Microbial diversity in extreme, anoxic MASE sites

Fueled by the general interest of detecting life beyond Earth's biosphere, the chemical and physical limits of life and thus borders of habitability remain a burning question. Studying extreme terrestrial environments on Earth and their endogenous life can help to decipher basic information on evolution and adaptation capabilities of microorganisms - a prerequisite for life detection on other planetary bodies. Earth's ecosystem has undergone tremendous changes, including the formation of oxygen, a feature that probably distinguishes our planet from potential habitable extraterrestrial systems. Motivated by the identified significant lack of information on microbial communities from Mars-analogue, anoxic settings, and the desire to understand the characteristics and limits of anaerobic life, we carried out the first systematic microbiological study of a number of terrestrial anoxic environments with space-relevant extremes (high salinity, acidity, presence of sulfate, poor nutrient availability, low temperature). We investigated the inhabiting microbial community using a wide-scale cultivation approach and deep amplicon sequencing of the archaeal and bacterial 16S rRNA genes of the intact portion of the microbial community. 1034 enrichment attempts delivered more than 20 novel, anaerobic model organisms with strong astrobiological relevance, whereas NGS uncovered a highly adapted bacteriome and archaeome, thriving under harsh conditions. Notably, an intact, cosmopolitan group of microorganisms was detected in all samples from Mars-analogue environments. The outcome of this project will certainly be a highly valuable catalogue for microbial community analysis in anoxic environments, with a strong impact for the search for life in the universe.