To turn microorganisms into highly efficient cell factories computational tools, which allow analyzing the network structure of cellular metabolism in order to predict promising engineering targets, are needed. To this end minimal intervention strategies based on constrained minimal cut sets (cMCS) have been developed recently. Here we utilize cMCS to design the most efficient ethanol producing E. coli-strain. For our metabolic model of E. coli we find that at least five deletions are necessary. This is a significant decrease compared to previous designs, which predicted at least seven interventions.