Lake Bonney is a saline Antarctic lake inhabited by a diverse microbial community. Algae are key members of the community and often have a sizable associated population of heterotrophs, providing them with more accessible organic carbon. The community is stratified throughout the water column, especially along the strong shifts in salinity (the chemocline) beginning 15 meters down. Examining how the salinity stratifies the community is key to understanding both how the community adapts to the extremophilic conditions of the lake, and how it will be impacted by the changes in lake salinity brought on by the lake’s melting ice cover as climate change progresses. Samples were taken from the chemocline at 15 meters and grown into enrichment cultures. These enrichment cultures were grown for 2 weeks in autotrophic media, 50% L1, 50% seawater, with either 0, 200, 500, or 750 mM NaCl and monitored for algal growth. Samples were then size fraction filtered and DNA was extracted and purified for qPCR and Metagenomic sequencing. It was found that in general, enrichment cultures grown at lower salinities grew more rapidly than those at higher salinity. This trend was also seen in qPCR data. As salinity increased, community diversity greatly decreased, except at 200mM NaCl. In 0.5 and 0.1 μm filtered samples, orders that were attached fared better than those in the planktonic sample. This led to the conclusions that stress not only decreases diversity, but also favors attached communities.
Author(s): Dom Marichal, Microbiology Major
Kaylie Wheeless, Microbiology Major Advisor(s): Rachael Morgan-Kiss, Department of Microbiology
Bradley Kryziak, Department of Microbiology Rochelle Pereira, Department of Microbiology
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