(12f) Development of Efficient Organisms Using a Combination of Rational Strain Design and Metabolic Evolution

In this study, we demonstrate the use of a combined strategy involving inverse metabolic engineering and metabolic evolution for rational strain development. While metabolic pathway analysis suggests defined genetic modifications, mutations introduced through evolution can be rationalized if the mutations are identified in the genome. We have applied this approach for designing and constructing the most efficient E. coli strains for the production of primary metabolites such as ethanol as well as for the production of complex secondary metabolites like carotenoids. Inverse metabolic engineering based on Elementary Mode Analysis was applied to predict a set of multiple-gene deletions forcing cells to function according to efficient pathways. The constructed strains have been exposed to metabolic evolution in a growth-based selection scheme in selected growth environments. We have recently constructed the designed strains and characterized their performance. Experimental results demonstrate that the designed strains achieve a significantly improved performance in comparison to the wild type under identical conditions. The results, therefore, confirm the validity of the applied strategy for rational strain development.