Cyanobacteria are photoautotrophic bacteria that perform oxygenic photosynthesis. They were at the basis of the oxygenation of the atmosphere 2.3 billion years ago that allowed the appearance of more complex organisms and have played a unique role in the evolution of life on earth. Moreover, they were the ancestors of plastids by endosymbiosis. Nowadays, cyanobacteria are the dominant photoautotrophs in the terrestrial and non-marine Antarctic biotopes. The University of Liège collection includes 107 unicyanobacterial polar strains coming from different regions of Antarctica (South Victoria Land, Eastern Antarctica, Transantarctic Mountains) and the Arctic (Northern Canada, Arctic Ocean, Alaska) and different biotopes (microbial mats, lakes, ice shelves, dry valleys, endolithic habitats, ocean water). Moreover, 12 strains come from sub-Arctic Siberian lakes. The three most importantorders of cyanobacteria (Chroococcales Oscillatoriales, Nostocales) are represented.

In addition, the host laboratory is participating in several studies on the diversity of polar cyanobacteria (BELSPO projects AMBIO, ANTAR-IMPACT, BELDIVA and HOLANT), and new strain isolations are in progress. The origins of these new strains are the region of the new Belgian Antarctic Station "Princess Elisabeth" and Schirmacher Oasis (Dronning Maud Land), Syowa Oasis (Eastern Antarctica), and Svalbard (Arctic). They will broaden the geographic and ecological coverage of the collection. Most of the isolates are psychrotolerant and can be cultivated at 20°C. They are available as living cultures, and the majority (98) are also cryo-preserved (-70°C).
The cyanobacThe cyanobacteria in general are important microbial sources of molecules for biotechnological and pharmaceutical research. Many types of activities (antibiotic, anticancer, antiviral, etc.) have been described in the literature ^18,19,20. Recent progress in genomics and proteomics is opening new ways to exploit this metabolic capacity to create cyanobacterial ‘cell factories ^21,22,  which are also emphasized by the EC network ALGINET (http://www.biomatnet.org/secure/FP5/S1617.htm).
The initial pharmaceutical screening of a part of our collection has been completed.^23,24 Notwithstanding slow growth, 48 strains were tested. About 120 chemically diverse extracts were generated from these strains and screened by means of antimicrobial assays and cytotoxicity tests. This has shown that 17 strains are bioactive against the Gram-positive Staphylococcus aureus or the fungi Aspergillus fumigatus and Cryptococcus neoformans, and 25 are cytotoxic against HeLa cells. The bioactivities were found to be not in function of phylogenetic relationships but were strain-specific.

Because the extreme environmental conditions of the polar biotopes probably have selected particular genotypes and because our molecular data indicate the existence of Antarctic endemism, it is probable that the polar cyanobacteria contain molecules and enzymes with interesting tolerances (cold temperature, salinity, etc.). There is also an interest in the use of polar strains for wastewater treatment in cold regions.²⁵ Moreover, UV-protecting pigments like scytonemin or molecules like the mycosporins may well have applications.
Last but not least, studies of molecular signatures for life in fossil rocks from earth or other planets²⁶ can benefit from a better knowledge of the taphonomy of cyanobacteria, and of the molecular traces left after their fossilization. They have had a major impact on the geological and biological evolution of Earth. The dating of their appearance and of ancient fossils is still under discussion. Sophisticated micro-techniques are now being used to identify biochemical and ultrastructural biomarkers and to study how the fossilisation processes modify or preserve them.
The collection is also contributing to the Antarctic research carried out by Belgium under its obligations as a signatory to the Antarctic Treaty (http://www.belspo.be/belspo/BePoles/science/index_en.stm)

Literature

18. Soltani N, Khavari-Nejad RA, Tabatabaei Yazdi M, Shokravi Sh, Fernandez-Valiente E (2005) Screening of soil cyanobacteria for antifungal and antibacterial Activity. Pharmaceutical BiologyBiology 43: 455-459.
19. Wagoner van RM, Drummond AK, Wright JLC (2007) Biogenetic Diversity of Cyanobacterial Metabolites. Advances in Applied Microbiology 61: 89-217.
20. Gademann K, Portmann C (2008) Secondary metabolites from Cyanobacteria: complex structures and powerful activities. Current Organic Chemistry 12: 326-341.
21. Burja AM, Dhamwichukorn S, Wright PC (2003) Cyanobacterial postgenomic research and systems biology. Trends in Biotechnology 21: 504-511.
22. Angermayr SA, Hellingwerf KJ, Lindblad P, Teixeira de Mattos MJ (2009) Energy biotechnology with cyanobacteria. Current Opinion in Biotechnology 20:257-263.
23. Taton A, Grubisic S, Balthasart P, Hodgson DA, Laybourn-Parry J, Wilmotte A (2006) Biogeographical distribution and ecological ranges of benthic cyanobacteria in East Antarctic lakes. FEMS Microbiology Ecology 57:272-289.
24. Biondi N, Tredici MR, Taton A, Wilmotte A, Hodgson DA, Losi D, Marinelli F (2008) Cyanobacteria from benthic mats of Antarctic lakes as a source of new bioactivities. Journal of Applied Microbiology 105:105-115.
25. Chevalier P, Proulx D, Lessard P, Vincent WF, de la Noüe J (2000) Nitrogen and phosphorus removal by high latitude mat-forming cyanobacteria for potential use in tertiary wastewater treatment, Journal Applied Phycology 12:105-112.
26. Wynn-Williams DD, Edwards HGM (2000) Antarctic ecosystems as models for extraterrestrial surface habitats. Planetary and Space Science 48:1065-1075.

Contacts

Annick Wilmotte (awilmotte@ulg.ac.be)

Collection of Polar Cyanobacteria
Centre for Protein Engineering
Liège University
Sart Tilman B6
B-4000 Liège
Tel: +32 (0)4 366 38 56
Fax: +32 (0)4 366 33 64