Abstract :
[en] In the Polar Regions, Cyanobacteria represent key primary producers and are the main drivers of the food webs in a wide range of aquatic to terrestrial habitats. They build benthic microbial mats in lakes and soil crusts in terrestrial biotopes. They may present interesting features to survive freeze/thaw cycles, seasonally contrasted light intensities, high UV radiations, dessication and other stresses.
The BCCM/ULC public collection funded by the Belgian Science Policy Office since 2011 aims to gather a representative portion of the polar cyanobacterial diversity with different ecological origins (limnetic mats, soil crusts, cryoconites, endoliths…). It makes it available for researchers to study the taxonomy, evolution, adaptations to harsh environmental conditions, and genomic make-up. It presently includes 224 cyanobacterial strains, with 140 being of Antarctic origin (catalogue: http://bccm.belspo.be/catalogues/ulc-catalogue-search). An ISO 9001 certificate was obtained for the public deposition and distribution of strains, as part of the multi-site certification for the BCCM consortium.
The morphological identification shows that the strains belong to the orders Synechococcales, Oscillatoriales, Pleurocapsales, Chroococcidiopsidales and Nostocales. The 16S rRNA and ITS sequences of the strains are gradually being characterized. The 159 BCCM/ULC strains for which 16S rRNA sequences were analyzed correspond to 69 OTUs (sequences with > 99 % 16S rRNA similarity), and thus, represent a quite large diversity.
In addition, cyanobacteria are known to produce a wide range of secondary metabolites (e.g. alkaloids, cyclic and linear peptides, polyketides) with bioactive potential. Genome sequencing was performed for 15 strains (Lara et al. 2017, Cornet et al. 2018). The bioinformatic analysis of the partial genomes of strains ULC007, ULC065 and ULC129 showed the presence of clusters encoding NRPS, PKS, hybrid clusters and other types of secondary metabolites. The comparison of a selection of the PEGs involved in the cold adaptation mechanisms revealed that more copies of PEGs involved in various molecular mechanisms of cold stress responses have been found in polar than in non polar genomes.
In summary, the BCCM/ULC public collection serves as a Biological Resource Centre to conserve ex situ and document the biodiversity of polar cyanobacteria, as well as a repository for discovery of novel bioactive compounds.
