02735nas a2200325   4500008004100000022001400041245008600055210006900141260001200210490000700222520179000229653001502019653001302034653001002047653002202057653001002079100002602089700002402115700002502139700002102164700001802185700002502203700002102228700002202249700001902271700002402290700002102314700001702335856005702352       2025                        eng d  a0722-406000aA comprehensive survey of soil microbial diversity across the Antarctic continent0 acomprehensive survey of soil microbial diversity across the Anta  c02/20250 v483 a<p>Antarctic soils are unique from those found nearly anywhere else on Earth yet can still harbor a broad diversity of microorganisms able to tolerate the challenging conditions typical of the continent. For these reasons, microbiologists have been drawn to Antarctica for decades. However, our understanding of which microbes thrive in Antarctic soils and how they to do so remains limited. To help resolve these knowledge gaps, we analyzed a collection of 200 archived Antarctic soils&mdash;from Livingston Island on the Antarctic Peninsula to Cape Hallett in northern Victoria Land. We analyzed the prokaryotic and fungal communities in these soils using both cultivation-independent marker gene sequencing and cultivation-dependent approaches (microbial isolation), paired with extensive soil geochemical analyses. Our cultivation-independent analyses indicate that colder, saltier, and drier soils harbor less diverse communities of bacteria and fungi, distinct from those found in soils with less challenging conditions. We also built a culture collection from a subset of these soils that encompasses more than 50 bacterial and fungal genera, including cold-tolerant organisms, such as &lt;i&gt;Cryobacterium&lt;/i&gt; and &lt;i&gt;Cryomyces&lt;/i&gt;. By directly comparing the diversity of our cultured isolates against our cultivation-independent data, we show that many of the more abundant Antarctic taxa are not readily cultivated and highlight bacterial and fungal taxa that should be the focus of future cultivation efforts. Together, we hope that our collection of isolates, the comprehensive data compiled from the cultivation-independent analyses, and our geochemical analyses will serve as a community resource to accelerate the study of Antarctic soil microbes.</p>10aAntarctica10abacteria10afungi10amicrobial ecology10asoils1 aDragone, Nicholas, B.1 aChildress, Mary, K.1 aVanderburgh, Caihong1 aWillmore, Rachel1 aHogg, Ian, D.1 aSancho, Leopoldo, G.1 aLee, Charles, K.1 aBarrett, John, E.1 aQuandt, Alisha1 aLeMonte, Joshua, J.1 aAdams, Byron, J.1 aFierer, Noah  uhttps://link.springer.com/10.1007/s00300-025-03372-y02343nas a2200217   4500008004100000245011300041210006900154260001200223490000700235520161700242653001501859653001301874653001401887653001701901653001001918100002401928700002901952700001601981700003301997856009502030       2024                        eng d00aAntarctic lake viromes reveal potential virus associated influences on nutrient cycling in ice-covered lakes0 aAntarctic lake viromes reveal potential virus associated influen  c09/20240 v153 a<p>The McMurdo Dry Valleys (MDVs) of Antarctica are a mosaic of extreme habitats which are dominated by microbial life. The MDVs include glacial melt holes, streams, lakes, and soils, which are interconnected through the transfer of energy and flux of inorganic and organic material via wind and hydrology. For the first time, we provide new data on the viral community structure and function in the MDVs through metagenomics of the planktonic and benthic mat communities of Lakes Bonney and Fryxell. Viral taxonomic diversity was compared across lakes and ecological function was investigated by characterizing auxiliary metabolic genes (AMGs) and predicting viral hosts. Our data suggest that viral communities differed between the lakes and among sites: these differences were connected to microbial host communities. AMGs were associated with the potential augmentation of multiple biogeochemical processes in host, most notably with phosphorus acquisition, organic nitrogen acquisition, sulfur oxidation, and photosynthesis. Viral genome abundances containing AMGs differed between the lakes and microbial mats, indicating site specialization. Using procrustes analysis, we also identified significant coupling between viral and bacterial communities (<i>p</i> = 0.001). Finally, host predictions indicate viral host preference among the assembled viromes. Collectively, our data show that: (i) viruses are uniquely distributed through the McMurdo Dry Valley lakes, (ii) their AMGs can contribute to overcoming host nutrient limitation and, (iii) viral and bacterial MDV communities are tightly coupled.</p>10aAntarctica10abacteria10alimnology10ametagenomics10avirus1 aRobinson, David, M.1 aMorgan-Kiss, Rachael, M.1 aWang, Zhong1 aTakacs-Vesbach, Cristina, D.  uhttps://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1422941/full02619nas a2200205   4500008004100000245006000041210006000101260006000161300000800221490001000229520198900239653001302228653002702241653001302268653001702281653001002298100002402308700003302332856004802365       2024                        eng d00aMetagenomic analysis of Antarctic microbial communities0 aMetagenomic analysis of Antarctic microbial communities  aAlbuquerque, NM, USAbUniversity of New Mexicoc06/2024  a1360 vPh.D.3 a<p>The research presented in this dissertation focuses on microbial roles in biogeochemical cycling in Antarctic aquatic environments. The major objective of my research was to examine the impact of biotic and abiotic pressures on nutrient cycling in microbially dominated systems. I used three perennially ice covered lakes in the McMurdo Dry Valleys (MDVs) along with subglacial lakes Whillans and Mercer as natural case studies. The MDVs are located in Victoria Land, East Antarctica and have been studied since 1993 as part of the McMurdo Long Term Ecological Research Project. Viruses in the MDVs were shown to be seasonally abundant and have high infection rates. My work built upon this previous research by showing that viruses are also diverse and potentially re-direct host metabolism through auxiliary metabolic genes (AMGs). Subglacial lake Whillans and Mercer lie underneath 800 and 1100 meters of ice respectively beneath the West Antarctic Ice Sheet. Previous studies in subglacial lakes Whillans have shown an active prokaryotic community. Through viral-like particle counts, microscopy, and metagenomics, we established the presence and potential metabolic influence of viruses in both Whillans and Mercer. In MDV lakes have an extensive high-throughput DNA dataset studying microbial communities through the 16S rRNA gene. We used metagenomic sequencing within two MCM lakes at multiple depths to build upon these previous datasets by annotating metagenomically assembled genomes for functional characteristics. This project highlights the lakes&#39; vertical redox gradient, showing that dominant taxa, nutrient cycling genes, and metabolic potentials change down the water column. The MDVs serve as a biological indicator for climate change in continental Antarctica and functional changes serve as important indicators of climate change. Taken together, this dissertation shows the importance of multi-kingdom microbial function under oligotrophic conditions.</p>10abacteria10abiogeochemical cycling10afunction10ametagenomics10avirus1 aRobinson, David, M.1 aTakacs-Vesbach, Cristina, D.  uhttps://www.proquest.com/docview/311991058502601nas a2200241   4500008004100000022001400041245005900055210005400114260001200168520187700180653001302057653001902070653001702089653001502106653003102121100001702152700002102169700002602190700002302216700003302239700001702272856007002289       2024                        eng d  a0030-129900aThe underground network: Facilitation in soil bacteria0 aunderground network Facilitation in soil bacteria  c06/20243 a<p>Our understanding of the fundamental role that soil bacteria play in the structure and functioning of Earth&#39;s ecosystems is ever expanding, but insight into the nature of interactions within these bacterial communities remains rudimentary. Bacterial facilitation may enhance the establishment, growth, and succession of eukaryotic biota, elevating the complexity and diversity of the entire soil community and thereby modulating multiple ecosystem functions. Global climate change often alters soil bacterial community composition, which, in turn, impacts other dependent biota. However, the impact of climate change on facilitation within bacterial communities remains poorly understood even though it may have important cascading consequences for entire ecosystems. The wealth of metagenomic data currently being generated gives community ecologists the ability to investigate bacterial facilitation in the natural world and how it affects ecological systems responses to climate change. Here, we review current evidence demonstrating the importance of facilitation in promoting emergent properties such as community diversity, ecosystem functioning, and resilience to climate change in soil bacterial communities. We show that a synthesis is currently missing between the abundant data, newly developed models and a coherent ecological framework that addresses these emergent properties. We highlight that including phylogenetic information, the physicochemical environment, and species-specific ecologies can improve our ability to infer interactions in natural soil communities. Following these recommendations, studies on bacterial facilitation will be an important piece of the puzzle to understand the consequences of global change on ecological communities and a model to advance our understanding of facilitation in complex communities more generally.</p>10abacteria10aclimate change10afacilitation10aresilience10astress-gradient hypothesis1 aJorna, Jesse1 aAdams, Byron, J.1 aAanderud, Zachary, T.1 aFrandsen, Paul, B.1 aTakacs-Vesbach, Cristina, D.1 aKéfi, Sonia  uhttps://nsojournals.onlinelibrary.wiley.com/doi/10.1111/oik.1029902431nas a2200277   4500008004100000022001300041245008500054210006900139260001200208300001100220490000800231520163400239653001501873653001301888653001401901653001901915653001901934653001901953100001401972700001201986700002501998700002102023700001702044700001602061856007602077       2022                        eng d  a0048969700aOrganic matter distribution in the icy environments of Taylor Valley, Antarctica0 aOrganic matter distribution in the icy environments of Taylor Va  c10/2022  a1566390 v8413 a<p>Glaciers can accumulate and release organic matter affecting the structure and function of associated terrestrial and aquatic ecosystems. We analyzed 18 ice cores collected from six locations in Taylor Valley (McMurdo Dry Valleys), Antarctica to determine the spatial abundance and quality of organic matter, and the spatial distribution of bacterial density and community structure from the terminus of the Taylor Glacier to the coast (McMurdo Sound). Our results showed that dissolved and particulate organic carbon (DOC and POC) concentrations in the ice core samples increased from the Taylor Glacier to McMurdo Sound, a pattern also shown by bacterial cell density. Fluorescence Excitation Emission Matrices Spectroscopy (EEMs) and multivariate parallel factor (PARAFAC) modeling identified one humic-like (C1) and one protein-like (C2) component in ice cores whose fluorescent intensities all increased from the Polar Plateau to the coast. The fluorescence index showed that the bioavailability of dissolved organic matter (DOM) also decreased from the Polar Plateau to the coast. Partial least squares path modeling analysis revealed that bacterial abundance was the main positive biotic factor influencing both the quantity and quality of organic matter. Marine aerosol influenced the spatial distribution of DOC more than katabatic winds in the ice cores. Certain bacterial taxa showed significant correlations with DOC and POC concentrations. Collectively, our results show the tight connectivity among organic matter spatial distribution, bacterial abundance and meteorology in the McMurdo Dry Valley ecosystem.</p>10aAntarctica10abacteria10aice cores10akatabatic wind10amarine aerosol10aorganic matter1 aGuo, Bixi1 aLi, Wei1 aSantibáñez, Pamela1 aPriscu, John, C.1 aLiu, Yongqin1 aLiu, Keshao  uhttps://www.sciencedirect.com/science/article/abs/pii/S004896972203736602506nas a2200289   4500008004100000022001400041245006300055210006300118260001200181490000800193520169900201653001501900653001701915653001301932653001801945653001001963653001001973100002601983700002102009700001802030700001702048700002002065700002002085700002102105700001702126856007302143       2021                        eng d  a2169-895300aExploring the boundaries of microbial habitability in soil0 aExploring the boundaries of microbial habitability in soil  c06/20210 v1263 a<p>Microbes are widely assumed to be capable of colonizing even the most challenging terrestrial surface environments on Earth given enough time. We would not expect to find surface soils uninhabited by microbes as soils typically harbor diverse microbial communities and viable microbes have been detected in soils exposed to even the most inhospitable conditions. However, if uninhabited soils do exist, we might expect to find them in Antarctica. We analyzed 204 ice-free soils collected from across a remote valley in the Transantarctic Mountains (84&ndash;85&deg;S, 174&ndash;177&deg;W) and were able to identify a potential limit of microbial habitability. While most of the soils we tested contained diverse microbial communities, with fungi being particularly ubiquitous, microbes could not be detected in many of the driest, higher elevation soils&mdash;results that were confirmed using cultivation-dependent, cultivation-independent, and metabolic assays. While we cannot confirm that this subset of soils is completely sterile and devoid of microbial life, our results suggest that microbial life is severely restricted in the coldest, driest, and saltiest Antarctic soils. Constant exposure to these conditions for thousands of years has limited microbial communities so that their presence and activity is below detectable limits using a variety of standard methods. Such soils are unlikely to be unique to the studied region with this work supporting previous hypotheses that microbial habitability is constrained by near-continuous exposure to cold, dry, and salty conditions, establishing the environmental conditions that limit microbial life in terrestrial surface soils.</p>10aAntarctica10aastrobiology10abacteria10aextremophiles10afungi10asoils1 aDragone, Nicholas, B.1 aDiaz, Melisa, A.1 aHogg, Ian, D.1 aLyons, Berry1 aJackson, Andrew1 aWall, Diana, H.1 aAdams, Byron, J.1 aFierer, Noah  uhttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG00605202485nas a2200229   4500008004100000245009100041210006900132260001200201490000600213520181500219653001302034653002802047653001102075653001302086653001002099653002102109653002102130653002502151100001702176700002002193856004202213       2019                        eng d00aBiotic interactions in experimental Antarctic soil microcosms vary with abiotic stress0 aBiotic interactions in experimental Antarctic soil microcosms va  c08/20190 v33 a<p>Biotic interactions structure ecological communities but abiotic factors affect the strength of these relationships. These interactions are difficult to study in soils due to their vast biodiversity and the many environmental factors that affect soil species. The McMurdo Dry Valleys (MDV), Antarctica, are relatively simple soil ecosystems compared to temperate soils, making them an excellent study system for the trophic relationships of soil. Soil microbes and relatively few species of nematodes, rotifers, tardigrades, springtails, and mites are patchily distributed across the cold, dry landscape, which lacks vascular plants and terrestrial vertebrates. However, glacier and permafrost melt are expected to cause shifts in soil moisture and solutes across this ecosystem. To test how increased moisture and salinity affect soil invertebrates and their biotic interactions, we established a laboratory microcosm experiment (4 community &times; 2 moisture &times; 2 salinity treatments). Community treatments were: (1) Bacteria only (control), (2) Scottnema (<em>S. lindsayae</em> + bacteria), (3) Eudorylaimus (<em>E. antarcticus</em> + bacteria), and (4) Mixed (<em>S. lindsayae</em> + <em>E. antarcticus</em> + bacteria). Salinity and moisture treatments were control and high. High moisture reduced <em>S. lindsayae</em> adults, while high salinity reduced the total <em>S. lindsayae</em> population. We found that <em>S. lindsayae</em> exerted top-down control over soil bacteria populations, but this effect was dependent on salinity treatment. In the high salinity treatment, bacteria were released from top-down pressure as <em>S. lindsayae</em> declined. Ours was the first study to empirically demonstrate, although in lab microcosm conditions, top-down control in the MDV soil food web.</p>10abacteria10abiological interactions10adesert10anematode10apolar10asoil communities10atop-down effects10atrophic interactions1 aShaw, Ashley1 aWall, Diana, H.  uhttps://www.mdpi.com/2571-8789/3/3/5705193nas a2200229   4500008004100000245009300041210006900134260004000203490000900243520447100252653002304723653001504746653001304761653002204774653000904796653001704805653002704822653002404849100002404873700002604897856004004923       2013                        eng d00aResource Legacies and Priming Regulate Microbial Communities in Antarctica's Dry Valleys0 aResource Legacies and Priming Regulate Microbial Communities in   aProvo, UTbBrigham Young University0 vM.S.3 a<p>Multiple mechanisms control bacterial community structure but two in particular, the &quot;legacy&quot; of past environmental conditions, and the &quot;priming&quot; of bacteria to respond to seasonal or reoccurring fluctuations in resources, have the potential to determine both bacterial communities, as well as, temporal shifts in active bacterial taxa. To begin to evaluate the legacy effects of resources on microbial communities, we added four limiting resources annually (i.e., water only; C-mannitol + water; N-NH4NO3 + water; and C, N + water) and measured shifts in bacterial community composition after seven years in a cold desert ecosystem in the McMurdo Dry Valleys, Antarctica. Further, to investigate the ecological significance of priming, we conducted a series of stable isotope probing experiments (i.e., 18O-DNA SIP with 18O-labeled water, 13C-DNA SIP with 13C-labeled mannitol, 15N-DNA with 15N- NH4NO3, and a combined C and N SIP) and characterized the responding (i.e., isotopically labeled) and seed bank (i.e., unlabeled) bacterial communities. We performed each of the SIPs in soil microcosms corresponding to a single resource manipulation (e.g., 13C-labeled mannitol in C addition soils). We hypothesized that all long-term additions of nutrients and water will lead to a distinct bacterial community&mdash;a legacy effect due to the nutrient and water impoverished state of Antarctica soils. We also hypothesized that the stronger the legacy effects demonstrated by a specific community the more adapted or primed bacterial species will be to take advantage of the resource and respond. As hypothesized, resource additions created distinct bacterial legacy but to different degrees among the treatments. The extent of the resource legacy effects was greatest in the CN, intermediate in water and N, and lowest in C communities relative to the control communities, suggesting that C induced changes in communities were intensified by tandem N additions and that water alone created a more distinct legacy than water and C additions combined. Contrary to our hypothesis, the stronger the legacy effects, the less adapted or primed the community was to take advantage of resource additions. For example, the CN treatment that induced the greatest effect on bacterial communities had the lowest number of species (20.9%) in common between the responding and seed bank communities. This inverse relationship may be due to only two species (i.e., Arthrobacter, Actinobacteria and Massilia, Betaproteobacteria) really being primed to take advantage of CN and these species constituting over 75% of the seed bank community. Water, N, and C additions had similar levels of priming with 38.4%, 41.4%, and 36.3% of the responding species being present in the seed bank community, respectively. But of these three treatments, only the priming with water resulted in a unique responding community, suggesting that water, a universal bacterial resource, was enough to prime bacteria. Furthermore, water generates the most diverse responding community of all the resources with stemming from all of the fourteen dominant phyla. We did find patterns of ecological coherence among the responders, especially in the major responders (i.e., responders that increased in relative recovery by at least ten-fold). These responders were predominantly found in only three phyla (i.e., Actinobacteria, Bacteriodetes, and Gammaproteobacteria) regardless of resource addition. Alternatively minor responders (i.e., responders that increased in relative recovery at least two-fold) were contained in fourteen different phyla with specific taxa stimulated by CN (i.e., Betaproteobacteria) and N and water (i.e., Deltaproteobacteria). Further, resource additions elicited responses from 37% of bacterial species with species specializing on a specific resource (e.g., Chloroflexi) or being a generalist (e.g., Planctomycetes and Gammaproteobacteria). Our results offer the first direct links between legacy and priming effects on bacterial community composition and demonstrate that these mechanisms are not always complimentary leading to the formation of similar communities but may both be essential to maintain the high levels of bacterial diversity. Further, all resources produced elicited responders that were either specialists of generalists demonstrating that even bacteria in the extreme environment of Antarctica respond to pulses of resources.</p>10a454 pyrosequencing10aAntarctica10abacteria10amicrobial ecology10asoil10asoil ecology10astable isotope probing10atarget metagenomics1 aSaurey, Sabrina, D.1 aAanderud, Zachary, T.  uhttp://hdl.lib.byu.edu/1877/etd6229