LAUSR

Abstract Cyanobacteria have the ability to produce a wide variety of natural bioactive compounds. In order to reveal the diversity of Cyanobacteria in Iran, and their potential to synthesise various natural products, we isolated 25 strains from different climatic/geographic regions and habitats, and screened the genes that are responsible for the synthesis of natural products (such as nonribosomal peptide synthetase or polyketide synthase and 4-methylproline) by means of PCR. In addition, we analysed adenylation domain substrate specificity from screened NRPS fragments in order to identify peptidic molecules that are produced by the studied strains. The phylogenetic analysis showed the widespread, but sporadic, occurrence of the methylproline biosynthetic pathways in these strains. Our results do not only reveal the chemical diversity that is occurring in these Cyanobacteria of Iran that we isolated, but they also indicate that 4-methylproline biosynthetic genes have a complex evolutionary history in Cyanobacteria, which has been punctuated by a series of ancient horizontal gene transfer events.