Abstract:
INTRODUCTION : The Antarctic McMurdo Dry Valleys are geologically diverse,
encompassing a wide variety of soil habitats. These environments are largely
dominated by microorganisms, which drive the ecosystem services of the region.
While altitude is a well-established driver of eukaryotic biodiversity in these
Antarctic ice-free areas (and many non-Antarctic environments), little is known
of the relationship between altitude and microbial community structure and
functionality in continental Antarctica.
METHODS : We analysed prokaryotic and lower eukaryotic diversity from soil
samples across a 684 m altitudinal transect in the lower Taylor Valley, Antarctica
and performed a phylogenic characterization of soil microbial communities using
short-read sequencing of the 16S rRNA and ITS marker gene amplicons.
RESULTS AND DISCUSSION : Phylogenetic analysis showed clear altitudinal trends in
soil microbial composition and structure. Cyanobacteria were more prevalent
in higher altitude samples, while the highly stress resistant Chloroflexota and
Deinococcota were more prevalent in lower altitude samples. We also detected
a shift from Basidiomycota to Chytridiomycota with increasing altitude. Several
genera associated with trace gas chemotrophy, including Rubrobacter and
Ornithinicoccus, were widely distributed across the entire transect, suggesting
that trace-gas chemotrophy may be an important trophic strategy for microbial
survival in oligotrophic environments. The ratio of trace-gas chemotrophs
to photoautotrophs was significantly higher in lower altitude samples. Cooccurrence
network analysis of prokaryotic communities showed some significant
differences in connectivity within the communities from different altitudinal
zones, with cyanobacterial and trace-gas chemotrophy-associated taxa being identified as potential keystone taxa for soil communities at higher altitudes. By
contrast, the prokaryotic network at low altitudes was dominated by heterotrophic
keystone taxa, thus suggesting a clear trophic distinction between soil prokaryotic
communities at different altitudes. Based on these results, we conclude that altitude
is an important driver of microbial ecology in Antarctic ice-free soil habitats.
Description:
DATA AVAILABILITY STATEMENT : The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found at: https://www.ebi.ac.uk/ena, PRJEB55870.