Fungal Dark Matter refers to uncultivated or undescribed fungi with <5% of species successfully recovered in the laboratory. The harsh conditions prevalent in Antarctica force microbes to adapt and develop a high level of resilience to survive, thus we expect a high proportion of novel species to inhabit cold region soils. Robinson Ridge in Eastern Antarctica is an underexplored arid desert ecosystem, and in this study, we used culture-dependent and culture-independent methods to uncover the diversity and environmental drivers of the endemic soil fungal communities.
Amplicon sequencing from 93 subsoil samples along a 300-m spatially explicit transect in Robinson Ridge was analyzed in combination with 65 measured environmental parameters. Soil from the sites 0-m point was used to culture fungi, following enrichment under oligotrophic conditions supplemented with hydrogen gas.
A total of ~1500 zOTUs were identified across the site, predominately rock-inhabiting and lichen-forming fungi. Moisture, phosphate, ammonia, and terrain roughness were the most significant environmental variables influencing fungal community structures, with communities at the top of the slope, where soils are dry and dominated by lichenised fungi. Over 133 isolates were identified, 34 of which were unclassified at the order level, including one of the ‘world’s most wanted fungi.’ Dothideomycetes was the most common class in both soil and cultures, thus we selected novel species within this class for physiological and genomic characterization. Isolates are resilient, capable of growth at 0–5° C, with genomes revealing a high potential for novel biosynthetic gene clusters.
Our research uncovers the comprehensive Antarctic fungal diversity and introduces several novel taxa, significantly expanding our understanding of the fungal tree of life. The ongoing genomics and transcriptomics on these novel isolates promise to provide further profound insights into the biology of these Antarctic fungi.