AN INTERDISCIPLINARY AND MULTINATIONAL PROGRAM TO STUDY MICROBIAL ENERGY TRANSFER AND CHEMOSYNTHETIC CARBON FIXATION AT DEEP-SEA VENTS

Deep-sea hydrothermal vents, first discovered in 1977, are ‘poster child’ ecosystems where microbial chemoautotrophy rather than photosynthesis is the primary source of organic carbon. Chemolithoautotrophic microorganisms are at the nexus of these systems by effectively transferring the energy from geothermal sources to higher trophic levels. While the validity of this conceptual framework is well established, there are still major gaps in our understanding of the microbiology and biogeochemistry of deep-sea hydrothermal systems. This includes information on the diversity of microorganisms mediating critical reactions in different geothermal systems, the metabolic pathways used by microbes, the rates of catalyzed reactions, and the amount of organic carbon being produced. In particular, there is a notable lack of quantitative and process-oriented studies to assess the larger role of these ecosystems in global biogeochemical cycles.
To address these gaps in our knowledge requires a focused, interdisciplinary, hypothesis-driven research program to characterize the complexity of microbial processes at deep-sea vents. Here, I will present the outlines and first results of a new research program that was recently funded by NSF’s new Dimensions of Biodiversity program. This project pursues an integrated approach that couples an assessment of who is there using cultivation-dependent and -independent approaches with methodologies addressing who is doing what, including a) metagenomics (genetic potential and community diversity), b) metatranscriptomics and -proteomics (identification and function of active community members, realized community potential). To assess function and response to the environment, these approaches will be combined with 1) time series measurements of chemoautotrophic production at in situ pressure and temperature using a novel Incubating Productivity System (IPS) deployed at the seafloor, 2) geochemical characterization of microbial habitats, and 3) innovative batch- and flow-through incubations under simulated in situ conditions using isobaric samplers and a flow-through reactor (hypothesis testing under controlled physicochemical conditions). The results of this study, involving PIs from eight institutions in four countries, will provide new insights into the functioning of deep-sea vent microbial communities and the constraints regulating the interactions between the microbes and their abiotic and biotic environment, ultimately enabling us to put these systems into a quantitative framework and thus a larger global context.

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First Name: 
Stefan
Last Name: 
Sievert
Telephone: 
508-2892305
Affiliation: 
Woods Hole Oceanographic Institution
Choose keywords that are most applicable to your abstract. (Three maximum.): 
Microbiology
Abstract ID: 
CBE5-124