The growth and stress response characterization of Synechococcus WH8109 cyanobacteria

Abstract

Oceanic cyanobacteria are amongst the most populous species on the planet and have been found in every ocean around the world. These photosynthetic organisms play a major role in the global carbon cycle. They have adapted to a number of different temperature, light, and nutrient niches. However, as important primary producers in the oceans, these organisms play a vital role which may be threatened by global climate change and pollution. As research on cyanobacterial species progresses, these organisms have been found to show promise as potential sources of biofuel, renewable energy, and agents for bioremediation. In order to utilize these organisms for future engineering applications and basic scientific research, it is important to be able to grow the organism in a stable and reproducible manner. This research characterizes the growth of Synechococcus WH8109 in the laboratory. In the laboratory, cell culture densities of greater than 109 cells/mL with a doubling time of approximately 24 hours were achieved when grown at 28'C with a 24 hour light cycle in sea water and artificial salt water media. Not only did cyanobacteria evolve long before their distant enteric cousins, but they harness nearly all of their energy through photosynthesis. The photosystem is constantly subjected to photo-oxidative damage and degradation. Interesting insight may be gained by studying this complex repair process in the bacterial counterpart to plants, prior to applying these concepts to higher order plant species. Chaperones have been implicated in this repair process. In order to better characterize the stress response of WH8109, I have also isolated the Synechococcus homologue of GroEL using anion exchange and gel filtration chromatography and sucrose gradient centrifugation. The expression levels of this chaperone were analyzed under normal and stress conditions and they have been shown to respond to heat shock and infection.