BIODIVERSITY OF BACTERIA AND ARCHAEA IN NEVADA HOT SPRINGS

Numerous hot springs are located in Nevada; some of them have extremely high pHs (>8.0). Waters in these hot springs come from geological formations that are rich in reduced inorganic energy sources. Despite the unique geological and chemical settings, the microbiology in these hot springs is essentially unexplored. The long-term goal of this study is to determine the diversity, ecological function, and evolutionary pathways of novel microorganisms in Nevada hot springs. We address these questions using an integrated approach of molecular DNA, lipid biomarkers, and stable carbon isotopes. Mat materials have been collected from several Nevada hot springs with different temperatures and pHs. The three hot springs reported here include Eagleville (40C, pH 9.2, alkalinity 55 ppm), Paradise Valley (55C, pH 6.5, alkalinity 850 ppm), and Crescent Valley (58C, pH 6.0). Bacterial fatty acids in these mats are dominated by 16:0, 18:1, and 16:1, which decrease with increasing temperatures from the Eagelville to the Crescent Valley. This indicates temperature is a major control on the distribution of bacterial fatty acids in microbial populations. PCR products from these mats indicate strong signals for Bacteria and Crenarchaeota. The presence of Crenarchaeota in the alkaline mat of Eagleville is particularly significant as all thermophilic Crenarchaeota have been isolated from acidic hydrothermal vents or geothermal springs. These results indicate that the Nevada hot springs may harbor a unique microbial community that has yet to be characterized. This study may also help fill a significant gap in our understanding of microbial diversity and functions in natural environments.