First insights on the microbiology of three Antarctic briny systems of the Northern Victoria Land

Different polar environments (lakes, glaciers), also in Antarctica, may encapsulate brine pools characterized by a unique combination of extreme conditions, mainly in terms of high salinity and low temperature. Since 2014, we are focusing our attention on the microbiology of brine pockets from three lakes in the Northern Victoria Land (NVL), lying in the Tarn Flat (TF) and Boulder Clay (BC) areas. Microbial communities were analyzed for community structure by next generation sequencing, extracellular enzyme activities, metabolic potentials and microbial abundances. This paper aims at reconsidering all available data to analyzethe influence exerted by environmental parameters on the community composition and activities. Additionally, the prediction of metabolic functions was attempted by the Phylogenetic Investigation of Communities by Re-construction of Unobserved States (PICRUSt2) tool, highlighting that prokaryotic communities were presumably involved in methane metabolism, aromatic compounds biodegradation and organic compounds (proteins, polysaccharides, phosphates) decomposition. The analyzed cryo-environments were different in terms of prokaryotic diversity, abundance and retrieved metabolic pathways. By the analysis of DNA sequences, common operational taxonomic units ranged from 2.2 to 22.0%. The bacterial community was dominated by Bacteroidetes. In both BC and TF brines, sequences of the most thermally tolerant and methanogenic Archaea were detected, some of them related to hyperthermophiles.