Mycosporine-like amino acids profile and their activity under PAR and UVR in a hot-spring cyanobacterium Scytonema sp. HKAR-3

The cyanobacterium Scytonema sp. HKAR-3 isolated from a hot spring in India was investigated for the presence of mycosporine-like amino acids (MAAs) and their induction under PAR and PAR+UVR. High-performance liquid-chromatograph (HPLC) analysis revealed the presence of two MAAs, mycosporine–glycine (?max = 310 nm) and an unknown MAA-334 (?max = 334 nm), with retention times of 4.1 and 8.7 min, respectively. This is the first report for the presence of two MAAs and, in particular, the synthesis of mycosporine–glycine in any strain of Scytonema. There was no effect of radiation type (PAR or PAR+UVR) on the synthesis of mycosporine–glycine; however, the synthesis of MAA-334 was found to be higher in samples receiving PAR+UVR than in those receiving PAR only. There was a circadian induction in the synthesis of MAAs under alternate 12-h light (PAR or PAR+UVR) and dark periods. MAAs were found to be induced mostly during the light period and their production dropped again during the dark period. This suggests that the synthesis of MAAs is an energy-dependent process and depends on solar energy for its maintenance in natural habitats.