From the Salar the Uyuni in Bolivia to outer spaces: Halophilic archaea and their potential to thrive on other planets

Kurzfassung

Halophilic archaea have long been prime candidates for studying potential Earth-like life on other planets. These microorganisms are not only perfectly adapted to high salt concentrations, but can also withstand significant levels of radiation, exhibit high desiccation resistance, and leave behind biomarkers such as carotenoids even after death, making them detectable by humans on other planets. On Earth, halophilic archaea are found in several well-documented locations, including the Dead Sea, Antarctica, ancient halite from the Zechstein Ocean, and Bolivia. The Salar de Uyuni in Bolivia is an ideal location for studying halophilic organisms. In addition to its high salt concentration, the high elevation (approximately 3,600 meters above sea level) plays a crucial role in this unique environment. During a field trip, in collaboration with the Center of Biotechnology from the Universidad Mayor de San Simón in Cochabamba, Bolivia, we collected hypersaline samples from four different locations: two directly in the Altiplano and two at the edges of the salt desert. The salinity ranged from 10% to saturation, and both salt crystals and liquid samples were collected. Additionally, we recorded environmental parameters such as temperature, UV radiation, and ionizing radiation. Upon returning to the lab, the samples were gently dissolved in a TN buffer containing 20% NaCl for cultivation. The dissolved samples were then spread onto different plates and incubated at various temperatures for up to three months. For molecular analysis, DNA was extracted and analyzed using the Illumina® MiSeq Platform with primers targeting the V3/V4 region. Preliminary results indicate a vast diversity of halophilic archaea, with representatives of the genus Halorubrum, Haloarcula as well as Natromonas. We were able to cultivate several possible novel species and they show an increased resistance in desiccation as well as radiation. Besides halophilic archaea, we were able to cultivate some yet unidentifiedcyanobacteria, possibly Dunaliella salina. Illumina Sequencing revealed a much broader diversity of halophiles and results of this analysis will be presented. The Salar de Uyuni is an environment of particular interest because its radiation levels can be up to seven times higher than those in other parts of the world. While active life on the surface of Mars is unlikely due to the high radiation levels, halophilic archaea have demonstrated the ability to survive trapped in halite for up to 250 million years. Considering this, halophilic archaea are ideal terrestrial organisms for studying the limits of life and the conditions that may support life on other planets.