SRA

Hard rock aquifers are heterogeneous and dynamic environments hosting a broad diversity of microorganisms which play a critical role in subsurface biogeochemical cycling and pollutant degradation. Metagenomics is a potent approach to obtain a thorough picture of the gene and taxon composition of microbial communities. Yet, the need to cultivate microorganisms in order to test hypotheses related to their metabolism, their ecological niches and their roles in environmental processes remains critical. The site study is located near the city of Guidel (Brittany, Western France) and is part of the French network of hydrogeological observatories (H+ hplus.ore.fr/en) and the OZCAR Critical Zone observatories. Previous studies led in Guidel have shown that the aquifer system is separated in two entities: (i) the weathered zone, which is actively recharged, presents recent (apparent age ranging from 10 to 20 years), oxygenated groundwater, (ii) the deeper fractured area characterized by ancient (apparent age of about 100 years), oxygen-poor, iron-rich groundwater.