MIP: Abundance, Diversity, and Activity of Anaerobic Propane- and Butane-Oxidizing Microorganisms at a Hydrothermal Hydrocarbon Seep

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In many ocean sediments, hydrocarbons can reach high concentrations and are potentially important substrates for microbial communities. One of the most spectacular places where large quantities of hydrocarbons are naturally introduced into the biosphere is the deep-sea hydrothermal vent site in Guaymas Basin, in the Gulf of California. Sediment cores and vent fluids will be collected for microbiological and geochemical studies from the sediment-covered hydrothermal system at Guaymas Basin. Fluorescence in situ hybridization (FISH) in combination with geochemical analyses will be performed to assess the abundance and distribution of previously enriched and isolated organisms. Furthermore, stable isotope probing (SIP) will be utilized to identify microorganisms carrying out anaerobic propane and butane oxidation in situ, and novel organisms utilizing these hydrocarbons will be enriched and isolated under a wide range of conditions. This study will determine the relationship between in situ geochemical conditions at naturally occurring hydrocarbon seeps and the abundance and distribution of anaerobic microorganisms that degrade gaseous hydrocarbons. Anaerobic biodegradation of hydrocarbons greatly expands the range of geologic environments that may support life and has profound implications for our understanding of factors that regulate life and carbon cycling on earth.Results of this investigation have direct relevance to the petroleum industry where a growing number of studies indicate the preferential degradation of propane and butane in subsurface petroleum reservoirs. Thus, a better understanding of the ecology and environmental importance of microorganisms catalyzing this process has implications for deepening our insights of biogeochemical processes in marine sediments, the terrestrial subsurface, and economically viable petroleum accumulations. Broader impacts of this project include the web-based dissemination of data, facilitating the exchange of ideas, and promoting educational and outreach activities. Undergraduate and graduate students will be trained in modern methods of microbial ecology, geobiology, and geochemistry. To further an understanding of the interactions between the biosphere and geosphere, it is becoming increasingly important to educate the future generation of scientists in a way that they are able to converse widely and conduct interdisciplinary research.