Biosynthesis of ethylene glycol in Escherichia coli

Abstract

Ethylene glycol (EG) is an important platform chemical with steadily expanding global demand. Its commercial production is currently limited to fossil resources; no biosynthesis route has been delineated. Herein, a biosynthesis route for EG production from D-xylose is reported. This route consists of four steps: D-xylose → D-xylonate → 2-dehydro-3-deoxy-D-pentonate → glycoaldehyde → EG. Respective enzymes, D-xylose dehydrogenase, D-xylonate dehydratase, 2-dehydro-3-deoxy-D-pentonate aldolase, and glycoaldehyde reductase, were assembled. The route was implemented in a metabolically engineered Escherichia coli, in which the D-xylose → D-xylulose reaction was prevented by disrupting the D-xylose isomerase gene. The most efficient construct produced 11.7 g L(-1) of EG from 40.0 g L(-1) of D-xylose. Glycolate is a carbon-competing by-product during EG production in E. coli; blockage of glycoaldehyde → glycolate reaction was also performed by disrupting the gene encoding aldehyde dehydrogenase, but from this approach, EG productivity was not improved but rather led to D-xylonate accumulation. To channel more carbon flux towards EG than the glycolate pathway, further systematic metabolic engineering and fermentation optimization studies are still required to improve EG productivity.

Morphological impact of zinc oxide particles on the antibacterial activity and human epithelia toxicity

“…EG should not exhibit toxicity to E. coli in low concentrations. It has been shown previously that EG can even be biosynthesized in E. coli [50]; therefore, possible traces of it remaining within the porous particle structure are not likely to solely contribute to overall antibacterial effect The increased toxicity could, therefore, be related to possible additional products of reaction and/or synergistic interplay among the main and trace components. This inconsistency in antibacterial activity could also be explained by unforeseen aggregation of the nanoparticles during bioassay.…”

Autonomous production of 1,4-butanediol via a de novo biosynthesis pathway in engineered Escherichia coli

“…Previous studies have shown that deletion of these three genes disables the strain's capability to grow on D-xylose or D-xylonic acid but does not interfere with cellular growth on LB or glucose (Liu et al, 2012;Liu et al, 2013). These results indicated that the strain's central metabolism was not influenced by the ϭϭ blockage of D-xylose metabolism, suggesting that the BD pathway can be introduced to the chassis.…”

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

“…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).…”