Photosynthetic Bacteria for Better Biofuels and Beyond

ASU scientists are developing a new, renewable source of biodiesel and other green products. Our scientists are developing genetically optimized versions of photosynthetic bacteria, called cyanobacteria, that will use sunlight, water and carbon dioxide to over-produce and secrete fatty acids as a raw material for the production of biofuel. This revolutionary concept shifts the focus from growing dense cultures of algae or bacteria for harvest of fats to a continuous microbial production system as biocatalysts (mini factories) from which a renewable fuel feedstock, namely fatty acids, is collected and converted into biofuel.  This system has distinct advantages over traditional biofuels approaches including:

• Highly efficient conversion of solar energy into biofuel-compatible feedstock with efficiencies that are closer to theoretical maxima. The reason: cyanobacteria are engineered to be mini-factories, churning out fatty acids in a stationary phase of growth.
• Little or no need for processing of plant or bacterial biomass, which is complex and costly.
• No requirement for arable land; cyanobacteria are grown in transparent enclosures called photobioreactors (PBRs) that can be located anywhere there is sunlight.
• Production systems can be located in urban as well as rural areas, reducing transportation costs and associated environmental impact.
• Produced fuels are virtually carbon-neutral. Like a plant, the cyanobacteria use carbon dioxide for photosynthesis, and photosynthesis products are used directly for biofuel production. 
• Biofuel production does not compete with production of food or commodity crops.
• Growth systems are enclosed and therefore require less water than plant-based biofuels.
• Biofuel production does not require net inputs of fertilizer, so soil depletion/contamination concerns are eliminated.
• Cyanobacteria can be easily modified to improve production and conversion efficiencies or even produce other useful substances.

 

 

The project is a continuation of an earlier ASU research effort, called the Tubes in the Desert project, which developed cyanobacteria as a feedstock for biodiesel production, as well as benchtop and large scale photobioreactors to optimize growth and production. This two-year $4.7 million project, made possible by funding from Science Foundation Arizona, British Petroleum and ASU, was completed in 2009.  The new $5.2 million project, led by ASU School of Life Sciences professor Wim Vermaas, is funded by a branch of the US Department of Energy, the Advanced Research Projects Agency-Energy (ARPA-E) and will be completed in two phases over a two-year period.

In Phase 1, researchers will optimize a strain of cyanobacteria that can efficiently produce and secrete fatty acids into the culture media at all stages of growth while concurrently advancing the design of the bench top and roof top PBR systems previously developed here at ASU.

Phase 2 will focus on integration of the various components of genetic and PBR engineering by continuing to optimize the microorganism for our process and placing more attention on
scale-up efforts.  This will include testing the mutant strains in a large-scale roof top bioreactor and testing the production in systems at pilot scale and in a representative environment. 

Throughout this two-year project effective fatty acid production will be partnered with technologies that efficiently transform these fatty acids into liquid transportation fuels and that are modeled for commercial scale application.