Seasonality Is the Main Determinant of Microbial Diversity Associated to Snow/Ice around Concordia Station on the Antarctic Polar Plateau

Biology (Basel). 2023 Aug 31;12(9):1193. doi: 10.3390/biology12091193.

Abstract

The French-Italian Concordia Research Station, situated on the Antarctic Polar Plateau at an elevation of 3233 m above sea level, offers a unique opportunity to study the presence and variation of microbes introduced by abiotic or biotic vectors and, consequently, appraise the amplitude of human impact in such a pristine environment. This research built upon a previous work, which explored microbial diversity in the surface snow surrounding the Concordia Research Station. While that study successfully characterized the bacterial assemblage, detecting fungal diversity was hampered by the low DNA content. To address this knowledge gap, in the present study, we optimized the sampling by increasing ice/snow collected to leverage the final DNA yield. The V4 variable region of the 16S rDNA and Internal Transcribed Spacer (ITS1) rDNA was used to evaluate bacterial and fungal diversity. From the sequencing, we obtained 3,352,661 and 4,433,595 reads clustered in 930 and 3182 amplicon sequence variants (ASVs) for fungi and bacteria, respectively. Amplicon sequencing revealed a predominance of Basidiomycota (49%) and Ascomycota (42%) in the fungal component; Bacteroidota (65.8%) is the main representative among the bacterial phyla. Basidiomycetes are almost exclusively represented by yeast-like fungi. Our findings provide the first comprehensive overview of both fungal and bacterial diversity in the Antarctic Polar Plateau's surface snow/ice near Concordia Station and to identify seasonality as the main driver of microbial diversity; we also detected the most sensitive microorganisms to these factors, which could serve as indicators of human impact in this pristine environment and aid in planetary protection for future exploration missions.

Keywords: Antarctic Polar Plateau; amplicon sequencing; bacteria; extraterrestrial analogue; extremophiles; fungi; life detection.

Grants and funding

This research was supported by the National Antarctic Research Program (MIcrobial Diversity within the Vicinity of the Concordia Antarctic Station _MIDAS project grant PNRA 2016_00101 to D.B. and L.S.). N.J.U. and R.M. were supported by the DLR grant FuE-Projekt “ISS LIFE” (Programm RF-FuW, TP 475). The BacFinder project was supported by a Europlanet 2020 RI grant from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 654208. C.C. is supported by the European Commission under the Marie Sklodowska-Curie Grant Agreement No. 702057 (DRYLIFE).