Ultrastructural changes induced by selected cadmium and copper concentrations in the cyanobacterium Phormidium: interaction with salinity

The effects of two heavy metals, copper and cadmium, were studied in the presence of different salinity on the growth and ultrastructure of cyanobacterium Phormidium Ol 75. Both toxic metal ions Cu2+ and Cd2+ inhibited growth and caused marked changes in the ultrastructure of the tested cyanobacterium. The main alterations induced by copper and cadmium included the development of large areas of intrathylakoidal space, the disorganisation and degradation of thylakoid membranes, and at higher metal concentrations, the lysis and distortion of affected cells. Furthermore, in cells treated with copper, an increased number and size of cyanophycin granules was documented. The analysis of chlorophyll a content, and the observation of ultrastructures for cells exposed to elevated copper concentration did not show any detoxyficating effect of salinity. With the increased salinity, cells treated with cadmium, showed a reduction in the effects of metallic toxicity.