Fungal diversity in seasonal snow of Martel Inlet, King George Island, South Shetland Islands, assessed using DNA metabarcoding

Antarctic snow represents a microhabitat directly linked with atmospheric precipitation, and through it receives dust, sea spray, organic materials and microbial propagules. Among the microorganisms that inhabit Antarctic snow, fungi are not well known. In the current study, we assessed the uncultured fungal diversity in seasonal snow samples obtained from King George Island (South Shetland Islands, maritime Antarctica) using DNA metabarcoding by high-throughput sequencing. We detected 65 fungal amplicon sequence variants (ASVs) dominated by the phyla Ascomycota, Basidiomycota and Mortierellomycota. In addition, ASVs of the basal cryptic and uncommon phyla Chytridiomycota and Rozellomycota were detected. Fungal species Microbotryomycetes sp. 1, Chytridiomycota sp. and Leucosporidiales sp. 1 were the most dominant ASVs. Twenty-nine fungal ASVs could only be identified at higher taxonomic levels and may represent previously unknown fungi, taxa unreported in the available databases and/or new records for Antarctica. The community detected in the seasonal snow displayed moderate indices of diversity, richness and dominance. The fungal assemblages included cosmopolitan, psychrophilic, saprophytic, mutualistic, and plant and animal pathogenic taxa. DNA metabarcoding revealed higher fungal sequence diversity accumulated during the previous winter when compared with previous culturing studies, including taxa of the basal cryptic uncommon phyla. Snow is among the most widespread and threatened ecosystems in maritime Antarctica due to the effects of climate changes over the last few decades; therefore, the high uncultured fungal diversity detected in this study reinforces the need for further taxonomic, ecological, life history strategy and genetic studies across Antarctica to understand fungal biology and potential for use in biotechnological applications