A detailed morphological, phylogenetic and ecophysiological analysis of four benthic Anabaena (Nostocales, Cyanobacteria) strains confirms deep heterogeneity within the genus

Four benthic Anabaena strains isolated from different localities in the Czech Republic were examined from the morphological, phylogenetic, and physiological points of view. The results of combined analysis showed distinct morphological dissimilarity between the studied strains, which were further found to belong to different phylogenetic groups based on the 16S rRNA gene phylogeny. To assess the temperature and light (irradiance) optima of the strains, we exposed them to various combinations of these two parameters. The experiment revealed unexpectedly high temperature and light optima for some of the strains, while others showed optima that were similar to those of previously studied planktic species of related heterocytous genera. Our study is the first of its kind to be applied to benthic Anabaena strains. Our results indicate that the benthic Anabaena genus is much more complex than previously thought and provide novel insights into the biology and ecology of benthic Anabaena species. With the collection of more data, we expect the genus Anabaena will be split into several new monophyletic taxa, each covering distinct morpho- and ecotypes.