Engineering improved ethylene production: Leveraging systems biology and adaptive laboratory evolution

• Published in: Metabolic engineering 2021-09, Vol.67, p.308-320
• Main Authors: Vaud, Sophie, Pearcy, Nicole, Hanževački, Marko, Van Hagen, Alexander M.W., Abdelrazig, Salah, Safo, Laudina, Ehsaan, Muhammad, Jonczyk, Magdalene, Millat, Thomas, Craig, Sean, Spence, Edward, Fothergill, James, Bommareddy, Rajesh Reddy, Colin, Pierre-Yves, Twycross, Jamie, Dalby, Paul A., Minton, Nigel P., Jäger, Christof M., Kim, Dong-Hyun, Yu, Jianping, Maness, Pin-Ching, Lynch, Sean, Eckert, Carrie A., Conradie, Alex, Bryan, Samantha J.
• Format: Article
• Language: English
• Subjects: Adaptive evolution; BASIC BIOLOGICAL SCIENCES; Directed evolution; E. coli; ethylene; ethylene forming enzyme; Fermentation; laboratory evolution; Metabolic engineering; protein engineering; Systems biology
• ISSN: 1096-7176; 1096-7184
• DOI: 10.1016/j.ymben.2021.07.001

Ethylene is a small hydrocarbon gas widely used in the chemical industry. Annual worldwide production currently exceeds 150 million tons, producing considerable amounts of CO2 contributing to climate change. The need for a sustainable alternative is therefore imperative. Ethylene is natively produced by several different microorganisms, including Pseudomonas syringae pv. phaseolicola via a process catalyzed by the ethylene-forming enzyme (EFE), subsequent heterologous expression of EFE has led to ethylene production in non-native bacterial hosts including Escherichia coli and cyanobacteria. However, solubility of EFE and substrate availability remain rate-limiting steps in biological ethylene production. We employed a combination of genome-scale metabolic modelling, continuous fermentation, and protein evolution to enable the accelerated development of a high efficiency ethylene producing E. coli strain, yielding a 49-fold increase in production, the most significant improvement reported to date. Furthermore, we have clearly demonstrated that this increased yield resulted from metabolic adaptations that were uniquely linked to EFE (wild type versus mutant). Our findings provide a novel solution to deregulate metabolic bottlenecks in key pathways, which can be readily applied to address other engineering challenges. •First example of growth-coupled ethylene production.•Increased ethylene productivity in E. coli 49-fold.•Increased ethylene-forming enzyme (EFE) solubility in vivo.•Distal mutations in EFE influence the active site.