Fungal diversity present in ornithogenic soils of extreme equatorial Atlantic São Pedro and São Paulo archipelago using DNA metabarcoding.

We evaluated the fungal diversity present in ornithogenically-influenced soils of the polyextreme Brazilian Archipelago of São Pedro and São Paulo, using a DNA metabarcoding approach. We detected 1,596,919 fungal DNA reads grouped into 232 amplicon sequence variants (ASVs). The phylum Ascomycota was the dominant phylum, followed by Basidiomycota, Blastocladiomycota, Mortierellomycota, Mucoromycota, Aphelidiomycota, Rozellomycota, Chytridiomycota and Zoopagomycota, in rank abundance order. Cladosporium sp., Hortaea werneckii, Penicillium sp., Aspergillus sp. and Fungal sp. were the dominant assigned taxa. The fungal assemblages displayed high diversity indices, although differing between the sites sampled. Fifty-four fungal ASVs could only be assigned to higher taxonomic levels, primarily those of the cryptic and poorly known phyla Aphelidiomycota, Blastocladiomycota, Chytridiomycota and Rozellomycota. These may represent taxa not currently included in the available databases or new taxa and/or new records for the São Pedro and São Paulo archipelago. Only Cladosporium sp., Hortaea werneckii, Blastobotrys serpentis and Penicillium sp. were detected in all sites. Even though the São Pedro and São Paulo archipelago experiences extreme environmental conditions, the use of metabarcoding revealed a diverse and complex fungal community potentially present in the samples examined. The assigned fungal communities were dominated by genera which commonly display high adaptive plasticity when facing challenging and extreme conditions. The melanized yeast H. werneckii, known for its high resistance to polyextreme conditions, illustrates that this archipelago represents a potential source of extremophilic fungi. The dominant assigned fungi include taxa with different ecological roles, with some also recognized as potentially important animal pathogens.