Dorota Górniak

This study is the first to characterize the metabolic strategies of endemic and cosmopolitan bacterial species in Antarctic microbial mats. Of the 43 isolates obtained, 21 strains were identified as belonging to 12 endemic (EN) bacterial species, while 22 strains represented 16 cosmopolitan (CO) species. Metabolic profiles for these strains were determined using the Biolog Gen III microarray metabolic fingerprinting test. The results suggest a possible relationship between patterns of metabolic activity, environmental tolerance, and the biogeographic range of the species. CO strains showed statistically significantly higher metabolic activity, utilizing approximately half of the substrates, whereas EN strains utilized one-third. Statistically significant differences were observed in the utilization of sugar alcohols, amino sugars, phosphosugars, amino acids, and sugar acids. Among CO species, strains with exceptionally broad metabolic potential and high resistance to environmental factors were identified. The results confirmed the hypothesis that the metabolic strategies of bacteria in microbial mats may be determined by the original biogeographic range of the species. As indicated by this study, the presence of cosmopolitan species in polar environments alter the structure of native microbial communities. Their migration to isolated environments may contributes to the biotic homogenization of microbiomes globally, potentially leading to the gradual displacement of endemic species. Consequently, this phenomenon may influence key ecological processes in polar ecosystems, including matter cycling and the functioning of microbial communities. The current study contributes to the discussion on contemporary microbial biogeography, indicating that the geographic ranges of species may be related to metabolic strategies and environmental adaptations.

This is the first study to demonstrate a relationship between antagonistic interactions with antibiotic resistance within flavobacterial strains, a component of polar-region microbial mats. These strains were derived from ephemeral freshwater reservoirs, i.e. ponds and streams of the periglacial zone of Ecology Glacier (King George Island, maritime Antarctica). The study demonstrated the strains’ surprisingly high phylogenetic diversity, with 20 species among 50 isolates. Flavobacteria were characterised by different patterns of antagonism and sensitivity to antimicrobials. 29 strains produced substances inhibiting the growth of other isolates, with 21 strains being sensitive to such compounds; 34 strains were multidrug-resistant (MDR). The antibiotic resistance index (ARI) demonstrated a significantly higher proportion of MDR strains and ARI ≥ 0.2 in stream mats (87%) as compared to the strains derived from pond mats (55%). A strong correlation was observed between the strains’ antagonistic potential and antibiotic resistance. An important role in these phenomena is accomplished by the “super bacteria” strains that effectively accumulate numerous traits associated with antagonistic potential and can be involved in the potential transfer of these traits. The results of the study demonstrate that there are individual patterns of antagonistic interactions and antibiotic resistance among the biotic components of mats.

This study was carried out on periphytic cyanobacteria and algae assemblages of microbial mats in streams and small water bodies during the Antarctic summer of 2019 in the vicinity of Ecology Glacier (King George Island, Antarctica). The significantly diversified assemblages between the microbial mats of small water bodies and streams were observed. The higher biomass and proportion of periphytic cyanobacteria with Planktothix agardhii as dominant species were found in the streams at lower mean water temperature and higher nutrient content while diatoms generally dominated in the small water bodies (primarily Fragilaria capucina). Chlorophyta also reached a significant proportion in the total biomass of periphyton with dominant species of Prasiola crispa and Keratococcus mucicola. The growth of periphytic cyanobacteria and algae was determined mainly by type of substrate, water temperature and nutrient concentrations. The results also suggest the phenomenon of nutrient uptake by these assemblages from the waters, confirmed by the negative correlations between some species and nutrients (TN, TP, N-NH₄, P-PO₄). A large share of commonly occurring periphytic species and limitation of typically polar ones, suggest progressive changes in the eutrophication of Antarctic waters caused by the global climate change and increased pollution in the environment. Therefore, these areas should be subject to a special legal protection, preceded by detailed research of these ecosystems.

The aim of the study was to determine the Actinobacteria structure in cultivated (C) versus non-cultivated (NC) soils divided into three groups (autogenic, hydrogenic, lithogenic) with consideration its formation process in order to assess the Actinobacteria sensitivity to agricultural soil use and soil genesis and to identify factors affecting their abundance. Sixteen C soil samples and sixteen NC samples serving as controls were taken for the study. Next generation sequencing (NGS) of the 16S rRNA metagenomic amplicons (Ion Torrent™ technology) and Denaturing Gradient Gel Electrophoresis (DGGE) were applied for precise determination of biodiversity. Generally, greater abundance of Actinobacteria in the NC soils relative to the C soils was found. Moreover, it was indicated that the actinobacterial diversity depended on both the soil genesis and the land use; however, this effect directly depended on the particular family and genera. Two factors: redox potential (Eh) and total carbon (TC) seemed to had a significant effect on the diversity of Actinobacteria. More precisely, Actinobacteria from the NC soils displayed a greater affinity for each other and were clearly influenced by Eh, whilst those from the C soils were mostly influenced by TC.

The Arctic and Antarctic have been of great interest to the international community for a number of years. The still unresolved problem regarding polar regions is the still partially regulated legal issues concerning the management of these areas. Both the Arctic and Antarctica are areas of potentially great scientific, economic, political and military importance. The political and legal status of polar areas is not uniform. Currently, there is no legal international document that would regulate issues related to the management of the Arctic region. The political and legal status of Antarctica was determined in 1959 in Washington. The Antarctic treaty regulates in detail the activities in this region. Territorial claims are a particularly important problem. A number of countries prove their territorial rights to both the Arctic and Antarctic. The Arctic division is discussed within five countries, without the participation of the international community, while the Antarctic Treaty arrangements have put these issues on ice until 2049. International cooperation in the field of research of polar regions has a long history and is confirmed by bilateral and international agreements. Conducted research in the Arctic and Antarctic relate to various scientific problems. Investigations of processes taking place on Earth on a global scale are of particular importance, both in historical and prognostic perspective. The history of Polish polar research is rich, multi-faceted and dates back to the second half of the nineteenth century. Contemporary Polish polar research focuses on a number of problems: glaciology and periglacial phenomena, climatology, geomorphology, hydrology, and geo-ecosystems dynamics. Polish scientific activity, in these regions, significantly develops our positive relations with the international community.

Polaromonas is one of the most abundant genera found on glacier surfaces, yet its ecology remains poorly described. Investigations made to date point towards a uniform distribution of Polaromonas phylotypes across the globe. We compared 43 Polaromonas isolates obtained from surfaces of Arctic and Antarctic glaciers to address this issue. 16S rRNA gene sequences, intergenic transcribed spacers (ITS) and metabolic fingerprinting showed great differences between hemispheres but also between neighboring glaciers. Phylogenetic distance between Arctic and Antarctic isolates indicated separate species. The Arctic group clustered similarly, when constructing dendrograms based on 16S rRNA gene and ITS sequences, as well as metabolic traits. The Antarctic strains, although almost identical considering 16S rRNA genes, diverged into 2 groups based on the ITS sequences and metabolic traits, suggesting recent niche separation. Certain phenotypic traits pointed towards cell adaptation to specific conditions on a particular glacier, like varying pH levels. Collected data suggest, that seeding of glacial surfaces with Polaromonas cells transported by various means, is of greater efficiency on local than global scales. Selection mechanisms present of glacial surfaces reduce the deposited Polaromonas diversity, causing subsequent adaptation to prevailing environmental conditions. Furthermore, interactions with other supraglacial microbiota, like algae cells may drive postselectional niche separation and microevolution within the Polaromonas genus.

The mineral framework and pore waters of glacial sediments exposed in the foreland of Weren- skioldbreen in SW Spitsbergen were sampled and analyzed to model the evolution of pore water chemistry, representing the advancement of weathering in a chronosequence. Three samples were taken at distances representing snapshots of approximately 5, 45 and 70 years of exposure. Complementary mineralogical analyses of the mineral framework and chemical analyses of pore waters, coupled with thermodynamic modelling of mineral-water interactions were applied. Recently uncovered sediments of the bottom moraine underwent very little weathering underneath the glacier cover; both the sediments and pore waters in the forefield of the Werenskioldbreen represent a very immature system. Poorly sorted sediments were deposited by the glacier and not reworked by fluvioglacial waters. The ratio of ‘amorphous iron’ to ‘free iron’ Feo/Fed increases with distance from the glacier terminus from 0.30 through 0.36 to 0.49, typical for fresh glacial till. The increase in saturation with CO₂ (from p(CO₂) –3.8 to –2.4) and the concentration of all major ions in pore waters (from 123 to 748 mg/L total dissolved solids, TDS) was observed in this young chronosequence. The waters evolved from carbonate- dominated to sulphate-dominated, indicating that with progress in weathering the dominating processes are equilibration with carbonates, oxidation of sulphides and the influence of gypsum precipitation by seasonal freeze-thaw cycles. Mass balance calculations and inverse modelling of the composition of pore waters, verified by microscopic observations of alteration on the surfaces of mineral grains, allowed thermodynamic confirmation of the fact that the relative significance of carbonate weathering decreases and that of sulphate increases down the chronosequence. The participation of silicate minerals in weathering is low, indicating a relatively immature stage of weathering within this particular chronosequence. It is significant that the morphology of etch pits and the formation of secondary phases apparent on mineral surfaces were identical, regardless of the distance from the glacier terminus. This might indicate that the mechanisms of particular weathering processes at the mineral-water interface are the same at the initial as well as at the more mature stages and do not change at least within ca. 70 years of exposure.

Surface ice and cryoconite holes of two types of polythermal Svalbard Glaciers (Hans Glacier—grounded tidewater glacier and Werenskiold Glacier—land-based valley glacier) were investigated in terms of chemical composition, microbial abundance and diversity. Gathered data served to describe supraglacial habitats and to compare microbe–environment interactions on those different type glaciers. Hans Glacier samples displayed elevated nutrient levels (DOC, nitrogen and seston) compared to Werenskiold Glacier. Adjacent tundra formations, bird nesting sites and marine aerosol were candidates for allochtonic enrichment sources. Microbial numbers were comparable on both glaciers, with surface ice containing cells in the range of 10⁴ mL⁻¹ and cryoconite sediment 10⁸ g⁻¹ dry weight. Denaturating gradient gel electrophoresis band-based clustering revealed differences between glaciers in terms of dominant bacterial taxa structure. Microbial community on Werenskiold Glacier benefited from the snow-released substances. On Hans Glacier, this effect was not as pronounced, affecting mainly the photoautotrophs. Over-fertilization of Hans Glacier surface was proposed as the major factor, desensitizing the microbial community to the snow melt event. Nitrogen emerged as a limiting factor in surface ice habitats, especially to Eukaryotic algae.

The diversity of polyhydroxyalkanoates-producing bacteria in freshwater reservoirs in the Ecology Glacier foreland, Antarctica, was examined by a cultivation-dependent method. Isolated strains were analyzed phylogenetically by 16S rRNA gene sequencing, and classified as members of Alpha-, Beta-, or Gammaproteobacteria classes. Polymerase chain reaction was used to detect PHA synthase genes. Potential polyhydroxyalkanoates (PHAs) producers belonging mainly to Pseudomonas sp., and Janthinobacterium sp. were isolated from all five sampling sites, suggesting that PHA synthesis is a common bacterial feature at pioneer sites. All Pseudomonas strains had the genetic potential to synthesize medium-chain-length PHAs, whereas some isolated Janthinobacterium strains might produce short-chain-length PHAs or medium-chain-length PHAs. It is the first report revealing that Janthinobacterium species could have the potential to produce medium-chain-length PHAs.