DISSERATION RESEARCH: Geomicrobiology of manganese oxide-depositing hot springs in Yellowstone National Park

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Manganese (Mn) is an element often overlooked with respect to its potential importance in biogeochemical cycles, metabolic processes, and the biomolecular history of the Earth. Mn undoubtedly played an important role during Earth?s transition from an anoxic to an oxic planet being the key catalyst in oxygenic photosynthesis as well as the metal cofactor for key enzymes involved in oxygen metabolism. In this project we propose to study an active Mn oxide-depositing hot spring in Yellowstone National Park (YNP) as a possible analog of early Earth. In most contemporary near neutral pH environments Mn-oxidizing microorganisms are believed to be the primary catalysts for Mn oxide formation. Such Mn-oxidizing microorganisms typically encase themselves with Mn oxide minerals producing distinct structures that may be preserved in geologic deposits. While molecular oxygen is required for Mn-oxidation, only trace amounts are needed, because the source of reduced Mn is from oxygen depleted environments. Mn oxidizing microorganisms are thus typically found in the transition zone between the oxic and anoxic regions. Preliminary results of the Ph.D. graduate student this project supports has revealed the presence of ancient and unique Bacterial lineages and the occurrence of Archaea in one of the YNP hot springs. Research will characterize this hot spring ecosystem examining the water chemistry, Mn mineral deposits, microbial mats/biofilms and microbial diversity and functionality in an effort to gain a better understanding of these novel microbial communities their metabolic basis of growth and survival in the hot spring. Approaches will employ geological, chemical, microscopic, microbiological and molecular microbial ecological methods.This research will expand our knowledge of microbial biodiversity and the evolution of life on Earth, including the evolution of oxygenic photosynthesis, and may lead to the discovery of novel metabolisms and unique enzymes of potential biotechnological application. The research may also lead to new approaches for interpreting Earth?s geological record and the formation of manganese ore deposits. The project expands the graduate student training of a Native American student in environmental chemistry, analytical electron microscopy and molecular microbial ecology including molecular methods for analyzing the entire genomes of microbial communities and their activities.