Applied Microbiology and Biotechnology

, Volume 95, Issue 4, pp 1083–1094

Elucidating and reprogramming Escherichia coli metabolisms for obligate anaerobic n-butanol and isobutanol production

Bioenergy and biofuels

DOI: 10.1007/s00253-012-4197-7

Cite this article as:
Trinh, C.T. Appl Microbiol Biotechnol (2012) 95: 1083. doi:10.1007/s00253-012-4197-7


Elementary mode (EM) analysis based on the constraint-based metabolic network modeling was applied to elucidate and compare complex fermentative metabolisms of Escherichia coli for obligate anaerobic production of n-butanol and isobutanol. The result shows that the n-butanol fermentative metabolism was NADH-deficient, while the isobutanol fermentative metabolism was NADH redundant. E. coli could grow and produce n-butanol anaerobically as the sole fermentative product but not achieve the maximum theoretical n-butanol yield. In contrast, for the isobutanol fermentative metabolism, E. coli was required to couple with either ethanol- or succinate-producing pathway to recycle NADH. To overcome these “defective” metabolisms, EM analysis was implemented to reprogram the native fermentative metabolism of E. coli for optimized anaerobic production of n-butanol and isobutanol through multiple gene deletion (∼8–9 genes), addition (∼6–7 genes), up- and downexpression (∼6–7 genes), and cofactor engineering (e.g., NADH, NADPH). The designed strains were forced to couple both growth and anaerobic production of n-butanol and isobutanol, which is a useful characteristic to enhance biofuel production and tolerance through metabolic pathway evolution. Even though the n-butanol and isobutanol fermentative metabolisms were quite different, the designed strains could be engineered to have identical metabolic flux distribution in “core” metabolic pathways mainly supporting cell growth and maintenance. Finally, the model prediction in elucidating and reprogramming the native fermentative metabolism of E. coli for obligate anaerobic production of n-butanol and isobutanol was validated with published experimental data.


Elementary mode analysis Metabolic pathway analysis Metabolic pathway design Metabolic pathway alignment Fermentation Advanced biofuels Isobutanol n-Butanol Ethanol Rational strain design Cofactor engineering 

Supplementary material

253_2012_4197_MOESM1_ESM.pdf (409 kb)
ESM 1(PDF 408 kb)

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.Department of Chemical and Biomolecular EngineeringUniversity of TennesseeKnoxvilleUSA

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