1,3-Propanediol (1,3-PDO) is an important platform chemical which has a wide application in food, cosmetics, pharmaceutical and textile industries. Its biological production using recombinant Escherichia coli with glucose as carbon source has been commercialized by DuPont, but E. coli cannot synthesize coenzyme B₁₂ which is an essential and expensive cofactor of glycerol dehydratase, a core enzyme in 1,3-PDO biosynthesis. This study aims to develop a more economical microbial cell factory using Klebsiella pneumoniae J2B which can naturally synthesize coenzyme B₁₂. To this end, the heterologous pathway for the production of glycerol from dihydroxyacetone-3-phosphate (DHAP), a glycolytic intermediate, was introduced to J2B and, afterwards, the strain was extensively modified for carbon and energy metabolisms including: (i) removal of carbon catabolite repression, (ii) blockage of glycerol export across the cell membrane, (iii) improvement of NADH regeneration/availability, (iv) modification of TCA cycle and electron transport chain, (v) overexpression of 1,3-PDO module enzyme, and (vi) overexpression of glucose transporter. A total of 33 genes were modified and/or overexpressed, and one resulting strain could produce 814 mM (62 g/L) of 1,3-PDO with the yield of 1.27 mol/mol glucose in fed-batch bioreactor culture with a limited supplementation of coenzyme B₁₂ at 4 μM, which is ~10 fold less than that employed by DuPont. This study highlights the importance of balanced use of glucose in the production of carbon backbone of the target chemical (1,3-PDO) and regeneration of reducing power (NADH). This study also suggests that K. pneumoniae J2B is a promising host for the production of 1,3-PDO from glucose.

1,3-丙二醇（1,3-PDO）是一种重要的平台化学品，在食品、化妆品、医药和纺织等行业有着广泛的应用。其使用以葡萄糖为碳源的重组大肠杆菌的生物生产已被杜邦商业化，但大肠杆菌无法合成辅酶 B ₁₂，辅酶 B ₁₂是甘油脱水酶（1,3-PDO 生物合成中的核心酶）的必需且昂贵的辅助因子。本研究旨在使用可自然合成辅酶 B _{12 的}肺炎克雷伯菌J2B开发更经济的微生物细胞工厂. 为此，从糖酵解中间体 3-磷酸二羟丙酮 (DHAP) 生产甘油的异源途径被引入 J2B，随后，该菌株被广泛修饰以进行碳和能量代谢，包括：(i) 去除碳分解代谢物抑制，(ii) 阻断甘油跨细胞膜输出，(iii) NADH 再生/可用性的改善，(iv) TCA 循环和电子传递链的修饰，(v) 1,3-PDO 模块的过表达酶，和 (vi) 葡萄糖转运蛋白的过度表达。总共有 33 个基因被修饰和/或过表达，在补料分批生物反应器培养中，一个产生的菌株可以产生 814 mM (62 g/L) 的 1,3-PDO，产量为 1.27 mol/mol 葡萄糖。补充辅酶 B ₁₂4 μM，比杜邦采用的浓度低约 10 倍。该研究强调了平衡使用葡萄糖在目标化学品 (1,3-PDO) 的碳骨架生产和还原能力 (NADH) 再生中的重要性。该研究还表明，肺炎克雷伯氏菌J2B 是从葡萄糖生产 1,3-PDO 的有希望的宿主。