Abstract
In the present work, impact of UV-B radiation (280-
315nm: 0.4 W m-2) on growth, photosynthetic pigments, protein,
ascorbate, proline and lipid peroxidation have been studied in
two cyanobacteria Nostoc muscorum and Synechocystis PCC
6803. UV-B radiation (2 to 6 hrs) leads to 55% inhibition of
growth in Synechocystis PCC 6803 as comparison to control
where as in Nostoc muscorum growth reduces up to 45%. This
UV-B treatment also significantly decreased the contents of
chlorophyll, carotenoids and phycocyanin. Photosynthetic
pigments decreased with increasing doses of UV-B (2 to 6 hrs)
radiation. However, the inhibitory effect in Synechocystis PCC
6803 was more pronounced than in Nostoc muscorum. With
increasing UV-B exposure period, production of ascorbate (19-
45%), proline (12-29%) and lipid peroxidation was significantly
higher in Synechocystis PCC 6803 as compared to control
sample. It was observed that lipid peroxidation enhanced 33 %
than control sample of Synechocystis PCC 6803. Our result shows
that photosynthetic apparatus is the main target of UV-B
radiation causing degradation of photosynthetic pigments. This
study concluded that Synechocystis PCC 6803 was the susceptible
organism for survival in stress condition than Nostoc muscorum.