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Hydrogen Production by Cyanobacteria. Dr. Teresa Thiel University of Missouri – St. Louis. Light micrograph of filaments of Anabaena sp. with heterocysts. Functions of heterocysts and vegetative cells. Expression of nitrogen fixation genes only in heterocysts .
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Hydrogen Production by Cyanobacteria Dr. Teresa Thiel University of Missouri – St. Louis
Light micrograph of filaments of Anabaena sp. with heterocysts
Expression of nitrogen fixation genes only in heterocysts Green cells are heterocysts that are able to fix nitrogen and make hydrogen. Red cells are vegetative cells that cannot fix nitrogen and make hydrogen. Arrows indicate heterocysts identified by brightfield microscopy. Bar=10 mM
Schindelin, H.,Kisker, C.,Schlessman, J.L.,Howard, J.B.,Rees, D.C. Nature 387:370-376 , 1997.
Adding the dinitrogenase reductase components the first of four subunits
Half of one nitrogenase molecule with both dinitrogenase and dinitrogenase reductase components
The other half of one nitrogenase molecule with both dinitrogenase and dinitrogenase reductase components
Building half of one nitrogenase molecule - starting with the dinitrogenase reductase components
Building half of one nitrogenase molecule - starting with the dinitrogenase reductase components
Building half of one nitrogenase molecule - adding the dinitrogenase components
Half of Nitrogenase Finishing half of one nitrogenase molecule - adding the second dinitrogenase component
8 [H+ + e-] Reduces nitrogenase reductase Reduced nitrogenase reductase
N N 8 [H+ + e-] Reduces nitrogenase reductase
Anabaena produces hydrogen in a bioreactor Modified from Lindberg, P. Cyanobacterial Hydrogen Metabolism. Dissertation. University of Uppsala.2003.
H2 fueling station http://www.actransit.org/environment/hyroad_richmond.wu
Engineer heterocysts to express an efficient hydrogenase CP1 hydrogenase from Clostridium pasteurianum http://www.chemistry.montana.edu/~john.peters/gallery/structure1.html
Engineer a strain with a very high frequency of heterocysts A high frequency of heterocysts as depicted here (artistic rendering, not actual photo) could allow cultures to produce large amounts of hydrogen using nitrogenase or hydrogenase.
Advantages of Anabaena system • Requires only sunlight, air and water to grow and produce hydrogen • In contrast to other algal systems, it produces hydrogen in cells growing in air • No fossil fuels are required and oxygen is the only byproduct • Has been demonstrated to produce ¼ of the volume of a bioreactor of hydrogen per day (Tsygankov, A. A., et al. Biotechnol. Bioeng. 80, 777, 2002)
N N 8 [H+ + e-] Reduces nitrogenase reductase Dinitrogenase reduces dinitrogen to ammonia and hydrogen