Understanding the microbiome diversity through a combination of remote sensing and close-range field observation techniques in the Sør Rondane Mountains, East Antarctica

The sparse ice-free regions of Antarctica are the coldest arid deserts on Earth. Yet, ice-free soils harbor substantial and diverse microbial communities that can vary significantly between the regions and the micro-climatic conditions. The factors responsible for driving the microbial diversity and community structure in inland nunataks of East Antarctica, like the Sør Rondane Mountains, are still poorly understood. Within the BELSPO MICROBIAN project, three sampling campaigns took place in a 70 km radius around the Belgian Princess Elisabeth Station during the Austral summers of 2018, 2019 and 2020, resulting in the biggest sampling effort for microbial analysis in the region. Samples ranged from different kind of barren bedrock to substrates covered by biofilms and well-developed biological soil crusts consisting of lichens, mosses and cyanobacterial/microalgal mats. In this study, long-term microenvironmental monitoring data show that temperature and soil humidity regimes vary with the elevation, slope, aspect, wind exposure and daily irradiance regimes of the surveyed nunataks. Bacterial and eukaryotic diversity were assessed by amplicon sequencing targeting 16S and 18S regions of the rRNA genes with the Illumina MiSeq platform (2x300 bp). Preliminary multivariate analysis indicate that habitat characteristics derived from remote sensing and data loggers give important insights about the distribution of bacteria, cyanobacteria and eukaryotes in these unique environments. Further analyses are ongoing on chemical characterization of the soils and on potential biotic interactions to better understand the terrestrial microbial ecology of Antarctic ice-free regions.