CAROTENOIDS AND MYCOSPORINE-LIKE AMINO-ACID COMPOUNDS IN MEMBERS OF THE GENUS MICROCOLEUS (CYANOBACTERIA) - A CHEMOSYSTEMATIC STUDY

We determined the patterns of occurrence of carotenoids and mycosporin e-like amino acid compounds among 21 cyanobacterial isolates, variousl y ascribed to the genus Microcoleus, and used them as chemotaxonomical markers. All strains fitting the morphological and ecological descrip tion of M. chthonoplastes had a remarkably similar pattern of caroteno ids and mycosporine-like amino acids (MAAs), regardless of their geogr aphical origin. This supports the notion that these isolates represent a phylogenetically coherent group. However, small variations in the s ugar moiety of their myxoxanthophylls and the occurrence of novel myco sporine-like amino acid compounds indicate some degree of either bioge ographical or ecotypic diversification. The M. chthonoplastes-group of strains could easily be differentiated on the basis of the presence o f the carotenoids echinenone, isozeaxanthin, zeaxanthin and various MA As from all other isolates fitting the morphological and ecological de scriptions of M. sociatus, M. paludosus, and M. lacustris, as well as other strains of uncertain affiliation, which have been assigned to Mi crocoleus in the literature. Our study demonstrates the applicability of the chemotaxonomy with carotenoids and mycosporines in solving prob lematic questions in low-rank cyanobacterial systematics.