Collaborative Research: Organic Compounds in Hydrothermal Systems: A Framework for Investigating Heterotrophy at High Temperature

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ABSTRACTOCE-0221417OCE-0221113This study sets out to make chemical measurements of inorganic and organic carbon compounds found in a complex and poorly understood environment, shallow water marine hydrothermal systems. Due in part to limited sampling opportunities, our understanding of marine hydrothermal microbial systems and especially of their organic geochemistry is lacking. The metabolic energy requirements of microbial lifeforms in these environments is also unclear. Determination of the chemical structures and concentrations of a series of aqueous low molecular weight organic compounds (amino acids, carbohydrates and organic acids) will allow the modeling of the energetic bounds associated with the metabolism of these substrates by heterotrophic thermophiles. A series of studies, including using direct SCUBA field sampling of the study site (Aeolian Islands, Sicily), will allow hydrothermal vent fluid collection including temporal variation. Thermophilic bacteria are known to be metabolically opportunistic, having the capability of utilizing a variety of carbon sources present in their environment along with one or more electron acceptors. How these organisms perform such metabolic manipulations and how they dynamically adapt to changes in their chemical and physical environment is not yet known. These investigators will employ a thermodynamic modeling approach, using known concentrations of specific substrates at known temperatures, to calculate the possible bioenergetic energy yields of the respiratory and fermentative reactions these organisms use in hydrothermal environments. This in turn will increase our understanding of the biogeochemical processes that may fuel the microbial energetics in the deeper subsurface biosphere.