Construction of an engineered biocatalyst system for the production of medium‐chain α,ω‐dicarboxylic acids from medium‐chain ω‐hydroxycarboxylic acids

Mid-Long Chain Dicarboxylic Acid Production via Systems Metabolic Engineering: Progress and Prospects

Mid-to-long-chain dicarboxylic acids (DCAi, i ≥ 6) are organic compounds in which two carboxylic acid functional groups are present at the terminal position of the carbon chain. These acids find important applications as structural components and intermediates across various industrial sectors, including organic compound synthesis, food production, pharmaceutical development, and agricultural manufacturing. However, conventional petroleum-based DCA production methods cause environmental pollution, making sustainable development challenging. Hence, the demand for eco-friendly processes and renewable raw materials for DCA production is rising. Owing to advances in systems metabolic engineering, new tools from systems biology, synthetic biology, and evolutionary engineering can now be used for the sustainable production of energy-dense biofuels. Here, we explore systems metabolic engineering strategies for DCA synthesis in various chassis via the conversion of different raw materials into mid-to-long-chain DCAs. Subsequently, we discuss the future challenges in this field and propose synthetic biology approaches for the efficient production and successful commercialization of these acids.

Reprogramming Escherichia coli Metabolism for Bioplastics Synthesis from Waste Cooking Oil

The recycle and reutilization of food wastes is a promising alternative for supporting and facilitating circular economy. However, engineering industrially relevant model organisms to use food wastes as their sole carbon source has remained an outstanding challenge so far. Here, we reprogrammed Escherichia coli metabolism using modular pathway engineering followed by laboratory adaptive evolution to establish a strain that can efficiently utilize waste cooking oil (WCO) as the sole carbon source to produce monomers of bioplastics, namely, medium-chain α,ω-dicarboxylic acids (MCDCAs). First, the biosynthetic pathway of MCDCAs was designed and rewired by modifying the β-oxidation pathway and introducing an ω-oxidation pathway. Then, metabolic engineering and laboratory adaptive evolution were applied for improving the pathway efficiency of fatty acids utilization. Finally, the engineered strain E. coli AA0306 was able to produce 15.26 g/L MCDCAs with WCO as the sole carbon source. This study provides an economically attractive strategy for biomanufacturing bioplastics from food wastes, which has a great potentiality to be developed as a wide range of enabling biotechnologies for achieving green revolution.

Engineering of an oleate hydratase for efficient C10-Functionalization of oleic acid

Oleate hydratase catalyzes the hydration of unsaturated fatty acids, giving access to C₁₀-functionalization of oleic acid. The resultant 10-hydroxystearic acid is a key material for the synthesis of many biomass-derived value-added products. Herein, we report the engineering of an oleate hydratase from Paracoccus aminophilus (PaOH) with significantly improved catalytic efficiency (from 33 s^-1 mM^-1 to 119 s^-1 mM^-1), as well as 3.4 times increased half-life at 30 °C. The structural mechanism regarding the impact of mutations on the improved catalytic activity and thermostability was elucidated with the aid of molecular dynamics simulation. The practical feasibility of the engineered PaOH variant F233L/F122L/T15 N was demonstrated through the pilot synthesis of 10-hydroxystearic acid and 10-oxostearic acid via an optimized multi-enzymatic cascade reaction, with space-time yields of 540 g L^-1 day^-1 and 160 g L^-1 day^-1, respectively.