Mycobiota in Peatlands of the Discontinuous Permafrost Zone (Murmansk Oblast)

Peatlands are an extremely challenging environment for microbial life. Most studies of fungi in such biotopes have focused on temperate-zone bogs, while northern bogs, including those in permafrost regions, remain poorly investigated. The aim of this work was to study the species diversity of culturable filamentous fungi from the soils of a bog located in the sporadic permafrost zone of the Maivaltayok River delta (Kola Peninsula, Murmansk oblast). We used peat samples from four soil profiles, two of which were sampled down to the permafrost layer. The average fungal abundance (CFU) ranged from 102 to 105 per gram of dry substrate, with a high content of fungal propagules in the upper parts of the profile. The relatively low species diversity was represented mainly by Ascomycota, with a predominance of Eurotiomycetes. Dominant genera included Penicillium spp. (P. spinulosum and P. glabrum, found throughout the peat column and at all sampling times) and Talaromyces spp. The characteristic diversity of Leotiomycetes, known as decomposers of Sphagnum mosses and other vegetation in oligotrophic bog systems, was observed (including Oidiodendron spp. and various Helotiales species). Sordariomycetes were represented by entomopathogenic species (with a high occurrence of Tolypocladium inflatum) and Trichoderma spp. Among Mucoromycota, Umbelopsis vinacea was present in all profiles. Basidiomycota were not detected. Many of the species are known as psychrotolerant organisms capable of growth at low temperatures. The affiliation of the identified species to different ecological–trophic groups characteristic of this biotope is discussed.