Abstract
Bio-based, environmentally benign production of commodity chemicals such as 1,4-butanediol (BDO) from renewable feedstocks is highly challenging due to the lack of natural synthesis pathways. Herein, we present a systematic model-driven evaluation of the production potential for Escherichia coli to produce BDO from renewable carbohydrates (glucose, glycerol). Computational analysis was carried out in order to decipher the metabolic characteristics under various genetic and environmental conditions. Optimal strain designs were achieved using only two (adhE2- alcohol dehydrogenase and cat/sucCD- 4-hydroxybutyrate-CoA transferase/4-hydroxybutyryl-CoA ligase) heterologous reactions; highest yields were attained for: glucose ~0.37 g g-1 (3 knockouts, anaerobically) and glycerol ~0.43 g g-1 (4 knockouts, microaerobically). The maximum achievable production yield was over 95% of the theoretical maximum potential for glucose and over 75% for glycerol. In regards to the genome-scale metabolic model predictions, a metabolically engineered E. coli was created to analyze the new biosynthetic pathway stability and functionality. Considering the preliminary outcomes the strain and pathway is stable under fermentative conditions and a limited quantity of BDO ~1 mg L-1 was obtained, therefore long-term adaptive evolution is mandatory. This study outlines a strain design and analysis pipeline -systems biology-based approach- for non-native compounds production strains.
Highlights
Bio-based, environmentally benign production of commodity chemicals such as 1,4-butanediol (BDO) from renewable feedstocks is highly challenging due to the lack of natural synthesis pathways
Metabolic engineering of microorganisms is a powerful tool, continuously growing and widely used to create new high-performance cellular systems that convert abundant and inexpensive carbohydrates into bio-based fuels, chemicals and polymers [12]. Different renewable feedstocks such as glucose, sucrose, biomass hydrolysate, D-xylose, L-arabinose, and D-galacturonate were used for bio-based BDO production using metabolically engineered host chassis such as E. coli
To obtain BDO from glycerol brings many advantages: glycerol is produced as a by-product of biodiesel fuel production, its low price make glycerol an attractive carbon source, fuels and chemicals can be produced from glycerol at higher rates than from common sugars because the degree of reduction per carbon of glycerol is significantly higher than that of glucose for example [75, 76]
Summary
Bio-based, environmentally benign production of commodity chemicals such as 1,4-butanediol (BDO) from renewable feedstocks is highly challenging due to the lack of natural synthesis pathways. We present a systematic model-driven evaluation of the production potential for Escherichia coli to produce BDO from renewable carbohydrates (glucose, glycerol). One possible way to address these challenges is systems-based design of microorganisms, which aim is harnessing renewable sources and design new highly efficient mini cell factories that convert inexpensive feedstocks, by-products such as glucose, glycerol from different industries into important bio-based chemicals, like 1,4-butanediol (BDO) [13-16]. BDO production still relies primarily on chemical transformation of acetylene, propylene or butane (Reppe chemistry) [1, 13] In this reaction one mole of acetylene reacts with two moles of formaldehyde to produce 1,4-butynediol (Eq 1), after hydrogenation yielding 1,4-butanediol (BDO) (Eq.). Reppe chemistry still accounts for about 40% of the global BDO capacity, key producers using this technology including BASF, Ashland (ISP) and DuPont
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
