Mortierellaceae diversity at earliest soil developmental stages of four calcareous glacier forefields—An isolation-based approach

Mortierellaceae are an essential part of the core soil microbiome, occurring in all terrestrial habitats, including nutrient-poor terrains like glacier forefields. Recently deglaciated areas are of interest from an ecological perspective, because they enable us to study the development of early-stage pioneer microbial communities. We aimed to investigate whether glacier forefields harbor abundant members of Mortierellaceae and to determine their distribution in four glacier forefields across the Alps (Switzerland: Griessen, Tsanfleuron; Italy: Marmolada; Austria: Dachstein). This study was based on an isolation-driven approach by direct plating. A total of twenty sediments from recently deglaciated areas (less than twenty-five years ice-free) with minimal to no plant development and low soil organic material were analyzed. Fungal pure culture isolates were identified via rDNA-ITS sequencing and phylogenetic analysis. In total, sixteen species from five different genera were detected. The genus Mortierella was the most abundant and occurred in all four glacier forefields. Many of the isolated species are globally distributed. Additionally, two so far undescribed lineages could be isolated, which are prospects for novel taxa. The results emphasize a high undiscovered diversity of Mortierellaceae within the investigated glacier forefields and suggest that these fungi have an ecological impact on soil development in alpine ecosystems.