Bacterial Exopolysaccharides from the Polar Regions: an environmental-friendly microbial strategy for bioremediation and cryopreservation uses

The great metabolic and physiological capabilities of extremophilic microorganisms adapted to the cold are widely recognized and supported by numerous studies (Finore et al., 2019). Survival strategies in such harsh environments include the biosynthesis of extracellular polymeric substances (EPSs), adopted by a number of psychrophilic bacteria to cope with extremely low temperatures by protecting microbial cells from the direct contact with the surrounding cold environment (Poli et al. 2017). The ecological roles played by bacterial EPSs in natural environments could find applications in diverse biotechnological fields. EPS production falls within the scope of bioprospecting, where the investigation of new or scarcely explored biological matrices - which could be cold-adapted bacteria is of fundamental importance. This is particularly true given the current extremely urgent need to find new and safety compounds with biotechnological relevance. EPS production by psychrophilic microorganisms has been investigated during recent years, due to the wide versatility, the considerable application possibilities in a wide number of industrial fields, and the ecological and protective roles that such molecules play in microorganisms (Finore et al., 2014). Nevertheless, cold-adapted marine bacteria from several Arctic and Antarctic matrices (e.g. sediment, sea-ice and sponges, lakes) have seldom been explored as a source of EPSs. Ongoing research focusing on polysaccharides produced by extremophiles, isolated from Arctic and Antarctic regions, will be reported including chemical structures, fermentation technology and biotechnological application. In particular, the description of psychrophilic bacteria from permafrost thaw ponds (thermokarst lakes) in the Sasapimakwananisikw River valley near Kuujjuarapik-Whapmagoostui, in subarctic Québec (Canada), will be described with special attention to Pseudomonas extremaustralis strain 2ASCA, producing a levan polysaccharide with cryoprotective capability. Moreover, extracellular polymeric substances produced from sponge-associated Antarctic bacteria (belonging to Winogradskyella, Colwellia and Shewanella genera) and a Pseudoalteromonas sp. MER144, isolated from Antarctic seawater in Terra Nova Bay, will be described for chemical composition and heavy metal adsorption proprierties.