Metabolic Engineering of Escherichia coli for High-Yield Production of (R)-1,3-Butanediol

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 3hydroxybutyrate as an intermediate.

Automated summary

Efforts to improve the production efficiency of (R)-1,3-BDO by Escherichia coli through different metabolic engineering strategies have successfully optimized key pathway enzymes, increased NADPH supply, optimized fermentation conditions, and reduced byproducts formation. The best engineered strain can efficiently produce (R)-1,3-BDO with a yield of 0.6 mol/mol glucose, corresponding to 60% of the theoretical yield. Additionally, the feasibility of aerobically producing 1,3-BDO via a new pathway using 3-hydroxybutyrate as an intermediate has been demonstrated.