Saionz, Virginia, Biology, Bucknell University, 701 Moore Avenue, Lewisburg, Pennsylvania, 17837, firstname.lastname@example.org; Stowe, Emily, Biology, Bucknell University, 701 Moore Avenue C7890, Lewisburg, Pennsylvania, 17837, email@example.com.
Cyanobacteria are a major contributor to primary productivity and oxygen production within freshwater aquatic ecosystems. Cyanobacteria utilize a light harvesting complex called the phycobilisome (PBS) to expand the wavelengths of light available for photosynthesis. The phycobilisome contains phycobiliproteins; allophycocyanin (AP), phycocyanin (PC) and phycoerythrin (PE) that allow for the absorption and transduction of light in different environmental light conditions.
Nitrogen is an essential nutrient used in amino acid synthesis and biomolecule production. Cyanobacteria can uptake nitrogen through environmental nitrates or ammonia or through the process of nitrogen fixation by which atmospheric nitrogen (N2) is converted to ammonia (NH3). The phycobilisome is a sink for nitrogen and other essential nutrients as it can comprise up to 50% of cellular proteins in cyanobacteria. In the absence of nitrogen, the breakdown of the phycobilisome may occur to conserve nutrients and harvest cellular nitrogen.
The sequenced genome of the SR411 strain of Pseudanabaena, isolated from the Susquehanna River, contains nitrogenase synthesis genes (NifHDK) and should therefore have the ability to fix atmospheric nitrogen. The ability of SR411 to survive nitrogen starvation has yet to be studied. In order to investigate the ability of SR411 to fix nitrogen, we compared bacteria starved of and supplemented with nitrogen and measured its growth and phycobiliprotein levels over time. Additionally, we compared the growth and phycobiliprotein levels of WFMT1A and Fremyella diplosiphon UTEX 481, two cyanobacteria known to produce nitrogen fixing heterocyst structures, to determine if nitrogen starvation altered the development and survival of other nitrogen fixing cyanobacteria.
Nitrogen Fixation, Microbial Genetics, Cyanobacteria, Susquehanna