This study was intended to identify the impact of salt concentrations on the diversity of Antarctic microbial taxa. Lakes in the McMurdo Dry Valley(MDV) of Antarctica are permanently covered with 3-5 meters of ice and have substantially increasing salt concentrations as the depth increases in the lakes. Salinity is a harsh stressor for most organisms so it is important to analyze both the community structure and physiology of the microorganisms in these environments. The most prevalent microorganisms in Lake Bonney are algae and heterotrophic bacteria and these bacteria can sometimes be attached to the algae. Looking at the difference in interactions between bacteria and algae at varying salt concentrations can give valuable insight into community structure in these lakes. Samples were collected from Lake Bonney at 15 meters below the ice sheet to set up enrichment cultures. PCR and qPCR techniques were then used to amplify and quantify the organisms in the cultures to determine the taxonomy and distribution of groups. In both planktonic and attached communities, Flavobacteriales were most successful in the highest salt concentrations. The diversity of groups also dropped as salinity increased, as only specialists survived. Sphingomonadales and Betaproteobacteriales tended to be planktonic while Campylobacterales were more commonly attached. The qPCR data shows substantial variation in bacterial concentrations in each sample indicating no clear trend tied to salt concentrations.
Author(s):
Benjamin Nagle, Microbiology Major
Jaanak Patel, Microbiology and Biology Major
Advisor(s): Rachael Morgan-Kiss, Department of Microbiology