Engineering a novel biosynthetic pathway in Escherichia coli for production of renewable ethylene glycol

Abstract

Ethylene glycol (EG) is an important commodity chemical with broad industrial applications. It is presently produced from petroleum or natural gas feedstocks in processes requiring consumption of significant quantities of non-renewable resources. Here, we report a novel pathway for biosynthesis of EG from the renewable sugar glucose in metabolically engineered Escherichia coli. Serine-to-EG conversion was first achieved through a pathway comprising serine decarboxylase, ethanolamine oxidase, and glycolaldehyde reductase. Serine provision in E. coli was then enhanced by overexpression of the serine-biosynthesis pathway. The integration of these two parts into the complete EG-biosynthesis pathway in E. coli allowed for production of 4.1 g/L EG at a cumulative yield of 0.14 g-EG/g-glucose, establishing a foundation for a promising biotechnology.

Increased production of L-serine in Escherichia coli through Adaptive Laboratory Evolution

“…L-serine is currently used in cosmetic and pharmaceuticals industries with an estimated annual demand of 400 tons (Leuchtenberger et al, 2005). An efficient serine production strain could also be used as a platform for the production of ethanolamine and renewable ethylene glycol (Pereira et al, 2016). It is therefore highly attractive to produce L-serine at high yields and titers from glucose.…”

Exploring biochemical pathways for mono-ethylene glycol (MEG) synthesis from synthesis gas

“…For instance, only MEG2, MEG5, and MEG7 resulted in MEG-yields similar to the theoretical yields of 0.74 g MEG/g H 2 +CO 2 and 0.44 g MEG/g CO for M. thermoacetica, and only MEG5 and MEG7 produced the theoretical MEG-yields for C. ljungdahlii ( Figures 8A and 8B). Also, the same pathways yielded different MEG on different substrates as evident from the estimated yields of MEG1, MEG3, MEG4, MEG6, and the published MEG-producing pathways (Liu et al, 2013;Pereira et al, 2016b).…”

“…Using these criteria, the pathways were also compared with the published biosynthetic pathways of MEG-production from xylose (Liu et al, 2013) and glucose (Pereira et al, 2016b).…”

“…Furthermore, the industrial process also suffers from low selectivity of MEG because higher order glycols are also produced in the process due to the increased reactivity of Ethylene oxide towards MEG than to water (Forkner et al, 2000;Rebsdat and Mayer, 2000). It is thus of interest to explore the routes for biological production of MEG from renewable feedstocks such as sugars using engineered microbial organisms, and this interest has obtained significant attention from the scientific community recently (Alkim et al, 2015;Liu et al, 2013;Pereira et al, 2016a;Pereira et al, 2016b;Stephanopoulos et al, 2013).…”

“…So far, bio-based production of MEG using engineered Escherichia coli strains has been reported from pentose and hexose sugars, including xylose (Alkim et al, 2015;Liu et al, 2013;Pereira et al, 2016a), arabinose (Pereira et al, 2016a), and glucose (Pereira et al, 2016b). These processes are very promising since the sugars are abundant in lignocellulosic biomass feedstocks obtained from agricultural wastes, forestry residues, grasses, and woody materials (Anwar et al, 2014;Menon and Rao, 2012).…”