Project: OCE-PRF Track 1 (Broadening Participation): Cryptic Sulfonate Cycling between Marine Phytoplankton and Heterotrophic Bacterioplankton

NSF Award Abstract:
Information in the form of chemicals and energy flows constantly through complex networks of marine microbes. In the surface ocean, sunlight and atmospheric carbon dioxide are captured by autotrophic unicellular phytoplankton and transformed into a vast pool of organic matter that microbes use as metabolic currencies and signaling molecules to form the basis for different trading alliances. Several little-known sulfonate compounds have recently been identified as key currencies underlying marine bacterial-phytoplankton mutualisms and appear to be widespread in coastal communities. In this project, the fellow will investigate the prevalence and role of sulfonates in marine microbial interactions and their resulting impact on the Earth's biogeochemistry. With sponsor Dr. E. Virginia Armbrust at the University of Washington, the fellow will advance professionally through interdisciplinary training in microbial ecology and marine biogeochemistry. Broadening participation activities include mentorship of an undergraduate and development of an outreach program for a local minority-serving high school where students will conduct classroom laboratory exercises using microbiological and bioinformatics concepts.

Sulfonates are produced and degraded by several important phytoplankton and heterotrophic bacterial taxa, respectively. Yet, these compounds represent a poorly understood component of the marine organic matter pool. To the extent that sulfonates account for an unquantified flux of carbon and sulfur that supports mutualisms between bacteria and phytoplankton, sulfonates represent cryptic missing links in both carbon and sulfur transformations in the ocean. In this study, the fellow will use laboratory-based approaches to examine physiological and ecological controls on sulfonate production in model phytoplankton species and field-based approaches to examine taxonomically driven dynamics of sulfonate pools in the coastal waters of Puget Sound and surrounding North Pacific. Specifically, the fellow will perform metabolic profiling of model sulfonate-producing phytoplankton taxa (Aim I) and measure spatiotemporal gradients and turnover rates of sulfonates in the ocean environment using targeted in situ metabolite surveys (II) and stable isotope incubations (III), respectively, together with transcriptomics-based identification of marine microbes that control the fate of sulfonate-derived carbon (IV). The planned experiments will provide the first intensive characterization of sulfonates in the environment in terms of their contribution to the marine organic matter pool, their taxonomically driven spatiotemporal dynamics, and their roles in ocean ecosystem interdependencies.