ECIMMEE Project: Quantifying microbial activity in the deep sea using NanoSIMS
The deep sea, also known as the dark ocean, is one of the largest habitats for microbial life on the planet: it covers nearly two thirds of the Earth’s surface and harbors approximately 55 percent of all marine microorganisms. Although severely understudied relative to the photic zone, the activity of deep microbial life plays an important role in marine biogeochemical cycling. In particular, recent evidence has shown the importance of chemoautotrophic Thaumarchaea, a phylum of archaea comprising about 20 percent of all marine microbes, in the cycling of nitrous oxide and carbon dioxide, both greenhouse gases. Our knowledge of the diversity and distribution of microorganisms in the deep sea has expanded in recent years with the development of next generation sequencing (i.e., “-omics”) methodologies. However, our understanding of microbial activity in the deep sea, including its phylogenetic and physicochemical controls, is still lacking. Closing this gap in our knowledge will increase our understanding of greenhouse gas cycling in the marine environment, and will better equip us to predict the activity of deep-sea microorganisms in a changing climate. This project will develop and utilize new methods to use nanoscale secondary ion mass spectrometry (NanoSIMS) — a tool to measure the isotopic composition of individual, uncultured cells — to quantify and characterize microbial activity in deep ocean waters. Combined with metagenomic and metatranscriptomic analyses, this work will link geochemical and molecular datasets, and specifically address the role of Thaumarchaea in deep-sea biogeochemical cycling.
Anne Dekas is an Assistant Professor at Stanford University in the Earth System Science Department, studying the microbiology and biogeochemistry of the deep sea. She is broadly interested in how microbial life affects the chemistry and climate of the planet, today and throughout time. Her research combines tools from molecular biology and isotope geochemistry to identify and quantify microbial metabolic capabilities, activity and interactions, with a focus on understanding uncultured microorganisms in deep-sea water and sediment. Before joining the faculty at Stanford, she was a Lawrence Postdoctoral Fellow at Lawrence Livermore National Laboratory in the Chemical Sciences Division, where she investigated the carbon metabolic flexibility of pelagic marine archaea. She received a Ph.D. in Geobiology from the California Institute of Technology for her research on nitrogen fixation, methane oxidation and sulfate reduction at deep-sea methane seeps. She received an A.B. in Earth and Planetary Sciences from Harvard University on the Biogeochemistry track. Originally interested in space sciences, Dekas performed research at three NASA centers (Jet Propulsion Laboratory, Ames Research Center and Goddard Space Flight Center) before beginning her Ph.D., and she continues to be interested in the survival strategies of life in extreme environments.