Isolation and Characterization of Halophilic Archaea Extracted From The Extreme Salty Habitat of Lüneburg Brine and Their Relevance in Space Biology

Abstract

The Lüneburg salt formation in Lower Saxony, Germany, offers unique insights into the region’s hydrochemistry and geological history. This formation is linked to the ancient Zechstein Sea, which left behind massive salt deposits as it evaporated. These deposits create a hypersaline environment beneath the city of Lüneburg, making it an ideal site for studying extremophiles, such as halophilic archaea, which thrive in extreme salinity. In this study, halophilic archaeal communities from the Lüneburger Brine were analysed, including the whole brine population and two specific isolates: strain AS12, related to the genus Halorubrum, and strain NS06, belonging to the genus Haloarcula. Characterisation was performed using morphological, biochemical, and molecular techniques. The morphological analysis involved microscopy to determine cell shape, while the biochemical tests evaluated metabolic capabilities, such as the utilisation of various carbon and nitrogen sources and tolerance to different salt concentrations. Molecular techniques, including 16S rRNA gene sequencing, were used to establish the phylogenetic relationships of the isolates within the archaeal domain. To evaluate their potential for astrobiological applications, strain NS06 was exposed to stress tests that simulated extraterrestrial conditions, including desiccation and ionising radiation. These experiments demonstrated the ability of Lüneburg archaeal communities to utilise diverse nutrient sources and withstand varying salt concentrations, as well as highlighted NS06’s high resistance to desiccation. The findings from this project deepen our understanding of microbial survival in extreme environments and emphasise their importance in exploring the habitability of extraterrestrial settings, advancing the search for life beyond Earth.