1,3-Butanediol (1,3-BDO) is an important C4 platform chemical widely used as a solvent in cosmetics and a key intermediate for the synthesis of fragrances, pheromones, and pharmaceuticals. The development of sustainable bioprocesses to produce enantiopure 1,3-BDO from renewable bioresources by fermentation is a promising alternative to conventional chemical routes and has aroused great interest in recent years. Although two metabolic pathways have been previously established for the biosynthesis of (R)-1,3-PDO, the reported titer and yield are too low for cost-competitive production. In this study, we report the combination of different metabolic engineering strategies to improve the production of (R)-1,3-BDO by Escherichia coli, including (1) screening of key pathway enzymes; (2) increasing NADPH supply by cofactor engineering; (3) optimization of fermentation conditions to divert more flux into 1,3-BDO pathway; (4) reduction of byproducts formation by pathway engineering. With these efforts, the best engineered E. coli strain can efficiently produce (R)-1,3-BDO with a yield of 0.6 mol/mol glucose, corresponding to 60% of the theoretical yield. Besides, we also showed the feasibility of aerobically producing 1,3-BDO via a new pathway using 3-hydroxybutyrate as an intermediate.

中文翻译：

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大肠埃希菌代谢工程高产(R)-1,3-丁二醇

1,3-丁二醇 (1,3-BDO) 是一种重要的 C4 平台化学品，广泛用作化妆品中的溶剂，也是合成香料、信息素和药物的关键中间体。开发可持续的生物工艺以通过发酵从可再生生物资源中生产对映体纯 1,3-BDO 是传统化学路线的有前途的替代方案，近年来引起了人们的极大兴趣。尽管之前已经建立了两种代谢途径用于 ( R )-1,3-PDO 的生物合成，但所报道的滴度和产量对于具有成本竞争力的生产来说太低了。在这项研究中，我们报告了不同代谢工程策略的组合，以提高大肠杆菌生产 ( R )-1,3-BDO，包括（1）关键途径酶的筛选；(2) 通过辅因子工程增加 NADPH 供应；(3) 优化发酵条件，将更多通量转移到 1,3-BDO 途径；(4) 通过途径工程减少副产物的形成。通过这些努力，最好的工程大肠杆菌菌株可以有效地生产 ( R )-1,3-BDO，产率为 0.6 mol/mol 葡萄糖，相当于理论产率的 60%。此外，我们还展示了通过以 3-羟基丁酸为中间体的新途径有氧生产 1,3-BDO 的可行性。