GENETIC ADAPTATIONS IN CYANOBACTERIA TO EXTREME COLD MAY INFLUENCE MICROBIALITE FORMATION IN ANTARCTIC LAKES

Environmental factors contribute to shaping the spatial ecology of ecosystems, encompassing components such as temperature, nutrient availability, population density, irradiance, etc. Worldwide, microbial mats are predominantly composed of cyanobacteria, with their morphology linked to their microbial community members. Antarctic mats exhibit diverse shapes, ranging from smooth flat surfaces to branched stromatolites and intricate honeycomb configurations. In this study, we are investigating the genetic adaptations of cyanobacteria within microbial mats found in the freshwater lakes of McMurdo Dry Valleys, Antarctica. These cyanobacteria demonstrate remarkable adaptability, thriving in temperatures below 5°C, likely due to specific adaptations to overcome cold temperature-specific challenges. This work follows prior research on the other end of the thermal spectrum on microbial mat communities in the hot springs of Yellowstone National Park, which have similar microbialite structures. Notably, there are few organisms in both hot and cold environments, and prior work shows that those in hot springs have unique two-component sense-response systems (TCS) specifically adapted to hot environments. We hypothesize that similar TCS system adaptations and other cold tolerance regulations like ensuring membrane fluidity will be found in Antarctic cyanobacteria. Understanding these, and other cold-tolerance genetic adaptations, can provide insights into the community compositions of microbial mats in cold environments.

By conducting this research, we aim to enhance our understanding of the genetic mechanisms that enable cyanobacteria to thrive in extreme-cold environments and contribute to the formation and morphology of microbial mats, including Antarctic microbialites. This knowledge can have broader implications for studying microbial communities and their adaptations in different ecosystems that allow for microbialite formation.