C29: MBI575: Attachment of Bacteria to Algae as an Adaptation to Salt Stress in Antarctic Lakes

Antarctic lakes are extreme environments. Contrary to temperate lakes, they never mix and hence present a permanent stratification, following gradients of different abiotic factors such as salt that increases with depth. As the nutrients are very limiting in such environments, the biological communities are dominated by autotrophic organisms that fix the inorganic carbon and make it available for the other groups. These primary producers are mostly algae. Additionally, we can find a range of microorganisms that rely on the primary producers for their organic matter assimilation. The bacterial communities can be free in the water column (ie planktonic) or directly attached to algal cells. These close interactions are hypothetically more stable and result in stronger benefits for both algae and bacteria.
In this study we focus on how planktonic and attached bacterial communities shift when submitted to a range of salt stress treatments. We predict that the planktonic fraction will be more sensitive to stress and hence less stable than the attached fraction. This experiment is conducted on two different initial communities, one sampled in shallower and fresher water (6 m) and the other sample deeper in salty water (15).
The bacterial diversity is assessed with next generation sequencing after a size fractionation of the cultures to separate the planktonic and attached bacterial communities.
Author(s): Colin Gaillot, Microbiology Major 

Chetna Sharma, Microbiology Major 

Advisor(s): Rachael Morgan-Kiss, Department of Microbiology 

Bradley Kryziak, Department of Microbiology 

Rochelle Pereira, Department of Microbiology