Fermentative production of enantiomerically pure S-1,2-propanediol from glucose by engineered E. coli strain

Metabolic Engineering and Regulation of Diol Biosynthesis from Renewable Biomass in Escherichia coli

As bulk chemicals, diols have wide applications in many fields, such as clothing, biofuels, food, surfactant and cosmetics. The traditional chemical synthesis of diols consumes numerous non-renewable energy resources and leads to environmental pollution. Green biosynthesis has emerged as an alternative method to produce diols. Escherichia coli as an ideal microbial factory has been engineered to biosynthesize diols from carbon sources. Here, we comprehensively summarized the biosynthetic pathways of diols from renewable biomass in E. coli and discussed the metabolic-engineering strategies that could enhance the production of diols, including the optimization of biosynthetic pathways, improvement of cofactor supplementation, and reprogramming of the metabolic network. We then investigated the dynamic regulation by multiple control modules to balance the growth and production, so as to direct carbon sources for diol production. Finally, we proposed the challenges in the diol-biosynthesis process and suggested some potential methods to improve the diol-producing ability of the host.

In Silico Design Strategies for the Production of Target Chemical Compounds Using Iterative Single-Level Linear Programming Problems

The optimization of metabolic reaction modifications for the production of target compounds is a complex computational problem whose execution time increases exponentially with the number of metabolic reactions. Therefore, practical technologies are needed to identify reaction deletion combinations to minimize computing times and promote the production of target compounds by modifying intracellular metabolism. In this paper, a practical metabolic design technology named AERITH is proposed for high-throughput target compound production. This method can optimize the production of compounds of interest while maximizing cell growth. With this approach, an appropriate combination of metabolic reaction deletions can be identified by solving a simple linear programming problem. Using a standard CPU, the computation time could be as low as 1 min per compound, and the system can even handle large metabolic models. AERITH was implemented in MATLAB and is freely available for non-profit use.

A comprehensive review on microbial production of 1,2-propanediol: micro-organisms, metabolic pathways, and metabolic engineering

1,2-Propanediol is an important building block as a component used in the manufacture of unsaturated polyester resin, antifreeze, biofuel, nonionic detergent, etc. Commercial production of 1,2-propanediol through microbial biosynthesis is limited by low efficiency, and chemical production of 1,2-propanediol requires petrochemically derived routes involving wasteful power consumption and high pollution emissions. With the development of various strategies based on metabolic engineering, a series of obstacles are expected to be overcome. This review provides an extensive overview of the progress in the microbial production of 1,2-propanediol, particularly the different micro-organisms used for 1,2-propanediol biosynthesis and microbial production pathways. In addition, outstanding challenges associated with microbial biosynthesis and feasible metabolic engineering strategies, as well as perspectives on the future microbial production of 1,2-propanediol, are discussed.

Metabolic engineering of 1,2-propanediol production from cellobiose using beta-glucosidase-expressing E. coli

Microbial 1,2-propanediol production using renewable feedstock is a promising method for the sustainable production of value-added fuels and chemicals. We demonstrated the metabolically engineered Escherichia coli for improvement of 1,2-propanediol production using glucose and cellobiose. The deletion of competing pathways improved 1,2-propanediol production. To reduce carbon flux toward downstream glycolysis, the phosphotransferase system (PTS) was inactivated by ptsG gene deletion. The resultant strain, GL3/PD, produced 1.48 ± 0.01 g/L of 1,2-propanediol from 20 g/L of glucose. A sugar supply was engineered by coexpression of β-glucosidase (BGL). The strain expressing BGL produced 1,2-propanediol from cellobiose at a concentration of 0.90 ± 0.11 g/L with a yield of 0.15 ± 0.01 g/g glucose (cellobiose 1 g is equal to glucose 1.1 g). As cellobiose or cellooligosaccharides a carbon source, the feasibility of producing 1,2-propanediol using an E. coli strain engineered for β-glucosidase expression are demonstrated.

Production of C2-C4 diols from renewable bioresources: new metabolic pathways and metabolic engineering strategies

C2-C4 diols classically derived from fossil resource are very important bulk chemicals which have been used in a wide range of areas, including solvents, fuels, polymers, cosmetics, and pharmaceuticals. Production of C2-C4 diols from renewable resources has received significant interest in consideration of the reducing fossil resource and the increasing environmental issues. While bioproduction of certain diols like 1,3-propanediol has been commercialized in recent years, biosynthesis of many other important C2-C4 diol isomers is highly challenging due to the lack of natural synthesis pathways. Recent advances in synthetic biology have enabled the de novo design of completely new pathways to non-natural molecules from renewable feedstocks. In this study, we review recent advances in bioproduction of C2-C4 diols, focusing on new metabolic pathways and metabolic engineering strategies being developed. We also discuss the challenges and future trends toward the development of economically competitive processes for bio-based diol production.