@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} } @article {4962, title = {The underground network: Facilitation in soil bacteria}, journal = {Oikos}, year = {2024}, month = {06/2024}, abstract = {

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.

}, keywords = {LTER-MCM, bacteria, climate change, facilitation, resilience, stress-gradient hypothesis}, issn = {0030-1299}, doi = {10.1111/oik.10299}, url = {https://nsojournals.onlinelibrary.wiley.com/doi/10.1111/oik.10299}, author = {Jorna, Jesse and Adams, Byron J. and Aanderud, Zachary T. and Frandsen, Paul B. and Cristina D. Takacs-Vesbach and K{\'e}fi, Sonia} }