Among the obvious cycling processes are photosynthesis and nitrogen fixation. It is difficult to perform these two functions in the same cell because the two processes are at odds with one another. Fixing nitrogen requires nitrogenase, a catalyst that helps the chemical reaction move forward. Unhelpfully, the oxygen produced by photosynthesis degrades nitrogenase, making nitrogen fixation difficult or impossible in photosynthetic organisms.
Other filamentous cyanobacteria perform photosynthesis and nitrogen fixation in different cells. As a single-celled bacterium, however, Cyanothece cannot separate these antagonistic processes in space. But it can separate them in time. While Cyanothece is active in the daytime for photosynthesis, this research shows that it also has quite the nightlife, unlike other cyanobacteria.
Agreeing with previous studies, this study found that Cyanothece genes for photosynthesis turn on during the day and genes for nitrogen fixation turn on at night. The surprise is the tremendous impact the day-night cycle has on the overall physiology of the cell.
It goes far beyond just the aspects of nitrogen fixation and photosynthesis, said Pakrasi, who also directs Washington Universitys International Center for Advanced Renewable Energy and Sustainability (I-CARES) to encourage and coordinate university-wide and external collaborative research in the areas of renewable energy and sustainability - including biofuels, carbon dioxide mitigation and coal-related issues. The university will invest more than $55 million in the initiative.
Cyanotheces Dark Period
To see the effect of day-night cycles on the overall physiology of Cyanothece, lead author Jana Stckel, Ph.D., Washington University post-doctoral researcher, and other members of this re
|Contact: Gayle Geren|
Washington University in St. Louis