Browsing by Subject "biosynthetic gene cluster"

Mycosporines and mycosporine-like amino acids (MAAs) are ultraviolet-absorbing molecules produced by a range of photosynthetic microorganisms upon exposure to solar ultraviolet radiation. These secondary metabolites have photoprotective and antioxidant properties. Anabaena/Dolichospermum/Aphanizomenon (ADA) species complex of filamentous diazotrophic cyanobacteria are common components of the phytoplankton blooms. Such bloom-forming cyanobacteria are exposed to UV radiation upon the surface of lakes and water bodies. Here the production of MAAs by members of the ADA species complex is investigated using a combination of structural chemistry and microbial genomics. High-resolution liquid chromatography mass spectrometry (LC-MS) analysis identified the production of the MAA chemical variant porphyra-334 in five of the 36 analyzed Dolichospermum strains isolated from the surface layer of the Gulf of Finland. Surprisingly, the MAA contents of strain Dolichospermum sp. UHCC 0684 was 7.4 mg/g dry weight, a high quantity for cyanobacterial species. Phylogenomic analysis based on 120 bacterial single-copy conserved genes from 101 draft or complete genomes identified 12 ADA species when using average nucleotide identity cutoff values of 96%. The distribution of MAA biosynthetic enzymes was mapped to the phylogenomic tree and suggested that almost half of the species in the complex encode the ability to produce MAAs. MAA biosynthetic enzymes were most prevalent in Dolichospermum and Aphanizomenon strains, with the latter representing 52.8% of the MAA biosynthetic pathways in all 12 ADA species. There has been more than three decades of interest in the use of MAAs as an alternative to commercially used organic UV filters. The quantity of MAAs in Dolichospermum sp. UHCC 0684 is similar to that of red seaweeds already used in sunscreen products. These results indicate bloom-forming cyanobacteria may be a potential source for cosmetic and biotechnological applications of MAAs.