This project is based on the globally important function of bacterial transformation of the ubiquitous organic sulfur compound dimethylsulfoniopropionate (DMSP) in ocean surface waters. Recent genetic discoveries have identified key genes in the two major DMSP degradation pathways, and the stage is now set to identify the factors that regulate gene expression to favor one or the other pathway during DMSP processing. The taxonomy of the bacteria mediating DMSP cycling has been deduced from genomic and metagenomic sequencing surveys to include four major groups in the ocean. Understanding how the regulation of DMSP degradation differs among these groups and maps to the relationships between these groups is important information for understanding the marine sulfur cycle and predicting its function in a changing ocean. The project will incorporate the use of model organism studies, microcosm experiments (at Dauphin Island Sea Lab, AL), and time-series field studies with an autonomous sample collection instrument (at Monterey Bay, CA). This project will ascertain how the major taxa of bacterial DMSP degraders in seawater regulate DMSP transformations, and address the implications of bacterial functional, genetic, and taxonomic diversity for global sulfur cycling..
The project will train graduate students and a post-doctoral scholar in microbial biodiversity and provide research opportunities and mentoring for undergraduate students. Students will obtain interdisciplinary training in microbial ecology, sulfur chemistry/biogeochemistry, and environmental bioinformatics, and will participate in research to improve our understanding of how marine bacterioplankton regulate the global fate of sulfur. An outreach program will enhance understanding of the role and diversity of marine microorganisms in global elemental cycles among promising high school students. Advanced Placement (AP) Biology students at a racially diverse Athens, GA, high school will participate in marine microbial research that covers key learning goals in the new AP Biology curriculum. Students will conduct classroom laboratory exercises with bacterial strains isolated from coastal Georgia seawater to learn ecological, microbiological, molecular biological, and bioinformatic concepts. During an end-of-the-year field trip to Sapelo Island, students will isolate new strains that become the study organisms for the next class of AP Biology students. Two high school students will be selected for summer research internships in the laboratories of the principal investigators. The project also supports education and outreach efforts at public aquaria (DISL Estuarium and Monterey Bay Aquarium) and summer graduate courses.
