Anaerobic Expression of Pyruvate Dehydrogenase for Producing Biofuels in Fermentative Pathways

Due to political instability in oil-producing nations, growing concern about global warming and a need for indigenous energy resources, the scientific community shoulders the responsibility to identify and develop an economically viable and environmentally friendly fuel alternative. Higher alcohols, such as butanol and isobutanol that can be produced from the same biomass as ethanol are attractive second-generation biofuels both due to their higher energy content as well as their low hygroscopicity. However, the production processes for higher alcohols are not efficient enough to compete economically as a transportation fuel. The overall objective for the Phase I and the phase II projects is the development of an isobutanol production strain with a production yield high enough to enable commercialization in phase III. During the Phase I project, microorganisms were engineered that produced isobutanol at yield, titer, and productivity values that proved feasibility of the technology. The Phase II project will increase the yield of the isobutanol process to levels sufficient for commercialization. Commercial Applications and other Benefits as described by the awardee: Isobutanol has applications both in the transportation market as well as in the chemicals market. One of the biggest drawbacks with ethanol as a fuel is its hygroscopicity and the resulting inability to transport ethanol using the existing infrastructure. Using isobutanol as a replacement for ethanol overcomes this limitation as well as increases the energy content per gallon, bringing it closer to gasoline. In the chemicals market, the demand for isobutanol is growing at an annual rate of 4.5%. The growing price of oil has resulted in a corresponding increase in the cost of isobutanol. This project will promote the establishment of a renewable process for isobutanol production that is economically competitive with the petro-chemical market. This not only delivers a better second generation biofuel but also reduces the dependence on imported oil, lowers green-house gas emissions, and expands the use of bio-based products in the chemicals market.