The microbial communities of Antarctic lakes have evolved to thrive under the extreme conditions present in their niche habitats. Ranging from low temperatures to high salinity, a number of obstacles are present which these communities must overcome to survive. We exposed enrichment cultures isolated from two different Antarctic lakes, Lake Bonney, and Lake Fryxell, as well as a pure isolate from Lake Bonney to a host of environmental stressors including high temperatures, high salinity, oxidative stress, low-light, and nutrient deficiency. We took various growth measurements and sequence the organisms present in the samples. We then sequenced 16s and 18s genes to evaluate changes in the composition of the cultures. By doing this, we hope to gain a better understanding of how the physiology and diversity of these communities change in response to environmental stressors. We found that in the mixed cultures extreme shade had the biggest impact on photosynthetic activity, while high temperature showed a larger decrease in the pure culture. Additionally, all three cultures showed resilience to oxidative stress. These changes can provide insight into how these communities may respond to natural fluctuations in conditions as well as those caused by external factors such as climate change. Furthermore, a class of green algae, Chlorophyceae was found to be most abundant in both the lakes irrespective of the stresses (shade, high temperature, high salt, oxidative stress, and nutrient deficiency). However, shades showed that the diversity of organism is slightly disturbed in comparison to the control group at the starting time point.
Authors: Bradley Krzysiak, Devon Popson, Roshan Timsina
Faculty Advisor: Rachael Morgan-Kiss, Microbiology
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