Ex-situ’ conservation of Antarctic cyanobacteria : a culture collection to explore diversity and bioactivity

Cyanobacteria appear as the dominant phototrophs in Antarctic terrestrial and freshwater ecosystems. Since 2011, the Belgian Science Policy Office has funded the BCCM/ULC public collection of (sub)polar cyanobacteria. It is currently holding 102 Antarctic cyanobacterial strains and the catalogue is available on http://bccm.belspo.be/db/ulc_search_form.php. A Quality Management System was implemented and an ISO9001 certificate was obtained for the public deposition and distribution of strains. The strains are kept as living cultures, and their cryopreservation is in progress.

The Antarctic cyanobacterial strains were isolated from samples of the three main biogeographic provinces. The purpose of this public collection is to gather a representative portion of the cyanobacterial diversity with different ecological origins (limnetic microbial mats, soil crusts, cryoconites, endoliths, etc.) and make it available for researchers to study the diversity, evolution, adaptations to the environmental conditions, and genomic make-up. Three cyanobacterial orders are represented: Chroococcales, Oscillatoriales and Nostocales. This is particularly important in view of the emerging use of metagenomic approaches on environmental samples, where the comparisons with the genome sequences from well-defined strains is very useful. They could also serve as references for compounds such as fatty acids and pigments.

In addition, cyanobacteria produce a range of secondary metabolites (e.g. alkaloides, cyclic and linear peptides, polyketides) with different bioactive potential (e.g. antibiotic, antiviral, anticancer, cytotoxic, genotoxic). Bioassays have shown antifungal activities of the cell extracts of strains Plectolyngbya hodgsonii ULC009 and Phormidium priestleyi ULC026. Due to the geographic isolation and the strong environmental stressors of the habitat, the exploration of these metabolites in Antarctic cyanobacterial strains seems especially promising for biotechnology or biomedical applications.

In summary, the BCCM/ULC public collection could serve as a general reference for Antarctic cyanobacteria with multiple applications, as well as a resource for novel bioactive compounds.