Our biofuels research involves a photosynthetic cyanobacterium Synechocystis 6803. Many people first meet this green microbe in their swimming pool when they fall behind on their pool maintenance. For researchers in the Curtiss lab cyanobacteria are not the problem but rather a solution to the world’s energy needs. Through the use of sophisticated genetic techniques we have created a strain of cyanobacteria that secretes fatty acids. These fatty acids can be converted into liquid biofuel that can be used to power vehicles and planes. Our cyanobacteria are miniature factories, taking sunlight and CO2 as an input, and producing fuel as an output. They are a clean, carbon neutral, and sustainable method of producing energy.
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There are two key transformations that turn wild cyanobacteria into miniature fuel factories. First the biochemical pathways that make the cyanobacteria’s normal lipid components are modified to produce higher quantities as well as higher quality lipids. Then the cell walls are weakened by different techniques to allow more of the lipids produced inside to get out. In addition to these key transformations, researchers are removing many of the cyanobacteria functions that are no longer needed for biofuel synthesis. This ‘optimization’ of the organism seeks to use as much of the organism’s energy as possible for lipid production, minimizing or even eliminating other biochemical systems that are not directly engaged in lipid production. Optimization is a two edged sword. As we optimize the organism to produce more lipids we also remove the organism’s ability to survive in a variety of environments. The science and genetics involved in balancing all these goals is one of the things that makes this field intellectually challenging and exciting.
The specific goals of our Biofuels program are:
- Optimizing the expression of genes encoding enzymes needed for free fatty acid (FFA)
- Over expressing these genes by encoding on multi-copy plasmids stabilized by balanced-lethal technologies.
- Eliminating genes encoding enzymes for competing pathways and reduction of genome size by eliminating non-essential genes and operons.
- Engineering strains and culture conditions to inhibit, if not eliminate, growth of contaminating heterotrophs that might consume produced FFAs.
- Developing means to capture FFAs concomitant with production and secretion.
- Developing a process for genetically controlled induction of autoaggregation to concentrate biomass without need for filtration and/or centrifugation.
- Developing a method for liberating membrane lipids at high temperatures and high density in the dark.
- Developing means for biocontainment such that any escaping genetically modified cyanobacteria could not survive in the environment.
For additional information on our Biofuels work please see our papers.