Carbon Usage and Gene Sequencing of Ruegeria pomeroyi

Undergraduate: Martina Savage

Faculty Advisor: Scott Gifford
Department: Biology

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The ocean is an ever changing chemical environment with multiple functions, one of which being the storage of dissolved carbon. Much of this carbon is taken up by a diverse set of marine microbial life, so determining how it's cycled through bacteria is key in determining what happens to atmospheric carbon when it enters the ocean, and how changes in bacterial populations will affect ocean chemistry. My research focuses on determining which organic molecules are being used by Ruegeria pomeroyi (strain DSS-3), a member of the Roseobacter clade that can make up 10-20% of all oceanic bacteria. My goal was to identify which R. pomeoyi genes are involved in organic matter cycling. To do this I analyzed the genome of DSS-3 for genes annotated as carbon transporters. I found that DSS-3 contains an ABC transporter that has all the protein subunits necessary for making a complete transporter of glycerol. Based on this bioinformatic evidence, I hypothesized that DSS-3 is able to utilize glycerol as a carbon source. I devised one experiment involving DSS-3 growth in various concentrations of glycerol in both rich media (¿¿ YTSS) and minimal media (marine basal media), and one involving growing R. pomeoyi plates with and without glycerol to compare growth. In both instances, it was proven that DSS-3 grows the best in the presence of glycerol as their source of carbon. The results further define the carbon niche of an important ocean bacterium and their impact on ocean biogeochemistry.