Jasmine Berg
Department of Earth and Planetary Sciences
Washington University in St. Louis
Advisor: Dr. Jan Amend

Abstract
Hydrothermal systems have been implicated in origin of life theories and may host some of Earth's most primitive organisms. Studies of these extreme environments can help to provide a context for the origin of life, to determine the chemical and physical limits to life, and to evaluate the compatibility of life on other planets. This study uses culture-independent methods to analyze the microbial community in the white mats at Hot Lake, a hydrothermally-influenced, shallow-sea, submarine brine pool. Phylogenetic trees based on the genetic comparison of 16S rDNA extracted from environmental samples show that the Hot Lake microbial mat diversity is dominated by sulfur-metabolizing bacteria, and some thermophilic and hyperthermophilic archaea are also present. Overall, the data show that the microbiology is intricately tied to the geochemistry of Hot Lake; elemental sulfur filaments in the white mats are likely biologically precipitated as part of a microbially-mediated sulfur cycle. Future investigations using quantitative approaches and culturing can help better assess the microbial abundances, community structure, and metabolic activities at Hot Lake.