Bacterial and archaeal community structure in benthic sediments from glacial lakes at the Múlajökull Glacier, central Iceland

Glacial lakes and their sediments are highly sensitive temporal markers of environmental variability. The combination of particular geographical conditions with climate changes makes the Mulajokull lakes an appropriate model for revealing some site-specific and common relationships in psychrophilic microbial ecology. The aim of this study was to evaluate the taxonomic and functional diversity of microbial community structures in five glacial lake sediments situated at different distances from the glacier, i.e., 50 m to 1750 m from the ice margin. The Shannon diversity indices varied in the range from 1.99 to 2.94 (with the lowest in C sample) tested by EcoPlates™ and from 1.69 to 1.89 at the phylum level (with the lowest in A sample) tested by the shotgun metagenomic sequencing, respectively. An inter-sample comparison was also conducted. Overall, six bacteria phyla (Proteobacteria, Cyanobacteria, Bacteroidetes, Actinobacteria, Verrucomicrobia and Planctomycetes) and one microalgae phyla (Bacillariophyta) were detected in five lake sediments tested at abundancy that exceeded 1%. Obtained data brings new knowledge related to the cold biosphere on the local and global Earth systems.