Cold Adaptation Strategy of the Antarctic Cyanobacterium P. priestleyi ULC007

In Antarctica, Cyanobacteria are key primary producers and play a major role in the colonization of deglaciated habitats. Cyanobacterial mats are widespread in aquatic biotopes and often dominate the total phototrophic biomass. In order to gain further insights on the mechanisms underlying the ecological success of Antarctic cyanobacteria, we studied the gene repertoire of Phormidesmis priestleyiULC007, a filamentous cyanobacterium isolated from shallow freshwater lake microbial mats in the Larsemann Hills. Here, we investigate the occurrence of genes involved in the cold stress response as a proxy to the adaptation to environmental conditions in Antarctica. We compare a selection of 42 PEGs (protein encoding genes) linked to cold adaptation in 72 cyanobacterial genomes. Polar strains have the highest number of copies of genes coding for fructose aldolase, chaperone Hsp, and universal stress protein and a high number of fatty acid desaturase and genes involved in exopolysaccharide (EPS) biosynthesis. To provide a better overview of the genetic mechanisms of adaptation to cold, we investigated the gene functional categories based on the RAST subsystems technology. Polar strains have the most occurrences for subsystems “Choline and Betain Biosynthesis”, “DNA repair”, “EPS biosynthesis” and “Heat shock DnaK gene cluster”. Our results underline the importance of these functions in the adaptation mechanisms of cyanobacteria to the polar environment.