Linking microbial metabolism and organic matter cycling through metabolite distributions in the ocean
Johnson, Winifred M.
MetadataShow full item record
Key players in the marine carbon cycle are the ocean-dwelling microbes that fix, remineralize, and transform organic matter. Many of the small organic molecules in the marine carbon pool have not been well characterized and their roles in microbial physiology, ecological interactions, and carbon cycling remain largely unknown. In this dissertation metabolomics techniques were developed and used to profile and quantify a suite of metabolites in the field and in laboratory experiments. Experiments were run to study the way a specific metabolite can influence microbial metabolite output and potentially processing of organic matter. Specifically, the metabolic response of the heterotrophic marine bacterium, Ruegeria pomeroyi, to the algal metabolite dimethylsulfoniopropionate (DMSP) was analyzed using targeted and untargeted metabolomics. The manner in which DMSP causes R. pomeroyi to modify its biochemical pathways suggests anticipation by R. pomeroyi of phytoplankton-derived nutrients and higher microbial density. Targeted metabolomics was used to characterize the latitudinal and vertical distributions of particulate and dissolved metabolites in samples gathered along a transect in the Western Atlantic Ocean. The assembled dataset indicates that, while many metabolite distributions co-vary with biomass abundance, other metabolites show distributions that suggest abiotic, species specific, or metabolic controls on their variability. On sinking particles in the South Atlantic portion of the transect, metabolites possibly derived from degradation of organic matter increase and phytoplankton-derived metabolites decrease. This work highlights the role DMSP plays in the metabolic response of a bacterium to the environment and reveals unexpected ways metabolite abundances vary between ocean regions and are transformed on sinking particles. Further metabolomics studies of the global distributions and interactions of marine biomolecules promise to provide new insights into microbial processes and metabolite cycling.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2017
Suggested CitationThesis: Johnson, Winifred M., "Linking microbial metabolism and organic matter cycling through metabolite distributions in the ocean", 2017-02, DOI:10.1575/1912/8684, https://hdl.handle.net/1912/8684
Showing items related by title, author, creator and subject.
The sediments and stratigraphy of the East Coast continental margin : Georges Bank to Norfolk Canyon Stetson, Henry C. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1949-08)The continental shelf off the northeastern coast of the United States was the first of our offshore coastal areas to be charted in detail by the Coast and Geodetic Survey, starting on Georges Bank in 1930. The techniques ...
Baringer, Molly O. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1993-10)Hydrographic and expendable current profiler (XCP) data taken during the Gulf of Cadiz Expedition in September 1988 are analyzed to diagnose the mixing and dynamics of the Mediterranean outflow. The overall structure of ...
Chen, Changsheng (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1989-09)A triangular CTD/ADCP survey was made across the Kuroshio west of Kyushu aboard the R/V Thompson during January, 1986 in order to investigate the water properties and flow field in the Kuroshio. A similar CTD survey was ...