Intrathalline Fungal and Bacterial Diversity Is Uncovered in Antarctic Lichen Symbioses.

Although the Antarctic continent represents one of the most hostile environments on earth, microbial life has adapted to cope with these extreme conditions. Lichens are one of the most successful groups of organisms in Antarctica, where they serve as unique niches for microbial diversification. We have selected eight epilithic lichen species growing in Victoria Land (three cosmopolitan and five endemic to Antarctica) to describe with amplicon sequencing the diversity of the associated fungal and bacterial communities. The lichen mycobiota is predominantly composed of Ascomycota belonging to the classes Chaetothyriomycetes and Dothideomycetes, while a few key representative taxa were recognised as basidiomycetous yeasts. Bacteria associated with lichens were represented by Pseudomonadota, Cyanobacteria, and Bacteroidota in which psychrophilic genera were identified. The microbiota was diverse among the lichen species, and their variation was driven by the lichen species itself and their endemic or cosmopolitan distribution. There was a strong association of the microbial communities linked to the lichen itself, rather than to the specific characteristics of the collecting site. The lichen thallus, thus, plays an important role in microbial diversification and may potentially act as a selective biodiversity filter in which different fungal and bacterial communities thrive in it.