Cyanobacteria are photosynthetic microbes capable of converting solar energy into liquid biofuel like alkanes and ethanol, and biofuel precursors like free fatty acids. They can be thought of as individual machines efficiently transforming sunlight and CO2 into fuel, and like machines they can be engineered with new capabilities. Because they are bacteria they are relatively easy to genetically modify compared to plants and even other photosynthetic microbes like algae. Researchers at the Biodesign Institute of Arizona State University have made several innovations increasing both the quantity and quality of biofuel and biofuel precursors, as well as engineering several features into the organism to help reduce the cost of product recovery.
One of these features involves engineering cyanobacteria to secrete fatty acids, which can be converted into liquid biofuel that can power cars, ships, and planes. The secretion occurs during high-density slow growth and stationary growth phases of the culture, the goal being to maintain a slow growing culture over extended time frames that continuously secretes fatty acids. Continuous secretion removes the costs associated with the "grow-harvest" cycle traditionally associated with algae biofuel production, since turnover and harvesting costs are minimized. The culture can be recycled at the end of its life by using another engineered feature1 which digests the cyanobacterial cell wall to free both membrane bound lipids as well as any remaining internal products into the surrounding culture media where they can be collected. Researchers have also engineered strains to produce alkanes, ethanol, fatty acid methyl esters (FAME), fatty acid ethyl esters (FAEE) and neutral lipids.
Benefits and Advantages
- Photosynthetic organisms typically out produce any plant based biofuel system
- Production is regulated and controllable at the genetic level
- Algae and cyanobacteria growth is renewable and efficient