| Summary: | 16 Symposium of Aquatic Microbial Ecology (SAME16), “From Boat to Bench”- Integrating field observation with lab experiments, 1-6 September 2019, Potsdam, Germany.-- 1 page The ocean under the Ross Ice Shelf (RIS) in Antarctica is one of the least explored environments on Earth. This remote marine environment, in total darkness under hundreds of meters of ice, touched only by slow deep ocean currents, is as unexplored as Mars. Microbes are the engines that drive biogeochemical cycles and the microbes under Antarctica’s ice sheets may play a crucial role in remineralizing nutrients to the Southern Ocean. Thus, better knowledge of the roles that these microbes play in the transformation of organic matter will lead to a better understanding of the processes that control energy flow in the Southern Ocean, as well as the cycling of compounds influencing climate change. Still, we do not know which microbes live below the RIS, let alone what functions they perform. The only study in which the seawater under the RIS was studied (at the J9 borehole in 1977/78), revealed the presence of microbes together with a rich community of invertebrates and fish far away from the open ocean. However, the technology required to investigate microbial diversity was not available at that time. Forty years later, we drilled through ca. 400 m of ice shelf to reveal, for the first time, the actual structure and function of the RIS ocean microbial ecosystem. We combined rate measurements with amplicon sequencing to determine the abundance, heterotrophic activity, community composition and diversity of microbes under the RIS, together with multi-omics (metagenomic, metatranscriptomics and metaproteomics) and single amplified genomes (SAGs) to obtain a full analysis of their metabolic potential and actual gene expression and protein production. Collectively, our results revealed the mechanism supporting an active and diverse microbial ecosystem, fueled by chemolithoautotrophy and capable of obtaining their energy from a wide range of ...
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