LEXEN: Growth Media for Hyperthermophiles: Geochemical Constraints on Realistic Carbon and Energy Sources in Shallow Marine Hydrothermal Systems

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9714288 Amend PROJECT SUMMARY The isolation and characterization since 1980 of several dozen species of hyperthermophilic microorganisms are largely responsible for the tremendous current interest in life in extreme environments on Earth as well as on other planetary bodies in our solar system. Most known hyperthermophiles were cultured from rock and water samples collected at deep submarine hydrothermal vents or terrestrial hot springs. Although much has been learned about microbial physiologies, phylogenetic diversity, and novel metabolic pathways from this relatively sparse set of organisms, the true extremes of genetic diversity and metabolic strategies on Earth and elsewhere are impossible to predict a priori. This concept is underscored by the widely accepted notion that less than 0.1 percent of all extant microbial species are currently known. Knowledge of microbial species thriving in extreme environments can be expanded through the application of innovative methods to isolate and culture novel species of extremophiles. Like all living organisms, hyperthermophiles are intimately associated with their host environment. Therefore, a detailed understanding of the geochemistry of hydrothermal environments is likely to place constraints on essential substrates for life. To reach this overall goal, this project will combine thermodynamic calculations to determine potential energy sources with detailed chemical analyses of hydrothermal fluids to design new media for growing a wide variety of hyperthermophiles. The readily accessible and chemically diverse hot springs in the Aeolian Islands, Italy, including those on Vulcano, are ideal sampling sites for this highly interdisciplinary study.