University of Kentucky CBET-0828817
Wayne R Curtis Pennsylvania State University, University Park CBET 0828648
Intellectual merit
The primary objective of this project is to genetically engineer algae for the production of renewable and ecologically sustainable petroleum grade oils that are suitable for processing into combustible fuels (octanes suitable for internal combustible engines) and other petroleum-based products. This project leverages the Principal Investigators (PIs) recent success in isolating the genes coding for the biosynthesis of rather unique branched-chain, unsaturated hydrocarbons (methylated triterpenes), and the development of novel tools to engineer metabolic shunts for high-level terpene production in terrestrial plants. The PIs' specific aims are to fully characterize these unique triterpene biosynthetic enzymes, to assess the capacity of transgenic algae engineered with the respective genes for their ability to accumulate high-levels of the corresponding petroleum-based oils, and finally to evaluate bioreactor design and operational strategies for growing high density algal cultures and improving the capture efficiency for solar radiation. The proposed collaborative research brings together genetic engineering proof-of-principle with novel process engineering advances in algae culture required to evaluate these alterative platforms of agri-culture and alga-culture for commodity-scale displacement of fossil fuels with renewable, green-house-gas neutral biofuels.
Broader impacts
The proposed work represents a strong interdisciplinary effort between chemists, biochemists and engineers, involving undergraduate and graduate students and postdoctoral associates, in an effort to shed new insights into how metabolic pathways might be engineered for enhanced value using emerging technologies.
SUMMARY ACCOMPLISHMENTS: The research team from Pennsylvania State University (Dr. Wayne Curtis) and the University of Kentucky (Dr. Joe Chappell) achieved two critical goals for advancing economical production of biofuels from algae. The Chappell lab has discovered and characterized the genes that make a biofuel which is essentially the same as crude oil and superior in many ways to alternative alcohol or fat-derived (biodiesel) biofuels. The Curtis lab developed photobioreactor systems and control strategies that allow the researchers to grow algae continuously to cell concentrations that are many-fold higher than previously achieved. RESULTS & SIGNIFICANCE: While there are many options for biofuel molecules, nearly all have limitations such as the need to use energy to distill alcohol, or the removal of water after making biodiesel from fatty acids. In contrast, the molecule that is being produced in the research done at Penn State and the University of Kentucky has focused on has long been identified as ideal both for separation since it is a hydrocarbon that floats on water, and for conversion into gasoline. This molecule is known to have contributed to current oil reserves when the algae that makes it (Botryococcus braunii) was apparently a dominant algae form on the planet. However, until now, B. braunii is the only organism that is known to make this molecule. Now that the genes have been isolated for its synthesis, there is the potential to express this gene in many different organisms to produce this biofuel. Algae has the potential for very high yields per acre that harnesses sunlight and CO2 instead of sugar or carbohydrate that is fed to other biofuel microorganisms. A fundamental problem in producing biofuels from algae is trying to grow algae to high densities, because as the number of algae increases, the light cannot penetrate the culture. As a result, typical pond culture is less than 1 gram of cells per liter (99.9% water), and even more sophisticated photobioreactors are hard pressed to reach 5 gram of cells per liter. In this work, we used a vertical thin trickle film photobioreactor that resulted in algae that can grow to densities of more than 20 gram of cells per liter which were operated with continuous cell harvest for months at a time. The increased cell density will lead to less water handling and lower production costs. BROADER IMPACTS: This research will have a profound impact on the field of biofuels production by introducing what may well be the 'ultimate biofuel molecule' for liquid fuels. Over 30 students were involved in the execution of this work including (3) women graduate students, interns from NewZealand and India, and summer participants from Rose Hulman, Kansas State, and Miami University of Ohio. More details can be found at: www.curtislab.org/research-projects/algae www.nsf.gov/eng/cbet/achieve/1491/2012/chappell.htm www.uky.edu/Ag/Agronomy/Chappell/Research_Areas.html
