Microbiology of a <scp>NaCl</scp> stalactite ‘salticle’ in Triassic halite

Large regions of Earth's surface are underlain by salt deposits that evaporated from ancient oceans and populated extreme halophilic microbes. Some these halophiles may have been preserved over geological timescales within hypersaline fluid inclusions, but ingresses water and/or anthropogenic activities can lead to the formation alternative habitats, including NaCl stalactites or other speleothems. While microbiology evaporites has well studied, ecology recently formed structures is less-well understood. Here, a stalactite (‘salticle’) in Triassic halite mine characterized. The specific aims were determine presence microbial structure salticle compared with nearby brine-pool surficial soil, characterize ecophysiological capabilities this unique ecosystem. contained their microbiome was composed Euryarchaetota, Proteobacteria, Actinobacteria, Haloarchaea greater abundance than soil microbiomes. metagenome exhibited genes involved osmoregulation, anaerobic respiration, UV resistance, oxidative stress, stress-protein synthesis relative microbiome. We discuss potential astrobiological implications salticles as enclosed salt-saturated habitats protected ionizing radiation stable activity.