Highest diversity of cyanobacterial on granite substrates in the Sør Rondane Mountains

In the Sør Rondane Mountains (Dronning Maud Land, East Antarctica), cyanobacteria are mainly present in sheltered spots in rocky areas, supporting the importance of micro-topographic and -climatic conditions. Biofilms, crusts and gravels on granite and gneiss substrates were sampled in 2009-2010 near the Belgian Princess Elisabeth Station and their morphological (126 samples) and molecular diversity (26 samples) was assessed. A DNA extraction protocol was designed for the taxa with large polysaccharidic sheaths. Based on microscopy, crusts were the richest samples followed by gravels. The most diverse communities were found on the granites. Based on DGGE of 16S rRNA gene, 28 OTUs shared at least 97.5% of 16S rRNA similarity. OTUs’ richness varied between 1 and 5 per sample. A comparison of morphological and DGGE analyses showed that for most samples, the number of morphotypes was higher than the number of OTUs. However, both methods were congruent in defining the richest sites. The most frequently observed OTU was affiliated to Phormidium/Microcoleus sp. No OTU was common to all the 10 sites. The higher diversity on granite substrates (mainly big boulders) could be explained by higher stability of the underlaying rock and its ability to keep water on the surface, thus creating favorable conditions for development of organisms. Further insights will be given by the analysis of more samples with High-Throughput amplicon sequencing.