No abstract

The diversity of bacteria present in surface snow around four Russian stations in Eastern Antarctica was studied by high throughput sequencing of amplified 16S rRNA gene fragments and shotgun metagenomic sequencing. Considerable class- and genus-level variation between the samples was revealed indicating a presence of inter-site diversity of bacteria in Antarctic snow. Flavobacterium was a major genus in one sampling site and was also detected in other sites. The diversity of flavobacterial type II-C CRISPR spacers in the samples was investigated by metagenome sequencing. Thousands of unique spacers were revealed with less than 35% overlap between the sampling sites, indicating an enormous natural variety of flavobacterial CRISPR spacers and, by extension, high level of adaptive activity of the corresponding CRISPR-Cas system. None of the spacers matched known spacers of flavobacterial isolates from the Northern hemisphere. Moreover, the percentage of spacers with matches with Antarctic metagenomic sequences obtained in this work was significantly higher than with sequences from much larger publically available environmental metagenomic database. The results indicate that despite the overall very high level of diversity, Antarctic Flavobacteria comprise a separate pool that experiences pressures from mobile genetic elements different from those present in other parts of the world. The results also establish analysis of metagenomic CRISPR spacer content as a powerful tool to study bacterial populations diversity.

Abstract-The content and individual component compositions of polycyclic aromatic hydrocarbons in polar soils of the Russian Arctic sector have been studied. The contamination of soils near research stations is identified from the expansion of the range of individual polycyclic aromatic hydrocarbons, the abrupt increase in the content of heavy fractions, and the accumulation of benzo[a]pyrene. Along with heavy hydro carbons, light hydrocarbons (which are not only natural compounds, but also components of organic pollut ants) are also accumulated in the contaminated soils. Heavy polycyclic aromatic hydrocarbons are usually of technogenic origin and can serve as markers of anthropogenic impact in such areas as Cape Sterligov, Cape Chelyuskin, and the Izvestii TsIK Islands. The content of benzo [a]pyrene, the most hazardous organic toxi cant, appreciably increases in soils around the stations, especially compared to the control; however, the level of MPC is exceeded only for the soils of Cape Chelyuskin.

Biodiversity and number of airborne fungi isolated from indoor and outdoor air of different location in the areas of arctic settlement Tiksi (Russian Arctic) are described. Different locations (coastal areas, landscape, streets of Tiksi, abandoned empty houses, flats, public buildings) were observed. Aeromycota characterized by a significant biodiversity (50 species), but only several species were abundant. Airborne fungal spores concentration (CFU) in Tiksi locations was found low. The maximum spore concentrations were observed in air of the abandoned empty houses (inhabited in the past). Many species common for soil were observed at the samples taken at streets and abandoned buildings. Most of them are also known as inhabitants of building materials. Microfungi CFU at settlement territory was twice as high as natural territory. Phospholipase, albuminase and hemolytic activities of microfungi isolates as well as their relation to temperature were studied. Most of the tested isolates demonstrated high levels of all the tested activities. It was concluded that there is a risk of ''mold'' allergy diseases for the people especially with weakening of immunity at arctic settlement Tiksi. Main sources of the air contamination in arctic settlements and houses could be many anthropogenic substrates which were colonized by soil fungi.

The composition and the structure of microbial communities in areas of Arctic settlements were studied. The main attention has been given to microscopic fungi. As result of observation of 5 Arctic regions 117 species of microscopic fungi are revealed in soils and anthropogenic substrates. The identification was carried out with the use ofmycological and molecular genetic methods. Most ofspecies belong to the Ascomycotina. Genus Penicillium is characterized by the most species diversity (24 species). Most offungi are destructors of various materials and potential human pathogens. Dominant species are revealed. The distribution of microorganisms in the living and working areas of polar stations, as well as the adjacent areas are described. Black-colored fungi adapted to unfavorable environment are often the dominated group of microorganisms on soils and anthropogenic substrates. The shaping of soil microbiota was shown to be related to the anthropogenic impact. Considerable similarity of microbial communities composition in the soil and man-made substrates is fixed. As result of mycological analysis of contaminated soils 76 species of microscopic fungi were observed, but 41 species of them (53.9%) were identified in the areas of Arctic polar stations on the man-made materials. These species include the representatives of the genera Alternaria, Aspergillus, Aureobasidium, Chaetomium, Cladosporium, Exophiala, Geomyces, Humicola, Penicillium, Mucor, Phoma, Rhodotorula, Trichoderma and Ulocladium. The obtained data show a significant similarity in species composition of contaminated soils and anthropogenic substrates. Human activity contributes to the distribution of cosmopolitan species, including opportunistic fungi, in the Arctic region. The high numbers of organotrophic bacteria were revealed in soil samples. Some species of microorganisms produce the organic acids in an external environment that promotes the erosion of materials.