02600nas a2200217   4500008004100000245010600041210006900147260001200216490000700228520191500235653001502150653001802165653001602183653002202199653001702221100002202238700001702260700002102277700001702298856006702315       2021                        eng d00aAntarctic water tracks: Microbial community responses to variation in soil moisture, pH, and salinity0 aAntarctic water tracks Microbial community responses to variatio  c01/20210 v123 a<p>Ice-free soils in the McMurdo Dry Valleys select for taxa able to cope with challenging environmental conditions, including extreme chemical water activity gradients, freeze-thaw cycling, desiccation, and solar radiation regimes. The low biotic complexity of Dry Valley soils makes them well suited to investigate environmental and spatial influences on bacterial community structure. Water tracks are annually wetted habitats in the cold-arid soils of Antarctica that form briefly each summer with moisture sourced from snow melt, ground ice thaw, and atmospheric deposition via deliquescence and vapor flow into brines. Compared to neighboring arid soils, water tracks are highly saline and relatively moist habitats. They represent a considerable area (&sim;5&ndash;10 km<sup>2</sup>) of the Dry Valley terrestrial ecosystem, an area that is expected to increase with ongoing climate change. The goal of this study was to determine how variation in the environmental conditions of water tracks influences the composition and diversity of microbial communities. We found significant differences in microbial community composition between on- and off-water track samples, and across two distinct locations. Of the tested environmental variables, soil salinity was the best predictor of community composition, with members of the <em>Bacteroidetes</em> phylum being relatively more abundant at higher salinities and the <em>Actinobacteria</em> phylum showing the opposite pattern. There was also a significant, inverse relationship between salinity and bacterial diversity. Our results suggest water track formation significantly alters dry soil microbial communities, likely influencing subsequent ecosystem functioning. We highlight how Dry Valley water tracks could be a useful model system for understanding the potential habitability of transiently wetted environments found on the surface of Mars.</p>10aAntarctica10aextremophiles10aMars analog10amicrobial ecology10awater tracks1 aGeorge, Scott, F.1 aFierer, Noah1 aLevy, Joseph, S.1 aAdams, Byron  uhttps://www.frontiersin.org/articles/10.3389/fmicb.2021.61673002038nas a2200205   4500008004100000245010100041210006900142260001200211520136000223653001501583653001801598653002201616653001701638653001301655653002201668100002501690700001901715700001701734856008101751       2020                        eng d00aShotgun metagenomics reveal a diverse assemblage of protists in a model Antarctic soil ecosystem0 aShotgun metagenomics reveal a diverse assemblage of protists in   c08/20203 a<p>The soils of the McMurdo Dry Valleys (MDV) of Antarctica are established models for understanding fundamental processes in soil ecosystem functioning (e.g. ecological tipping points, community structuring, and nutrient cycling) because the extreme physical environment drastically reduces biodiversity and ecological complexity. Understanding the functioning of MDV soils requires in‐depth knowledge of the diversity of MDV soil species. Protists, which contribute significantly to soil ecosystem functioning worldwide, remain poorly characterized in the MDV. To better assess the diversity of MDV protists, we performed shotgun metagenomics on 18 sites representing a variety of landscape features and edaphic variables. Our results show MDV soil protists are diverse at both the genus (155 of 281 eukaryote genera) and family (120) levels, but comprise only 6% of eukaryotic reads. Protists are structured by moisture, total N, and distance from the local coast, and possess limited richness in arid (&lt;5% moisture) and at high elevation sites, known drivers of communities in the MDV. High relative diversity and broad distribution of protists in our study promotes these organisms as key members of MDV soil microbiomes and the MDV as a useful system for understanding the contribution of soil protists to the structure of soil microbiomes.</p>10aAntarctica10aextremophiles10afunctional groups10ametagenomics10aprotozoa10asoil microbiology1 aThompson, Andrew, R.1 aGeisen, Stefan1 aAdams, Byron  uhttps://sfamjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1462-2920.15198