Biogeography of soil bacterial populations in the Jutulsessen and Ahlmannryggen of Western Dronning Maud Land, Antarctica

Abstract

Soils of continental Antarctic nunataks represent unusual ecosystems with concomitant unique bacterial community profiles which have not been assessed for the vast majority of Antarctic nunataks. This study focussed on the previously uncharacterised inland nunataks of the Jutulsessen and Ahlmannryggen ranges in Dronning Maud Land. As with many oligotrophic soils in Antarctica, bacteria from the phyla Acidobacteria, Actinobacteria and Proteobacteria were prevalent. High relative abundances of Bacteroidetes and Chloroflexi were also observed in these soils. Potential phototrophic capabilities of these bacterial populations were indicated by the presence of genes involved in the Calvin–Benson reductive pentose phosphate cycle as well as that of aerobic phototrophic bacteriochlorophyll. Clear spatial patterns of bacterial biodiversity between nunataks in this study were observed, particularly between the Jutulsessen and Ahlmannryggen nunataks which are geographically separated by the Jutulstraumen glacier. Not unexpectedly, the bacterial community profiles found in these nunataks were distinct from those found in alternate biogeographic regions (e.g. Dry Valleys, Peninsula and Larsemann Hills). Despite belonging to the same bioregion (i.e. Dronning Maud Land), however, the clear differentiation of bacterial communities between the Jutulsessen/Ahlmannryggen and that of Sor Rondane suggests that, based on bacterial phylogeography, the Dronning Maud Land bioregion can be divided into sub-bioregions.