1-04: Redesigning E. coli metabolism for anaerobic production of isobutanol

Elementary mode analysis was applied to design an Escherichia coli cell optimized for isobutanol production under anaerobic conditions.  The designed E. coli cell employed the heterologous, obligate anaerobic isobutanol producing pathway, which is an efficient route for the synthesis of reduced metabolites.  E. coli central metabolism was decomposed into 38,219 functional, unique, and elementary pathways, six of which provided optimal routes for isobutanol production.  The re-designed cell was constrained to employ these pathways through deletion of 7 chromosomal genes, addition of 2 heterologous genes, and over-expression of 5 genes.  In addition, the cell was specifically designed to tightly couple both biomass and isobutanol production, providing a unique approach for cellular evolution to improve alcohol production and tolerance.  Here we present the design, construction, and characterization of the isobutanol-producing cell and illustrate the agreement between the model prediction and experimental data.