Co-expression of phosphoenolpyruvate carboxykinase and nicotinic acid phosphoribosyltransferase for succinate production in engineered Escherichia coli

De novo biosynthesis of nylon 12 monomer ω-aminododecanoic acid

Nylon 12 is valued for its exceptional properties and diverse industrial applications. Traditional chemical synthesis of nylon 12 faces significant technical challenges and environmental concerns, while bioproduction from plant-extracted decanoic acid (DDA) raises issues related to deforestation and biodiversity loss. Here, we show the development of an engineered Escherichia coli cell factory capable of biosynthesizing the nylon 12 monomer, ω-aminododecanoic acid (ω-AmDDA), from glucose. We enable de novo biosynthesis of ω-AmDDA by introducing a thioesterase specific to C12 acyl-ACP and a multi-enzyme cascade converting DDA to ω-AmDDA. Through modular pathway engineering, redesign and dimerization enhancement of the rate-limiting P450, reconstruction of redox and energy homeostasis, and enhancement of oxidative stress tolerance, we achieve a production level of 471.5 mg/L ω-AmDDA from glucose in shake flasks. This work paves the way for sustainable nylon 12 production and offers insights for bioproduction of other fatty acid-derived products.

Central pathway engineering for enhanced succinate biosynthesis from acetate in Escherichia coli

Acetate, a non-food based substrate obtained from multiple biological and chemical ways, is now being paid great attention in bio-manufacturing and have a strong potential to compete with sugar-based carbon source. In this study, acetate can be efficiently converted to succinate by engineered Escherichia coli strains via the combination of several metabolic engineering strategies, including reducing OAA decarboxylation, engineering TCA cycle, enhancement of acetate assimilation pathway and increasing aerobic ATP supply through cofactor engineering. The engineered strain HB03(pTrc99a-gltA, pBAD33-Trc-fdh) accumulated 30.9 mM of succinate in 72 hr and the yield reached the maximum theoretical yield (∼0.50 mol/mol). In the resting-cell experiments, the yield of succinate in HB03(pTrc99a-gltA) and HB03(pTrc99a-gltA, pBAD33-Trc-fdh) dropped dramatically, although the productivity of succinate increased due to the high cell density. Further deletion of icdA, formed HB04(pTrc99a-gltA) and HB04(pTrc99a-gltA, pBAD33-Trc-fdh), increased the yield of succinate in the resting-cell experiments. The highest concentration of succinate achieved 194 mM and the yield reached 0.44 mol/mol in 16 hr by HB04(pTrc99a-gltA, pBAD33-Trc-fdh). The results showed the metabolically engineered E. coli strains have great potential to produce succinate from acetate.

Construction of Escherichia Coli Cell Factories for Production of Organic Acids and Alcohols

Production of bulk chemicals from renewable biomass has been proved to be sustainable and environmentally friendly. Escherichia coli is the most commonly used host strain for constructing cell factories for production of bulk chemicals since it has clear physiological and genetic characteristics, grows fast in minimal salts medium, uses a wide range of substrates, and can be genetically modified easily. With the development of metabolic engineering, systems biology, and synthetic biology, a technology platform has been established to construct E. coli cell factories for bulk chemicals production. In this chapter, we will introduce this technology platform, as well as E. coli cell factories successfully constructed for production of organic acids and alcohols.