Community structure and distribution of benthic cyanobacteria in Antarctic lacustrine microbial mats

The terrestrial Antarctic Realm has recently been divided into 16 Antarctic Conservation Biogeographic Regions (ACBRs) based on environmental properties and the distribution of biota. Despite their prominent role in the primary production and nutrient cycling in Antarctic lakes, cyanobacteria were only poorly represented in the biological dataset used to delineate these ACBRs. Here, we provide a first high-throughput sequencing insight into the spatial distribution of benthic cyanobacterial communities in Antarctic lakes located in four distinct, geographically distant ACBRs and covering a range of limnological conditions. Cyanobacterial community structure differed between saline and freshwater lakes. No clear bioregionalization was observed, as clusters of community similarity encompassed lakes from distinct ACBRs. Most phylotypes (77.0%) were related to cyanobacterial lineages (defined at >= 99.0% 16S rRNA gene sequence similarity) restricted to the cold biosphere, including lineages potentially endemic to Antarctica (55.4%). The latter were generally rare and restricted to a small number of lakes, while more ubiquitous phylotypes were generally abundant and present in different ACBRs. These results point to a widespread distribution of some cosmopolitan cyanobacterial phylotypes across the different Antarctic ice-free regions, but also suggest the existence of dispersal barriers both within and between Antarctica and the other continents.