CULTURE-INDEPENDENT ANALYSIS OF MICROBIAL BIOFILMS FROM TRAVERTINE HOT SPRINGS NEAR THE VALLES CALDERA VOLCANIC COMPLEX, NEW MEXICO

Soda Dam is a travertine structure located in Northern New Mexico, near the town of Jemez Springs and 16 km southwest of Valles Caldera National Preserve. The structure began forming about 7,000 years ago from volcanically-influenced waters from the nearby Valles Caldera hydrothermal system, and is one of several similar hot springs in the region. The structure is formed by calcium carbonate rapidly precipitating out of solution, creating bands of thin mineral layers. Microorganisms form brightly colored biofilms at the orifices of geothermal seeps emanating from the travertine structure, where groundwaters are first exposed to oxygen and sunlight. Extremophilic microorganisms that thrive in these extreme environments are important for biogeochemical cycling and mineral precipitation and dissolution in volcanically-influenced systems, and represent valuable analogs for the search for life on other planets such as Mars. However, we know little about the microbial communities in the carbonate hot springs in the greater Valles Caldera ecosystem. In order to analyze the types of microorganisms present at Soda Dam, a diverse selection of biofilms, sediment, and water from several of the natural emergent springs was collected. Geochemical analysis of the aqueous samples showed a range of pH from 6.2 to 7.3 and temperature ranged from 31℃ to 43.7℃. Dissolved hydrogen sulfide concentrations ranged from 2µM to 25µM. We extracted DNA and then amplified the “hypervariable” V4 region of the 16S rRNA gene using polymerase chain reaction (PCR). Preliminary amplicon analysis has shown Thiofaba, Thiothrix and Sulfurovum to be the dominant taxa in Soda Dam springs. We will report on these as well as new rRNA gene libraries to expand our dataset to capture a larger number of samples and geochemical conditions. This information will be used in combination with fluorescent microscopy and other culture-independent data to explore microbial metabolisms, survival, and diversity and begin to evaluate how these organisms affect sulfur cycling and other chemolithotrophic processes in the travertine springs.