Antarctic glacier forefields are extreme environments and pioneer sites for ecological succession. Increasing temperatures due to global warming lead to enhanced deglaciation processes in cold-affected habitats, and new terrain is becoming exposed to soil formation and microbial colonization. However, only little is known about the impact of environmental changes on microbial communities and how they develop in connection to shifting habitat characteristics. In this study, using a combination of molecular and geochemical analysis, we determine the structure and development of bacterial communities depending on soil parameters in two different glacier forefields on Larsemann Hills, East Antarctica. Our results demonstrate that deglaciation-dependent habitat formation, resulting in a gradient in soil moisture, pH and conductivity, leads to an orderly bacterial succession for some groups, for example Cyanobacteria, Bacteroidetes and Deltaproteobacteria in a transect representing 'classical' glacier forefields. A variable bacterial distribution and different composed communities were revealed according to soil heterogeneity in a slightly 'matured' glacier forefield transect, where Gemmatimonadetes, Flavobacteria, Gamma- and Deltaproteobacteria occur depending on water availability and soil depth. Actinobacteria are dominant in both sites with dominance connected to certain trace elements in the glacier forefields.

Microorganisms in Antarctic glacier forefields are directly exposed to the hostile environment of their habitat characterized by extremely low temperatures and changing geochemical conditions. To survive under those stress conditions microorganisms adapt, among others, their cell membrane fatty acid inventory. However, only little is known about the adaptation potential of microorganisms from Antarctic soil environments. In this study, we examined the adaptation of the cell membrane polar lipid fatty acid inventory of Chryseobacterium frigidisoli PB4T in response to changing temperature (0°C to 20°C) and pH (5.5 to 8.5) regimes, because this new strain isolated from an Antarctic glacier forefield showed specific adaptation mechanisms during its detailed physiological characterization. Flavobacteriaceae including Chryseobacterium species occur frequently in extreme habitats such as ice-free oases in Antarctica. C. frigidisoli shows a complex restructuring of membrane derived fatty acids in response to different stress levels. Thus, from 20°C to 10°C a change from less iso-C15:0 to more iso-C17:1ω7 is observed. Below 10°C temperature adaptation is regulated by a constant increase of anteiso-FAs and decrease of iso-FAs. An anteiso- and bis-unsaturated fatty acid, anteiso-heptadeca-9,13-dienoic acid, shows a continuous increase with decreasing cultivation temperatures underlining the particular importance of this fatty acid for temperature adaptation in C. frigidisoli. Concerning adaptation to changing pH conditions, most of the dominant fatty acids reveal constant relative proportions around neutral pH (pH 6–8). Strong variations are mainly observed at the pH extremes (pH 5.5 and 8.5). At high pH short chain saturated iso- and anteiso-FAs increase while longer chain unsaturated iso- and anteiso-FAs decrease. At low pH the opposite trend is observed. The study shows a complex interplay of different membrane components and provides, therefore, deep insights into adaptation strategies of microorganisms from extreme habitats to changing environmental conditions.

Greenland is one of the regions of interest with respect to climate change and global warming in the Northern Hemisphere. Little is known about the structure and diversity of the terrestrial bacterial communities in ice-free areas in northern Greenland. These soils are generally poorly developed and usually carbon- and nitrogen-limited. Our goal was to provide the first insights into the soil bacterial communities from five different sites in Northeast Greenland using culture-independent and culture-dependent methods. The comparison of environmental and biological data showed that the soil bacterial communities are diverse and significantly pH-dependent. The most frequently detected OTUs belonged to the phyla Acidobacteria, Bacteroidetes and (Alpha-, Beta-, Delta-) Proteobacteria. Low pH together with higher nitrogen and carbon concentrations seemed to support the occurrence of (Alpha-, Beta-, Delta-) Proteobacteria (at the expense of Acidobacteria), whereas Bacteroidetes were predominant at higher values of soil pH. Our study indicates that pH is the main factor for shaping bacterial community, but carbon and nitrogen concentrations as well may become important, especially for selecting oligotrophic microorganisms.

Two novel cold-tolerant, Gram-stain-positive, motile, facultatively anaerobic bacterial strains, LI2 T and LI3 T , were isolated from moss-covered soil from Livingston Island, Antarctica, near the Bulgarian station St Kliment Ohridski. A rod-coccus cycle was observed for both strains. 16S rRNA gene sequence analysis revealed an affiliation to the genus Arthrobacter, with the highest similarity to Arthrobacter stackebrandtii and Arthrobacter psychrochitiniphilus for strain LI2 T (97.8and 97.7 % similarity to the respective type strains) and to Arthrobacter kerguelensis and Arthrobacter psychrophenolicus for strain LI3 T (97.4 and 97.3 % similarity to the respective type strains). The growth temperature range was "6 to 28 6C for LI2 T and "6 to 24 6C for LI3 T , with an optimum at 16 6C for both strains. Growth occurred at 0-10 % (w/v) NaCl, with optimum growth at 0-1 % (w/v) for LI2 T and 0.5-3 % (w/v) for LI3T . The pH range for growth was pH 4-9.5 with an optimum of pH 8 for LI2T and pH 6.5 for LI3T . The predominant fatty acids were anteiso-C 15 : 0 , C 18 : 0 and anteiso-C 17 : 0 for LI2 T and anteiso-C 15 : 0 and C 18 : 0 for LI3

A psychrotolerant, Gram-stain-positive, yellow-pigmented, aerobic rod, designated SK1 T , was isolated from a soil sample collected from Store Koldewey, north-east Greenland. Cells were catalase-and methyl red-positive, produced H 2 S and produced acid from glucose, mannitol and salicin. Strain SK1 T was able to grow between "6 and 28 6C, with an optimum at 20 6C. The isolate contained 2,4-diaminobutyrate, glycine, alanine and glutamic acid in the cell wall and the major menaquinones were MK-10 and MK-11. Identified polar lipids were phosphatidylglycerol and diphosphatidylglycerol. The major fatty acids were anteiso-C 15 : 0 (53.5 %), anteiso-C 17 : 0 (17.0 %) and C 18 : 0 (12.1 %). The genomic DNA G+C content was 67.8 mol%. Strain SK1 T showed the highest 16S rRNA gene sequence similarity with Cryobacterium psychrotolerans 0549 T (97.6 %) and Cryobacterium roopkundense RuGl7 T (96.8 %). Considering morphological, physiological, biochemical and chemotaxonomic characters and phylogenetic analysis, strain SK1 T represents a novel species in the genus Cryobacterium, for which the name Cryobacterium arcticum sp. nov. is proposed. The type strain is SK1 T (5DSM 22823 T 5NCCB 100316 T ).The genus Cryobacterium was first described by Suzuki et al. (1997) to accommodate psychrophilic Gram-positive irregular rods. The type species, Cryobacterium psychrophilum, had been isolated from an Antarctic soil sample by Inoue & Komagata (1976) and was originally named 'Curtobacterium psychrophilum'. Currently, the genus comprises only three other known species: Cryobacterium psychrotolerans, isolated from the China No. 1 glacier by Zhang et al. Within the scope of ecological studies of microbial communities in extreme polar environments, several cold-adapted aerobic bacteria were isolated from mineral soils on Store Koldewey, north-east Greenland. Strain SK1 T was isolated from a soil sample from the bottom of a slope on the shore of Duck Lake, Store Koldewey (76 u 259 N 18 u 449 W). Nutrient agar (0.5 % peptone, 0.3 % meat extract, 0.1 % yeast extract, 0.5 % glucose, 1.5 % agar, all w/v, in deionized water; pH 7.2) was used for isolation. The isolate was maintained at 16 uC on half-diluted LB medium (0.5 % tryptone, 0.25 % yeast extract, 0.5 % NaCl, 1.5 % agar for solid medium, all w/v, in deionized water; pH 7.2). The same conditions and media were used for all experiments, unless otherwise noted.Colony characteristics were determined visually after incubation for 7 and 14 days. Cell morphology was examined by light microscopy (Axioskop 2 Plus; Zeiss) after incubation for 2 days. Gram staining was carried out by the classical procedure as described by Gram (Schröder, 1991). The presence of flagella was determined in the way of Leifson (Schröder, 1991). Spores were detected according to Wirtz (Schröder, 1991). Conditions for growth were determined between 26 and 32 u C, with 0-10 % (w/v) NaCl and at pH 4-10. The medium was buffered with glycine (pH 4.0-5.0 and pH 10.0), MES (pH 5.0-6.5), HEPES (pH 7.0-8.0) or Bis Tris propane (p...