Growth-coupled anaerobic production of isobutanol from glucose in minimal medium with Escherichia coli

Biotechnology for Biofuels and Bioproducts

Research

Steffen Klamt¹  Simon Boecker²  Peter Schulze³ 

[1] Analysis and Redesign of Biological Networks, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106, Magdeburg, Germany;Analysis and Redesign of Biological Networks, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106, Magdeburg, Germany;University of Applied Sciences Berlin, Seestr. 64, 13347, Berlin, Germany;Physical and Chemical Foundations of Process Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106, Magdeburg, Germany;

关键词: Isobutanol;    Redox balance;    Escherichia coli;    Fermentation;    Acetate;    Metabolic engineering;    NADH;   

DOI  :  10.1186/s13068-023-02395-z

 received in 2023-03-06, accepted in 2023-09-18,  发布年份 2023

来源: Springer

【 摘 要 】

BackgroundThe microbial production of isobutanol holds promise to become a sustainable alternative to fossil-based synthesis routes for this important chemical. Escherichia coli has been considered as one production host, however, due to redox imbalance, growth-coupled anaerobic production of isobutanol from glucose in E. coli is only possible if complex media additives or small amounts of oxygen are provided. These strategies have a negative impact on product yield, productivity, reproducibility, and production costs.ResultsIn this study, we propose a strategy based on acetate as co-substrate for resolving the redox imbalance. We constructed the E. coli background strain SB001 (ΔldhA ΔfrdA ΔpflB) with blocked pathways from glucose to alternative fermentation products but with an enabled pathway for acetate uptake and subsequent conversion to ethanol via acetyl-CoA. This strain, if equipped with the isobutanol production plasmid pIBA4, showed robust exponential growth (µ = 0.05 h−1) under anaerobic conditions in minimal glucose medium supplemented with small amounts of acetate. In small-scale batch cultivations, the strain reached a glucose uptake rate of 4.8 mmol gDW−1 h−1, a titer of 74 mM and 89% of the theoretical maximal isobutanol/glucose yield, while secreting only small amounts of ethanol synthesized from acetate. Furthermore, we show that the strain keeps a high metabolic activity also in a pulsed fed-batch bioreactor cultivation, even if cell growth is impaired by the accumulation of isobutanol in the medium.ConclusionsThis study showcases the beneficial utilization of acetate as a co-substrate and redox sink to facilitate growth-coupled production of isobutanol under anaerobic conditions. This approach holds potential for other applications with different production hosts and/or substrate–product combinations.

【 授权许可】

CC BY   
© BioMed Central Ltd., part of Springer Nature 2023

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