@article {4998, title = {Antarctic lake viromes reveal potential virus associated influences on nutrient cycling in ice-covered lakes}, journal = {Frontiers in Microbiology}, volume = {15}, year = {2024}, month = {09/2024}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, bacteria, limnology, metagenomics, virus}, doi = {10.3389/fmicb.2024.1422941}, url = {https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1422941/full}, author = {Robinson, David M. and Rachael M. Morgan-Kiss and Wang, Zhong and Cristina D. Takacs-Vesbach} } @phdthesis {5018, title = {Metagenomic analysis of Antarctic microbial communities}, volume = {Ph.D.}, year = {2024}, month = {06/2024}, pages = {136}, school = {University of New Mexico}, type = {doctoral}, address = {Albuquerque, NM, USA}, abstract = {

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.

}, keywords = {LTER-MCM, bacteria, biogeochemical cycling, function, metagenomics, virus}, url = {https://www.proquest.com/docview/3119910585}, author = {Robinson, David M.}, editor = {Cristina D. Takacs-Vesbach} } @mastersthesis {4441, title = {Microbial and CO2 responses to water stresses show decreased productivity and diversity through time}, volume = {M.S.}, year = {2018}, month = {05/2018}, school = {Brigham Young University}, type = {masters}, address = {Provo, UT}, abstract = {

Some bacterial taxa when stimulated by water additions will break dormancy, grow, and become dominant members of the community and contribute significant pulses of\ CO2 associated with the rewetting event. These pulses of activity are associated with high levels of bacterial productivity in soils. (Aanderud et al. 2011) We examined the bacterial taxa that resuscitate and become metabolically active following two forms of water stress (soil drying- rewetting and freeze-thaw cycles) and we captured and measured the CO2 emanating from those soils. Specifically, We used target metagenomics, which uses a specific gene pool within bacteria that is associated with a function of an ecological process, in this case active (16S rRNA communities) bacteria and all bacteria (16S rRNA communities) during drying-rewetting and freeze-thaw cycles. We measured an array of community dynamics (i.e., evenness, richness, diversity, relative abundance of taxa, and network analyses between taxa) as dry soils are rewetted and as frozen soils thaw multiple times in three cold desert soils. Soils from all three locations exhibited some similar bacterial taxa and gene function but were large in part their own community derived from the evolutionary history of the continent in which they reside.

}, keywords = {LTER-MCM, dormancy, PiCRUST, turnover}, url = {https://scholarsarchive.byu.edu/etd/6830}, author = {Robinson, David M. and Aanderud, Zachary T.} }