Linking Genomes and Geochemistry in Extreme Environments Across the Greater Valles Caldera Ecosystem, New Mexico

Valles Caldera is an active volcanic caldera in the Jemez Mountains, Northern New Mexico. Most of the caldera is within a 363 km 2 National Preserve, but the greater Valles Caldera ecosystem also includes natural and artificial hot springs such as those along the Jemez River to the south. Interactions among volcanic gases, volcanically-influenced groundwaters, and surface waters results in strong geochemical gradients, from extremely acidic surface springs, streams, and lakes where CO 2 and H 2 S-rich volcanic gases mix with surface waters, to circumneutral travertine springs formed by sulfidic, volcanically-heated groundwaters. The chemical disequilibrium that results as these volcanic gases are exposed to light and oxygen provides energy for diverse chemosynthetic microbial communities that thrive on reduced volcanic gases and contribute to the biogeochemical cycling of sulfur, carbon, and other elements. We are exploring the microorganisms and microbial biogeochemical processes in acidic, sulfidic streams and lakes in the Sulfur Springs and Alamo Canyon areas of Valles Caldera National Preserve, and at Soda Dam, a large travertine hot spring near Jemez Springs, NM. Preliminary culture-independent analysis using high-throughput 16S rRNA gene sequencing and fluorescence in situ hybridization (FISH) showed that microbial communities contain eukaryotic algae and a wide variety of known chemoautotrophic sulfur oxidizers, as well as several undescribed groups of bacteria and archaea. We will discuss how the chemical, pH and temperature gradients in the region affect the diversity and types of microorganisms present, and describe new results from a research-based class at New Mexico Tech (Metagenomic Analysis, GEOB 589-01/BIOL 589-01, Spring 2023), where we are using metagenomic sequencing to discover the metabolic capabilities of some of these novel extremophiles and explore their potential biogeochemical roles in the volcanically-influenced springs and streams.