02343nas 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

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 (p = 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.

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

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' 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.

10abacteria10abiogeochemical cycling10afunction10ametagenomics10avirus1 aRobinson, David, M.1 aTakacs-Vesbach, Cristina, D. uhttps://www.proquest.com/docview/311991058502038nas 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

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 inā€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 (<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.

10aAntarctica10aextremophiles10afunctional groups10ametagenomics10aprotozoa10asoil microbiology1 aThompson, Andrew, R.1 aGeisen, Stefan1 aAdams, Byron uhttps://sfamjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1462-2920.15198