Linking the composition of cryoconite prokaryotic communities in the Arctic, Antarctic, and Central Caucasus with their chemical characteristics.

Cryoconites are the deposits on the surface of glaciers that create specific ecological niches for the development of microorganism communities. The sediment material can vary in origin, structure, and nutrient content, creating local variations in the growth conditions. An additional factor of variability is the location of the glaciers, as they are found in different climatic zones in the high mountain regions and closer to the poles. Here, using the analysis of amplicon sequencing of the 16S rRNA gene, we studied the taxonomic composition of the prokaryotic communities from glaciers from remote regions, including the Arctic (Mushketova on the Severnaya Zemlya, IGAN in Polar Ural), Antarctic (Pimpirev on the Livingstone Island) and Central Caucasus (Skhelda and Garabashi) and connected it with the variation of the physicochemical characteristics of the substrate: pH, carbon, nitrogen, macro- and microelements. The cryoconite microbiomes were comprised of specific for this environment phyla (mostly Pseudomonadota, Cyanobacteria, Bacteroidota, Acidobacteriota, and Actinobacteriota), but each glacier had a unique taxonomic imprint. The core microbiome between regions was composed of only a few ASVs, among which the most likely globally distributed ones attributed to Polaromonas sp., Rhodoferax sp., Cryobacterium sp., and Hymenobacter frigidus. The WGSNA defined clusters of co-occurring ASVs between microbiomes, that significantly change their abundance corresponding with the variation of chemical parameters of cryoconites, but do not fully coincide with their regional separation. Thus, our work demonstrates that the chemical characteristics of the sediment material can explain the variation in the cryoconite prokaryotic community which is not always linked to geographic isolation.