Effect of UV radiation on the synthesis of UV-absorbing Compounds in eleven cyanobacteria acclimated to different salinities

Abstract

High-Altitude Andean Lakes HAAL serves as idealenvironments to study the cyanobacterial diversity of a terrestrial,hypersaline system that has a potential value for the bioprospecting [1]. In thiswork, we performed isolation of novel cyanobacteria from diverse lakes andsamples from the HAAL. In addition, effects of threedoses (15, 30 and 60 Wm−2) of UV radiation on the synthesis ofUV-absorbing compounds in the isolated cyanobacteria acclimated to foursalinities (i.e., 0, 10, 30 and 60 psu) were investigated.We isolated representative strains from eleven genera (Anabaena, Nostoc, Symplocastrum,Leptolyngbya, Phormidium, Synechococcus, Pseudoanabaena, Nodularia,Synechocystis, Chroococcus and Cyanosarcina). Increase of salinity (i.e.,to 0 from 60 psu) affects the growth rate of cultures. Combined effect of bothsalinity and UV radiation resulted in lower biomass. Subsequent acclimationfrom short period (less than 6 h) of UV radiation to subsequent duration oftreatment (more than 6 h) resulted in an increase of Chl-a content.The production of UV-absorbing compounds such asscytonemin and mycosporine-like amino acids (MAAs) were studied. At an intermediatesalinity (i.e., 10 psu) and after 3 h of exposure to UV we observed the greatestaccumulation of UV-absorbing compounds. The detected UV-absorbingcompounds may play a dual role as passive sunscreens and as osmotic protectant,providing efficient tolerance mechanisms to original hardconditions impairing on the HAAL.