Introduction

Extreme saline habitats have emerged as captivating hotspots for astrobiological exploration. Despite being commonly perceived as inhospitable, these environments host a range of extremophiles. One such extreme habitat is the Lüneburger brine, characterized by a saturated saline solution that surpasses all other European brines in terms of salinity. Historically utilized as a source of salt, this brine offers easy accessibility for sampling campaigns. The significance of extremophiles isolated from saline environments lies in their potential to provide crucial insights into the boundaries of life on Earth and, by extension, the prospect of extraterrestrial life. The study aims to characterize the Lüneburger brine in Germany. Cultivation and cultivation independents methods will be used to further investigate the extreme microbial community and to evaluate if this brine represents an astrobiological relevant habitat.

Methods

In this study, we conducted sampling of the Lüneburger brine. Analyses encompassed the metagenome, the cultivable community, and more. Selected isolates were further tested on potential resistances to astrobiological relevant stressors like radiation.

Results

Metagenomic data unveiled the presence of halophilic Archaea, showcasing thermophilic, halophilic, and acidophilic characteristics. Several representatives were identified as candidate organisms, yet to be isolated in a pure culture. Microscopic analysis indicated variations in morphology, with the isolates displaying pleomorphism. Cultivated organisms exhibited the presence of the carotenoid bacterioruberin. Future experiments will assess the resistance of these isolates to common astrobiological stressors.

Summary

The Lüneburger brine displays an extreme habitat displaying a saturated saline solution. However, our study has shown the wide diversity of especially halophilic microorganism which thrive in this habitat. The study emphasis the potential of this easily accessible habitat for current astrobiology research and shows the presence of isolates capable of diverse resistance towards high salinity, radiation and more revealing pleomorphism and pigmentation.