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Nancy H. Akerman
Washington University
Advisor: Jan P. Amend
Abstract
The shallow-sea hydrothermal system located in Tutum Bay, off of Ambitle Island in Papua New Guinea, presents an ideal system for investigating how microbial species are able to exist in extreme environments due to the high arsenic concentration (up to 950 ?g/L) in the vent fluids. In this study, we constructed archaeal 16S rRNA clone libraries from bulk DNA extracted from 5 sites in the Bay to investigate how microbial community composition changed at different sites. Analyses revealed members of the Crenarchaeota and Euryarchaeota, as well as a Korarchaeota-type sequence. All sites were dominated by 1 phylotype of uncultured Crenarchaeota, except for the 30 m site where ~50% of the community consisted of 1 phylotype of uncultured Euryarchaeota. We also investigated the energy that microbial species are able to gain from catalyzing redox reactions that involve inorganic species of arsenic, iron, nitrogen, and sulfur. We evaluated the Gibbs free energy of 19 potential chemolithotrophic metabolic reactions by combining environmental analyses with thermodynamic data and found that the reactions release from ?0.17 kJ/mol e- to as much as ?94.15 kJ/mol e- of energy on average. By studying the life and energy sources present in extreme environments such as Tutum Bay, we gain a better understanding of the physical and chemical limits for life on Earth, which in turn can help us to understand the limits for life on other planetary bodies.
Nancy Akerman is a graduate student pursuing her Ph.D. in the Department of Earth and Planetary Sciences at Washington University Originally from McLean, Virginia, she has a B.S. in Physics from MIT and an M.A. in Earth & Planetary Sciences from Washington University. Nancy has always been interested in planetary science and astrobiology, and her research currently focuses on characterizing the microbial life found in extreme environments on Earth. This has led her to many interesting places, including the hot springs of Yellowstone National Park and submarine hydrothermal vents in the Aeolian Islands, off the northeast coast of Sicily, Italy. She hopes to apply her scientific background in a career that involves science policy.
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