Microbial diversity characterizing different depth zones inside the ice cave Cenote Abyss

Microbial life at the cryosphere represents a unique archive of peculiar and slow biogeochemical processes in ancient and chilly environmental conditions. The investigation of the geomicrobiology of ice layers of glacial locations provide clues for the past climate reconstruction and for understanding the impact of climate change on ice. Here, we provide a first description of the microbial communities inhabiting ice sediments collected at different depth inside the ice cave Cenote Abyss located on the Italian Alps. This cave was first explored in 1994 after the emptying of a lake and currently represents one of the most voluminous cave glaciers of the Dolomites. The microbial communities of Cenote Abyss were dominated by members of Actinobacteria, Bacteroidetes and Proteobacteria well adapted to extreme temperatures and possibly involved in different steps of the nitrogen cycle in accordance with the cave depth. From the shallowest to the deepest zones of the cave, the microbial community composition shifted from the dominance of nitrogen fixing bacteria, such as Parafrigobacterium, Polaromonas and Pedobacter, to the high presence of nitrifying bacteria including Nitrospira. Further studies will be aimed at correlating these peculiar microbial conditions present in the different cave zones