Speleomycological and chemical assessment of sediments in Demänovská Slobody Cave (Slovakia)

Our study unveils the complex interplay between fungal diversity and geochemical environments within the Demänovská Slobody Cave, marking the first comprehensive speleomycological and chemical investigation of its kind. Through meticulous analysis using both microscopic techniques and ITS region gene barcoding, we recorded 17 fungal species, including four previously unrecorded in subterranean settings (Cladosporium ramotenellum, Porostereum spadiceum, Rhexocercosporidium carotae, and Trichocladium nigrospermum), with Porostereum spadiceum as the most prevalent. These findings illuminate the crucial role of fungi in subterranean biogeochemical cycles, demonstrating how nutrient levels and pH significantly influence fungal populations. Namely, the levels of mineral nutrients (N, P, K, Mg, Ca) and organic matter in sediments within the cave were lower than in soil those outside it. Conversely, the pH values of the tested samples inside the cave were higher compared to those outside. Positive correlations were observed between the average number of fungi and the content of N, P, K, CO, and organic matter (p < 0.05). Conversely, the concentration of fungi decreased with increasing levels of Mg, Ca, and pH (p < 0.05). This research not only expands our understanding of cave ecosystems but also sets a new precedent for exploring the ecological impact of fungi in extreme environments.