The microbial diversity at the few confirmed geothermal sites in Antarctica, which include sites in Marie-Byrd Land and three volcanoes in Victoria Land, has been poorly studied ( Broady et al., 1987 Bargagli et al., 2004 Soo et al., 2009 Herbold et al., 2014a). Polar and subpolar geothermal sites include those in Iceland, Kamchatka, continental Antarctica, and sub-Antarctic islands such as Deception Island and the Sandwich Islands ( Boyd et al., 1990 Marteinsson et al., 2001 Herbold et al., 2014b Mardanov et al., 2018). Studies of the impact of geothermal activity on microbial diversity in polar regions are limited, as these areas are often remote and difficult to access. These gradients provide opportunities to examine how physicochemical parameters affect microbial community structures ( Nakagawa and Fukui, 2002 Norris et al., 2002 Miller et al., 2009) and to explore microbial strategies for growth in these conditions ( Takacs-Vesbach et al., 2013 Weltzer and Miller, 2013 Beam et al., 2014). Gradients in physicochemical parameters are commonly formed at the transition between isolated surface geothermal features and the surrounding non-geothermal environment. Terrestrial geothermal sites, distributed across the planet, are characterized by features such as hot springs, fumaroles, geysers, and localized hot soil sites ( Inskeep et al., 2013 Mardanov et al., 2018 Power et al., 2018). The extreme selective pressures at geothermal sites drive the evolution of unique metabolic pathways and physiological adaptations in the resident microflora, challenging our perception of the limits of life ( Fields, 2001 Belilla et al., 2021 Mueller et al., 2021). Geothermal areas are dominated by microscopic life capable of thriving under extreme physicochemical conditions ( Shu and Huang, 2021). Erebus to better understand this unique environment. These analyses highlight the importance of conducting broader-scale metagenomics and cultivation efforts at Mt. Based on the known metabolic capabilities of previously studied members of these groups, we predict that chemolithotrophy is a common strategy in this system.

ASVs assigned to Chloroflexi classes Ktedonobacteria and Chloroflexia were detected at both sites. A co-occurrence network, paired with physicochemical analyses, allowed for finer scale analysis of parameters correlated with differential abundance profiles, with various parameters (total carbon, total nitrogen, soil moisture, soil conductivity, sulfur, phosphorous, and iron) showing significant correlations. The abundance profiles of several microbial groups were different between the two sites class Nitrososphaeria amplicon sequence variants (ASVs) dominated the community profiles at Tramway Ridge, whereas Acidobacteriotal ASVs were only found at Western Crater. Notably, pH, not temperature, showed the strongest correlation with these differences. We found distinct soil compositions between the two sites, and to a lesser extent within Tramway Ridge, correlated with disparate microbial communities. Samples were collected along three thermal gradients, one from Western Crater and two within Tramway Ridge, which allowed an examination of the heterogeneity present at Tramway Ridge. Erebus: Tramway Ridge, a weather-protected high biomass site, and Western Crater, an extremely exposed low biomass site. Using 16S rRNA gene amplicon sequencing and physicochemical analyses, we compared samples collected at two contrasting high-temperature (50☌–65☌) sites on Mt. Erebus, Antarctica, is the world’s southernmost active volcano and is unique in its isolation from other major active volcanic systems and its distinctive geothermal systems.

7Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States.

6Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States.

5School of Biological Sciences, University of Canterbury, Christchurch, New Zealand.4Faculty of Sciences, University of Porto, Porto, Portugal.3Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Matosinhos, Portugal.

2International Centre for Terrestrial Antarctic Research, University of Waikato, Hamilton, New Zealand.

1Te Aka Mātuatua-School of Science, Te Whare Wānanga o Waikato-University of Waikato, Hamilton, New Zealand.

Erebus novel