Low bacterial diversity and nitrates in cores from deep karst boreholes

The objectives of this study were to assess the nitrate gradient within the deep biosphere in the carbonate rocks and its correlation with the associated microbiota. The investigation aimed to explore the microbial diversity and its metabolic potential on nitrogen cycling due to increasing issue of elevated nitrates in karst areas, and to provide an overview of the microbial colonization within the deep karst biosphere. The samples used in the study were obtained from cores extracted from borehole wells, reaching depths of up to 350 meters during the geological prospection conducted prior to the construction of underground railway tunnels within the karst region in Slovenia.