| Summary: | Background: In aquatic environments, microbial biofilms are hot spots of microbial diversity, as well as a substrate for larval settlement of many invertebrate species. Examining the functional diversity of microorganisms in polar regions is a new and still unknown field of aquatic microbiology, that is attracting increasing interest for its significance in both scientific research and resources exploitation. The context and purpose of the study: In the framework of research aimed at studying microbial colonization occurring at Terra Nova Bay, culturable heterotrophic bacteria were quantified and characterized phenotypically at two study areas (Road Bay and Tethys Bay) with different environmental characteristics: the first one was close to Mario Zucchelli research station and impacted by anthropogenic pressure due to sewage wastes, while the second was exposed to salinity gradients due to glacier melting. In this context, artificial structures hosting plastic (polyvinyl chloride, PVC and polyethylene, PE) panels were deployed at -5 and -20m depths at each of the stations (one Impact and one Control) chosen per each study area. Water samples were contextually collected at the time of recovery of the plastic panels, namely after 12 months of deployment; at Road Bay, at the -5 m depth, a short-term experiment was also performed, with the recovery of the panels after 2.5 and 9 months of deployment. Bacterial strains were isolated in axenic culture both from water and biofilm matrices, and examined for their main phenotypical traits and functional diversity, through Gram staining, oxidase production, glucose fermentation and screened for enzymatic activity profiles (proteolytic, glycolytic and phosphatasic activities) using specific fluorogenic substrates. Results: Most of the bacterial isolates were Gram-negative, oxidase-positive and glucose-fermenting strains. Higher enzyme diversification was found in Road Bay at the site impacted by the sewage wastes from the research station, compared to the control site. A ...
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