Comparison of Arctic and Antarctic microbial communities: abundance, phylogeny and ecology
Final Report Abstract
Cold terrestrial habitats of the Antarctic or the High Arctic are exposed to extreme environmental conditions with a wide temperature gradient and repeated freeze-thaw cycles. They are characterized by the presence of permanently frozen ground, so-called permafrost, and mainly low nutrient concentrations. The uppermost soil layer, referred to as active layer, thaws in summer to a depths of only a few centimeters to several decimeters. The knowledge about the diversity and adaptation potentials of microorganisms from cold soil environments is still limited. This project that is integrated within the scope of international research activities aimed for investigating the microbial diversity and activity of Arctic and Antarctic terrestrial habitats. To approach this, both culture-dependent and culture-independent methods were applied. The particular objectives of this work were to study the diversity of the dominant bacterial groups from soils of Livingston Island (maritime Antarctic), to identify possible influences of different soil parameters on these bacterial communities, and to undergo isolation, cultivation and phylogenetic characterization of heterotrophic bacteria from soils of Northeast Greenland. Furthermore, three bacterial isolates from Livingston Island (maritime Antarctic) and one bacterial isolate from Northeast Greenland were analysed biochemically and physiologically more in detail. The dominant bacterial groups of the investigated soils of Livingston Island were identified as Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Gemmatimonadetes, Nitrospirae, Planctomycetes and Proteobacteria. Thereby, Acidobacteria and Bacteroidetes were the most abundant. The moss-covered sites that are characterized by nutrient-rich, acidic conditions were dominated by members of the Bacteroidetes. The unvegetated sites characterized by nutrient-poor conditions with a neutral to alkaline pH regime were dominated by members of the phylum Acidobacteria, Interestingly, also a significant number of unclassified bacterial sequences (up to 25%) were obtained for individual investigation sites. Statistical analyses indicated that high carbon and nitrogen concentrations and a low pH favours a Bacteroidetes-dominated community, whereas neutral pH conditions and a higher clay and silt content seem to favour members of the Acidobacteria. Altogether, 213 heterotrophic, aerobic bacterial strains were isolated from different soils from Northeast Greenland that could be assigned to 65 different operational taxonomic units (OTU) having a 16S rRNA gene sequence similarity of ≥ 98.5%. They were mainly affiliated to the phyla Actinobacteria and Proteobacteria, but also members of the Bacteroidetes and Firmicutes were isolated. Over 50% of the OTUs were closely related to isolates from other cold environments from the Arctic, Antarctic and high alpine areas like Tibet, the Himalaya or the Tianshan mountains. Furthermore, bacteria belonging to the nitrogen-fixing genera Brady rhizobium, Mesorhizobium and Rhizobium were isolated which likely contribute to overcome the prevailing nitrogen limitations in minor-developed, nutrient-poor soils of low temperature environments. Four novel bacterial isolates were described in more detail. All new strains belonged to the phylum Actinobacteria and were related to the genera Arthrobacter, Leifsonia and Cryobacterium. These novel isolates were named Arthrobacter livingstonensis, Arthrobacter cryotolerans, Leifsonia psychrotolerans and Cryobacterium arcticum. The strains were able to grow at subzero temperatures down to -6°C. They also tolerate a wide pH range from acidic to alkaline pH and high salt concentrations. All of the strains, except Arthrobacter cryotolerans, were able to metabolize a wide variety of organic compounds. Based on the results of this project, it can be ascertained that soils from maritime Antarctica and Northeast Greenland inhabit a diverse bacterial community. If due to climate change the mean annual temperatures will rise in the maritime Antarctic as predicted, the spreading of plants, especially mosses, are likely to cause a shift in the soil microbial community from oligotrophic bacteria to a community of degraders, able to use high-molecular compounds. Based on this work, it is suggested that Northeast Greenland soils inhabit bacterial species that are globally distributed in regions with comparable climatic conditions. According to the novel isolates described in the frame of this thesis, those bacteria are very well adapted to the extreme conditions of polar soil environments.
Publications
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(2006) Bulgarian-German Expedition: LIVINGSTON 2005. (2006) Bulgarian-
German Expedition: LIVINGSTON 2005. Reports on Polar and Marine Research 539, pp. 91 -123. (Expedition Report)
Wagner, D., Schwammbom, G., Hubberten, H.-W., Pimpirev, C.
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(2007). Microbial communities in different Antarctic mineral deposits characterised by denaturing gradient gel electrophoresis (DGGE). lOth
Intemational Symposium on Antarctic Earth Sciences (ISAES), University of Califomia, Santa Barbara, USA, August 26-31, 2007.
Ganzert, L., Wagner, D.
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(2008) Microbial communities from terrestrial mineral soils from Livingston Island, maritime Antarctica, 3rd Intemational Conference
on Polar and Alpine Microbiology, Banff, Canada, May 11-15, 2008.
Ganzert L., Lipski A., Wagner D.
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(2008) The use of GPR to detect active layer in young periglacial terrain of Livingston Island, Maritime Antarctica. Near Surface Geophysics, Vol 6. 2008, No 5, pp. 331 - 336.
Schwammbom G., Wagner D. and Hubberten H.-W.
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(2009) Bacterial communities from mineral soils located on Livigston Island, South Shetland Islands, Antarctica. VAAM Annual Meeting, March 8-11, 2009, Bochum, Germany.
Ganzert L. Lipski A., Pimpirev C, Hubberten H.-W., Wagner D.
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(2010) Isolation and characterization of heterotrophic microorganisms from mineral soils of Livingston Island (Antarctica) and Store Koldewey (Northeast-Greenland). VAAM Annual Meeting, March 28-31, 2010, Hannover, Germany
Bajerski F., Ganzert L., Mangelsdorf K., Lipski A. and Wagner D.
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(2010) Thermal state of permafrost and active-layer monitoring in the Antarctic: advances during the Intemational Polar Year 2007-2009.
Permafrost and Periglacial Processes. Special Issue: The International Polar Year, Vol. 21. 2010, Issue 2, pages 182–197.
Vieira G., Bockheim J., Guglielmin M., Balks M., Abramov A.A., Boelhouwers J., Cannone N., Ganzert L., Gilichinsky D., Goryachkin S., Lopez-Martinez J., Meiklejohn I., Raffi R., Ramos M., Schaefer C, Serrano E., Simas F., Sletten R., Wagner D.
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(2011) Arthrobacter livingstonensis sp. nov. and Arthrobacter cryotolerans sp. nov., salt- and psychrotolerant species isolated from Livingston Island, Antarctica. International Journal of Systematic
and Evolutionary Microbiology, Vol. 61. 2011, pp.979-984.
Ganzert L., Bajerski F., Mangelsdorf K., Lipski A. and Wagner D.
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(2011) Cryobacterium arcticum sp. nov., a novel psychrotolerant bacterium from an arctic soil. International Journal of Systematic and Evolutionary Microbiology, Vol. 61. 2011, pp. 1849-1853.
Bajerski F., Ganzert L., Mangelsdorf K., Lipski A. and Wagner D.
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(2011) Leifsonia psychrotolerans sp. nov., a psychrotolerant species of the family Microbacteriaceae from Livingston Island, Antarctica. International Journal of Systematic and Evolutionary Microbiology 61. 2011, issue 8, pp. 1938-1943.
Ganzert L., Bajerski F., Mangelsdorf K., Lipski A. and Wagner D.
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(2011) The impact of different soil parameter on the diversity of dominant bacteria from nine different soils located on Livingston Island, South Shetland Archipelago, Antarctica. FEMS Microbiology Ecology, Vol. 76. 2011, Issue 3, pp. 476–491.
Ganzert L., Lipski A., Hubberten H.-W. and Wagner, D.
