Linking environmental heterogeneity and chemo-diversity in cyanobacteria: A culture-dependent profile based analysis

Cyanobacteria are ecologically versatile microorganisms that inhabit most environments, ranging from marine systems to arid deserts. Given their ability to survive under harsh and extreme conditions, we hypothesize that cyanobacteria could produce a wide variety of compounds in specific niches. In this context, we sampled a number of different environments, from freshwater and brackish ecosystems to terrestrial and anchialine caves, spanning from the Canary Islands and Iceland to Estonia and Greece. Forty-four (44) cyanobacteria strains were analyzed with de novo peptide fragmentation in order to detect their metabolome profile; further, their antimicrobial, cytotoxic, and enzyme inhibitory activity was investigated. Both freshwater/planktic and rock-dwelling/benthic strains exhibited different types of inhibitory activities. However, cyanopeptides were only detected in freshwater strains; microcystins, anabaenopeptins, and aeruginosins congeners from Microcystis spp., Thrichormus variabilis, and Calothrix epiphytica strains. Therefore, our results indicate a high degree of unknown chemo-diversity, as we could not link the presence/absence of any known cyanopeptides and inhibitory activities from strains derived from other habitats, in contrast with freshwater cyanobacteria strains. In this work we discuss the correlation between the cyanobacteria chemo- and lifestyle diversity providing a missing study material for profile-based analysis on cyanobacteria from under-explored environments