Fungal and bacterial diversity of Svalbard subglacial ice

Abstract

The composition of fungal and bacterial communities in three polythermal glaciers and associated aquatic environments in Kongsfjorden, Svalbard was analysed using a combination of cultivation and amplicon sequencing. 109 fungal strains belonging to 30 mostly basidiomycetous species were isolated from glacial samples with counts up to 10³ CFU/100 ml. Glaciozyma-related taxon and Phenoliferia psychrophenolica were the dominant species. Unexpectedly, amplicon sequencing uncovered sequences of Chytridiomycota in all samples and Rozellomycota in sea water, lake water, and tap water. Sequences of Malassezia restricta and of the extremely halotolerant Hortaea werneckii were also found in subglacial habitats for the first time. Overall, the fungal communities within a glacier and among glaciers were diverse and spatially heterogenous. Contrary to this, there was a large overlap between the bacterial communities of different glaciers, with Flavobacterium sp. being the most frequently isolated. In amplicon sequencing Actinobacteria and Proteobacteria sequences were the most abundant.

Figure 1

Location of the sampling site in the Kongsfjorden area, with insert showing the relative position of the sampling region within Svalbard. Map is acquired as an image from TopoSvalbard credit NPI/USGS Landsat, with courtesy of the Norwegian Polar Institute. Norwegian Polar Institute. Svalbard map [map]. Scale [1:6000000]. “TopoSvalbard” <https://toposvalbard.npolar.no> (Accessed January 21, 2019); Map data and orthophoto based on aerial imagery of 2010 and 13828 [map]. Scale [1:200000]. “TopoSvalbard”<https://toposvalbard.npolar.no>(Accessed January 21, 2019).

Figure 2

Percent of fungal operational taxonomic units (OTUs) aligned and assigned to known fungal classes based on PCR amplifications of ITS2 gene sequences for all the sample types.

Figure 3

Heatmap showing the total abundance of each class in each sample of subglacial ice (S-ice), clear ice (C-ice), sea water (Sea), glacial meltwater (G-wtr), lake water (L-wtr), and tap water (Tap) collected from Ny-Ålesund, Svalbard. The branch length of the cluster dendogram show the similarity level. Clustering among samples was based on hierarchical cluster analysis (hclust).

Figure 4

Principal coordinate analysis (PCoA) ordination patterns based on weighted uniFrac distance of fungi (A) and bacteria (B).

Figure 5

Percent of bacterial operational taxonomic units (OTUs) aligned and assigned to known bacterial phyla based on PCR amplifications of 16S gene sequences for all the sample types.

Figure 6

Principal Component Analysis (PCA) based on presence/absence data of fungal species in the studied environments. Abbreviations: Midtre Lovénbreen (ML); Midtre Lovénbreen glacial meltwater (GW_ML); Vestre Brøggerbreen (VB); Pedersenbreen (PB).