Revealing the diversity of bacteria and fungi in the active layer of permafrost at Spitsbergen island (Arctic) - Combining classical microbiology and metabarcoding for ecological and bioprospecting exploration.

Arctic soils are constantly subjected to extreme environmental conditions such as low humidity, strong winds, high salinity, freeze-thaw cycles, UV exposition, and low nutrient availability, therefore, they have developed unique microbial ecosystems. These environments provide excellent opportunities to study microbial ecology and evolution within pristine (i.e. with limited anthropogenic influence) regions since the High Arctic is still considered one of the wildest and least explored environments on the planet. This environment is also of interest for the screening and recovery of unique microbial strains suitable for various biotechnological applications. In this study, a combination of culture-depended and culture-independent approaches was used to determine the cultivation bias in studies of the diversity of cold-active microorganisms. Cultivation bias is a reduction in recovered diversity, introduced when applying a classical culturing technique. Six different soil types, collected in the vicinity of the Polish Polar Station Hornsund (Spitsbergen, Norway), were tested. It was revealed that the used media allowed recovery of only 6.37 % of bacterial and 20 % of fungal genera when compared with a culture-independent approach. Moreover, it was shown that a combination of R2A and Marine Broth media recovered as much as 93.6 % of all cultivable bacterial genera detected in this study. Based on these results, a novel protocol for genome-guided bioprospecting, combining a culture-dependent approach, metabarcoding, next-generation sequencing, and genomic data reuse was developed. With this methodology, 14 psychrotolerant, multi-metal-resistant strains, including the highly promising Rhodococcus spp., were obtained. These strains, besides increased metal tolerance, have a petroleum hydrocarbon utilization capacity, and thus may be good candidates for future bioremediation technologies, also suited to permanently cold regions.

Psychronectria hyperantarctica, gen. nov., comb. nov., epitypification and phylogenetic position of an Antarctic bryophilous ascomycete.

The holotype of Thyronectria hyperantarctica was re-examined, redescribed, and compared with new collections of an Antarctic bryophilous ascomycete from a similar area. Because the condition of type material was insufficient for molecular studies, the authors designated an epitype from newly collected material with a high degree of morphological similarity to the holotype and paratype material. Phylogenetic analysis of the epitype revealed that its closest phylogenetic affinity was with the family Tilachlidiaceae and it formed a monophyletic group in this lineage within other collections of the species. Therefore, the new monotypic genus Psychronectria is described to accommodate Thyronectria hyperantarctica. The fungus is superficially similar to Thyronectria species in Nectriaceae, but the ascospores differ in color, size, and type of septation.