Antarctic cyanobacterial diversity in the BCCM/ULC collection as useful and sustainable resource for research

anglais. On the Antarctic continent, Cyanobacteria represent key primary producers. They build extensive benthic microbial mats in lakes and soil crusts in terrestrial biotopes. They may present interesting adaptations to survive freeze/thaw cycles, seasonally contrasted light intensities, high UV radiations, dessication and other stresses. The genetic mechanisms of this resistance only start to be unraveled. The BCCM/ULC public collection presently includes 140 Antarctic cyanobacterial strains and its catalogue is available on https://bccm.belspo.be/catalogues/catalogue-search?collection=ULC. An ISO9001 certificate was obtained for the public deposition and distribution of strains. The purpose of this collection is to gather a representative sample of Antarctic cyanobacterial diversity from different biotopes (limnetic microbial mats, soil crusts, cryoconites, endoliths, etc.) and make it available for researchers to study the diversity, evolution, ecophysiology, and genomic make-up. This is particularly important in view of the emerging use of metagenomic approaches on environmental samples, where the comparison with well-characterized strain genome sequences is very useful. As a small piece of natural samples is sufficient to isolate a large number of strains, culture collections are a sustainable option to give access to microbial biodiversity without the environmental costs of field trips and cumulative sample collections. We carried out a genomic study of two BCCM/ULC Antarctic strains of the Laspinema genus, with a simple filamentous morphology. A phylogenomic analysis showed that they form a new species with the genome of strain FRX01, and all were collected in lakes of the McMurdo Ice Shelf or Dry Valleys. Genome mining showed that the Biosynthetic Gene Clusters are less diverse in Antarctic strains relative to their temperate relatives, and share terpenes and siderophores with the latter. A search of the functional genes detected 115 specific genes for the Antarctic Laspinema genus, but no function could be attached to them (dark matter), showing the need for better genetic knowledge.

14. Life below water

15. Life on land