The microbial diversity of the Su Bentu cave, Italy and the influence of human exploration

The microbial diversity in the Su Bentu Cave (Sardinia, Italy) was investigated by means of Illumina MiSeq analysis. The hypogean environment is of great interest for astrobiological research as cave conditions may resemble those in extra-terrestrial re-gions. Furthermore, they hold high potential to identify novel, extremely adapted organisms to severely oligo-trophic habitats. However, the influence of human is not neglectable and in-depth investigations are needed to determine the impact of exploration on an otherwise mostly pristine ecosystem. The cave in-vestigated in this study develops for several kilometers into the mountain, two hundred meters below the topographic surface and is characterized by a strong air circulation. Its structure is composed of huge pas-sages carved in limestone where an ephemeral under-ground stream creates some lakes, close to which seven samples of visible calcite rafts, manganese de-posits and moonmilk (a hydrated calcium carbonate speleothem), were sampled during an expedition in 2014. Other samples were retrieved from a frequently used campsite and from some dry cave passages leading deeper into the cave.