The intellectual merit of this Phase I SBIR research is the development of a biocatalyst for the commercial production of isobutanol using molecular techniques. During Phase I of this proposal, a bacterial microorganism was engineered that produced isobutanol at reasonably high rates and reaching high concentration, indicating that a biotechnological process for the production of isobutanol is feasible. During Phase II research, any limitation to biocatalyst productivity will be removed using molecular techniques resulting in a microorganism that produces isobutanol at a rate that allows for economically competitive production of isobutanol. <br/><br/>The broader impacts of this Phase II SBIR research will be reneweable isobutanol produced for both the transportation fuel market as well as the chemical market. Higher alcohols, such as butanol and isobutanol that can be produced from the same biomass as ethanol are attractive second-generation biofuels due to their higher energy content and their low hygroscopicity. Successful completion of the Phase II work will help enable a process for the biotechnological production of isobutanol that is economically competitive with the petrochemical market. This not only delivers a better second-generation biofuel but also reduces the dependence on imported oil, lowers greenhouse gas emissions and expands the use of biobased products in the chemicals market.