Adaptations to extreme conditions: the strategy of the Antarctic cyanobacterium ULC007

In Polar regions, freshwater ecosystems range from cryoecosystems and ice shelf meltwater ponds to perennially ice-covered lakes where conspicuous benthic microbial mat communities constitute most of the biomass. In these mats, cyanobacteria form the matrix in which other microorganisms can live, and where they are the key primary producers and main drivers of the carbon and food webs. To provide a better understanding of the survival strategies of Polar mat-forming cyanobacteria, we investigated the genome of a strain of the widely distributed Antarctic cyanobacterium, Phormidium priestleyi ULC007. We used high-throughput sequencing technologies to investigate its geographic distribution and genome evolution. More precisely, we investigated the abundance of genes involved in cold adaptation and circadian oscillation. In cold habitats, low temperatures lead to the success of particular organisms featuring adaptations to molecular and cellular disturbances such as higher rigidity of membranes, reduction of enzyme-catalyzed reactions, and reduction of solute transport. Our main results underline the importance of functional categories of genes involved in the production of key molecules for the survival of P. priestleyi in cold conditions (e.g. synthesis of exopolysaccharides, chaperone proteins, fatty acids and phospholipids)