Vermaas, a member of ASUs Center for Bioenergy and Photosynthesis, said that in the laboratory researchers have used a cyanobacterial system to generate a small amount of hydrogen using only solar energy. To optimize the system, the microorganism must be retooled to put most of the energy it gathers from sunlight into compounds useful for biohydrogen production.
The ASU researchers, who have years of experience working in this field, are using a cyanobacterium with a known genome and have developed it into a model organism for genetic and metabolic engineering studies. Using its natural photosynthesis machinery, we are now starting to direct more of the photosynthetic activity into biofuel production, yielding organisms that convert substantially more of the harvested energy into biofuels, Vermaas said.
One of the main challenges for the researchers is finding an enzyme for hydrogen production, called hydrogenase, which can operate in the presence of oxygen. Hydrogenase enzymes are a key component to hydrogen production through the photosynthesis process. However, they currently are very sensitive to oxygen, a natural by-product of the splitting of water (H2O).
If you make photosynthetic hydrogen, you also make oxygen and you have a problem because oxygen inactivates the very enzyme that you want to have working, Vermaas explained.
One part of the project, headed up by Ferran Garcia-Pichel in the School of Life Sciences, is to find heartier forms of hydrogenase. Garcia-Pichel will be looking at systems that occur in nature.
Preliminary data suggest that in a variety of natural habitats cyanobacteria can produce hydrogen, which means that unless there is some way the cells exclude oxygen from the process, their hydrogenase enzyme must be oxygen tolerant, Vermaas said.
Boosting the oxygen tolerance o
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Arizona State University