These general conclusions will provide fundamental information for strains improvement to get the higher titer and yield for R,R-BD and analogous polyols production.