CADMIUM INDUCED ALTERATIONS IN THE PHOTOCHEMICAL ACTIVITIES OF THE CYANOBACTERIUM, SPIRULINA PLATENSIS (NORDST.) GOM

Experimental evidence shows cadmium induces alterations in photochemical activities at multiple sites. The concentration of cadmium at 0.6 mM is able to cause 55% loss in whole chain as well as 66% in photosystem II catalyzed electron transfer activities in the intact cells of Spirulina. Compared to photosystem II, the activities catalyzed by photosystem 1 are less sensitive to cadmium stress. The measurement of phtosystem II activity at different irradiations indicated light harvesting complex of photosystem I (Phycobilisomes) are targets for Cadmium induced alterations. Thus cadmium exerts multiple effects on the photosynthetic electron transfer in the cyanobacterium, Spirulina platensis and PS II gets inhibited preferentially than PS I.