Exopolysaccharides of Synechocystis aquatilis are sulfated arabinofucans containing N-acetyl-fucosamine

Cyanobacteria are known to be a rather diverse group of organisms regarding e.g. morphology, metabolism and composition of excreted exopolysaccharides (EPS). Considering the high number of known cyanobacterial species the EPS from only a small percentage are investigated in detail. This work examined EPS from the unicellular strains of Synechocystis aquatilis and S. pevalekii with various methods. The results emphasize the heterogeneity of cyanobacterial EPS. S. pevalekii secrets complex hetero-polysaccharides and acidic proteins as proteoglycan-complexes whereas the protein-free but highly sulfated EPS from S. aquatilis only consist of 4 dominant monosaccharides. Especially remarkable is the composition of these EPS: an arabinofucan with higher amounts of N-acetyl-fucosamine (FucNAc) and only minor quantities of glucose. Both EPS and the newly found component FucNAc in EPS from S. aquatilis extend the possible components of cyanobacterial EPS and the knowledge of heterogeneity of cyanobacterial metabolites.