(47f) Metabolic Engineering of Cyanobacteria for Bioenergy Production

This research addresses one of the pressing national priorities in the United States: seeking bioenergy for the reduction of America's oil addiction. By using fossil fuels as energy sources, we are facing several problems, such as reduced fossil fuel resources; America's dependence on foreign oils; environmental pollutions and the global warming effect, etc. Development of renewable energy is rapidly embraced by our society and industry to meet the energy growth and emission reduction goals. Bioethanol has recently surged to the forefront of renewable fuels technology. It is thus a valuable alternative of fossil fuels. Most of the current ethanol production is from the fermentation of starch crops. This method suffers from some significant obstacles in the establishment of ethanol as a major player in the fuels market. Energy production from agricultural crops has been found to not to be cost-effective and energy-efficient. It also raises environmental concerns due to its emission of hazardous air pollutants and volatile organic compounds, and CO2 to the environment. The competition of energy vs. food will cause further shortage of the world grain supply and damage to the food security.

We have developed an integrative biological and engineering approach to construct novel cyanobacterium Synechocystis strains for direct conversion of sunlight and CO2 into ethanol. We have successfully transformed the pyruvate decarboxylase (pdc) and alcohol dehydrogenase II (adh) genes from Zymomonas mobilis into Synechocystis sp. PCC 6803. Our preliminary studies have confirmed that it is feasible to create such ethanol producers from cyanobacterial systems. We are continuing our effort to optimize our ethanol production approach so that it may topple the global dependence on fossil fuels. It is found that the photosynthetic cyanobacteria can be redesigned for highly efficient ethanol production by the combination of gene transformation, strain/process development and metabolic modeling/ profiling analysis. Our goal is to create a sound and sustainable method to reduce the cost of ethanol production to the point that the ethanol production is competitive to utilization of fossil fuels.