Natural Bacterial Communities Associated with Emiliania huxleyi

Coccolithophores are photosynthetic marine microorganisms that cover their eukaryotic cells with calcium carbonate disks. They are of great importance in earth's biogeochemical cycles of oxygen, carbon and sulfur and are essential in marine primary production. The species Emiliania huxleyi is the most abundant coccolithophore micro-alga in modern-day oceans. It creates vast annual blooms that stretch for thousands of square kilometers and can be viewed by satellites from space. These dense blooms end after several weeks with the collapse of the algal population. The collapse of the bloom is usually attributed to viral infections or environmental changes. Recent studies demonstrated that bacteria play an important role in the life and death of E. huxleyi populations. In controlled laboratory experiments, it was shown that the bacterium Phaeobacter inhibens has a dynamic mutualistic-pathogenic interaction with the alga. In a co-culture model system, the microbes first exchange beneficial metabolites, however once the alga ages, the bacterium kills its algal partner. This interaction might contribute to the known E. huxleyi bloom dynamics. Nevertheless, in order to interpret data acquired in the lab, a combination between laboratory findings and field studies will be most beneficial in bridging the complex natural environment of E. huxleyi with the laboratory model system. In this current research I intend to link between lab observations and the marine environment. In order to do so, the identity and relative abundance of bacteria that naturally associate with a stable E. huxleyi population in the gulf of Aqaba will be assessed seasonally in order to account for possible seasonal changes in bacterial composition. In understating who are the bacterial key players in the natural environment of E. huxleyi I hope to attain a wide and unbiased comprehensive view of natural algal-bacterial interactions.