UVB Shielding Role of FeCI₃ and Certain Cyanobacterial Pigments

Abstract

Abstract The shielding role of ferric iron (FeCl 3 ) and certain cyanobacterial pigments (a brown‐colored pigment from Scytonema hofmanii culture filtrate and a pink extract from Nostoc spongiaeforme ) against UVB‐induced damage in the filamentous, nitrogen‐fixing cyanobacterium Nostoc muscorum has been demonstrated. Addition of these colored compounds to agarose gels (1–3 mm thick) resulted in a considerable decrease in UVB transmittance through the gels. The lowest UVB transmittance (15%) occurred through a 3 mm gel containing 0.01% FeCl 3 followed by S. hofmanii culture filtrate (40%) and N. spongiaeforme extract (50%). These substances appear to act as very efficient UVB‐absorbing screens. Percent survival and 14 CO 2 uptake of N. muscorum increased significantly if UVB exposure was given on gels containing FeCl 3 or other UVB‐shielding substances. The highest protection of N. muscorum was recorded with FeCl 3 , followed by S. hofmanii culture filtrate and N. spongiaeforme extract. Such UV‐shielding substances if present in required concentration range may enhance the survival of cyanobacteria exposed to high levels of UVB.