EFFECTS OF NITROGEN NUTRIENT ON THE PRODUCTION OF MYCOSPORINE-LIKE AMINO ACIDS IN NOSTOC SPECIES

Mycosporine-like amino acids MAAs belong to a family of secondary metabolites produced by a wide range of different organisms. These compounds had several potential applications in biomedical, in cosmetics and toiletries. In the present study, three Nostoc strains distributed in soil and freshwater were tested for MAA production under different nitrogen conditions. UV-B radiation significantly enhanced the production of MAAs in Nostoc linckia, Nostoc muscorum and Nostoc paludosum under nitrogen sufficient and deficient conditions. The contents of MAAs significantly increased in these three Nostoc strains with prolonged UV-B treatment under both nitrogen conditions. Both UV-B exposed N. muscorum and N. paludosum produced much less MAAs under nitrogen deficiency in comparison to culture under nitrogen sufficiency, respectively. There was just little difference of MAA contents in UV-B treated N. linckia when it was cultured under both nitrogen conditions. After separation by HPLC and characterization by in-line absorption spectra and mass spectra, one type of MAA porphyra was induced by UV-B in N. linckia under nitrogen sufficient and deficient conditions, and N. muscorum synthesized another kind of MAA shinorine under nitrogen sufficient and deficient conditions. However, UV-B induced N. paludosum to produce porphyra under nitrogen sufficient condition but shinorine under nitrogen deficient condition. These results indicated the nutrient nitrogen levels could regulate the types and amounts of MAAs in Nostoc species. These strains would be a better source for the industrial production of MAAs that can be used as organisms for studying the biosynthetic route of MAAs in nitrogen conditions.