Microbial biogeochemical cycling of dissolved organic matter

Each year marine phytoplankton extract enormous quantities of carbon dioxide, nutrients, and minerals from the atmosphere and ocean to manufacture the proteins,

carbohydrates, and lipids needed to sustain life. Microbes continually reorganize the distribution of nutrients and minerals in seawater in response to ever changing environmental conditions, such that regional and local variations in climate yield a diverse community of phyto- and bacterioplankton that are highly tuned to their environment. At the molecular level, this diversity and tuning is expressed as the microbial community’s genome. Genes direct the synthesis of organic chemicals, and the enormous diversity we observe in microbial genomes is the source of an equally diverse suite of organic chemicals present in seawater. This dissolved organic matter (DOM) is itself a factor in shaping the microbial community and directing many biogeochemical cycles. Understanding what organic compounds are present in the environment, how they impact microbial metabolism, and why they are preserved in sediments is fundamental to our knowledge of elemental cycles in the ocean. With support from the National Science Foundation and the Gordon and Betty Moore Foundation, we are engaged in a number of projects designed to investigate the microbial biogeochemistry of organic matter cycling in seawater.

All of our research uses advanced organic chemical analysis in collaboration with other laboratories that specialize in genomic, transcriptomic, or trace metal analyses as well as mathematical modeling of biogeochemical cycles. As these projects unfold, there are many new opportunities for student research through the WHOI summer and guest student fellow programs and MIT/WHOI Joint Program in oceanography, as well as co-op partnerships with other universities. If you are interested in learning more about research opportunities in our lab, please contact us at drepeta@whoi.edu.