There are a multitude of factors which affect both the growth and distribution of marine microbial environments, such as nutrient availability, salinity levels, temperature, and light. In Antarctic marine environments, microbes are exposed to extreme conditions, which further affect the community composition. In this project, we have analyzed the effect that different salt concentrations have on bacterial communities in Antarctica’s Lake Bonney. Cultures were obtained from a depth of 15 meters, in which the environment is observed to be both mesotrophic and under high salt concentrations. In addition, we aimed to understand how planktonic and attached communities differed in their growth and diversity under the high salt and mesotrophic conditions. Physiological and growth measurements were taken, and sequencing was done in order to obtain the experimental results. Results revealed there to be a decrease in community diversity as salt concentrations were increased. Relative abundance was calculated, which revealed that Flavobacterium presence increased with salinity levels. Furthermore, the absolute abundance of 16S rRNA gene copies were calculated in order to determine the effect of salinity concentrations on growth. Experimental results may suggest an increased likelihood of some genera to be planktonic or attached. Additionally, it is possible that there is an increased survivability of some genera in high salt conditions due to a symbiotic relationship. Further directions for research will involve determining the cause of variability between genera in both planktonic and attached communities.
Author(s): Ally Moore, Microbiology Major
Emily Hoover, Microbiology and Premedical Studies Major
Advisor(s): Rachael Morgan-Kiss, Department of Microbiology
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