Biofuel Production Coupled to Bioremediation of Industrial Flue Gas

Can a harmful alga also be beneficial? Heterosigma akashiwo is considered a harmful algal species due to its ability to form massive, ecosystem disruptive blooms and its toxicity  toward fish and shellfish. This project will investigate the potential beneficial use of Heterosigma akashiwo to remove harmful gasses from industrial flue gas while producing commercially valuable products such as biodeisel fuel.

With the threat of increasing atmospheric CO2 levels and the rising costs of fossil fuels, there is a growing interest in using photosynthetic microalgae for biofuel production coupled to bioremediation of CO2 from industrial flue gas emissions.  In addition to high CO2 concentrations, the presence of nitrogen oxides (NOx) in flue gas also causes major environmental and human health problems.  The Northeast and Mid-Atlantic regions of the US are particularly affected by NOx in flue gas emissions. In the Chesapeake Bay, for example, it is estimated that more than a quarter of the nitrogen entering the bay annually comes from atmospheric NOx. The majority (90%) of NOx in flue gas is in the form of nitric oxide (NO), a toxic gas that easily crosses cell membranes, diffuses through the cytoplasm, and reacts within the cell to generate a variety of cytotoxic products.  Unfortunately, the high concentration of NO in flue gas inhibits the growth of microalgae and previous attempts to utilize current biodiesel-producing strains of microalgae for growth on emissions containing NOx have been largely unsuccessful.  Establishing and/or engineering algal strains suitable for biofuel production that can utilize and remove CO2 and NOx from flue gas emissions is an important step to developing this process on a commercially viable scale.

Research in Coyne’s laboratory at UD shows that the unicellular alga, Heterosigma akashiwo, is capable of metabolizing gaseous inputs of CO2 and NO. This capability may be due to the presence of a novel chimeric enzyme, NR2-trHbN, currently under investigation in Coyne’s lab. Preliminary data supports the hypothesis that this enzyme is involved in NO metabolism, converting NO to innocuous nitrate, which is then assimilated into algal biomass. Research by others also identified H. akashiwo as a
candidate for use in biodiesel production and showed that this species is capable of achieving a high total lipid content composed of desirable saturated fatty acids. Together, these factors suggest that H. akashiwo may be an ideal candidate for the simultaneous production of sustainable biofuels and the bioremediation of key pollutants from industrial emissions.
This  project will investigate the utilization of H. akashiwo for the bioremediation of CO2 and NOx and optimize production of high quality lipids in this species when grown on a model flue gas. Due to its classification as a harmful algal species, all experiments will be conducted in controlled laboratory settings. The specific objectives of this project are to:
(1) Evaluate the long-term effects of model flue gas on H. akashiwo physiology and molecular biology,
(2) Evaluate the ability of H. akashiwo to utilize NO as a nitrogen source,
(3) Evaluate the impact of saturating light intensities on lipid production and fatty acid composition in H. akashiwo grown on model flue gas, and
(4) Investigate opportunities for commercial applications for this technology.
  
This project is funded in part by Sea Grant to K. Coyne and J. Stewart,  The project addresses Sea Grant's priority areas “Healthy Coastal Ecosystems” and “Sustainable Coastal Development” by contributing to the development of sustainable technology and renewable energy resources.  This project is also funded by the USDA National Institute of Food and Agriculture (NIFA): Agriculture and Food Research Initiative (AFRI; Competitive Grant #2011-67012-31175)  to J. Stewart. This project is aligned with the AFRI program priority to secure America's energy future through renewable biofuel, and addresses the NIFA AFRI focused research objective of carbon sequestration and sustainable bioenergy production. 

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