The possibility of using Cyanobacteria Synechocystis sp. for the assessment of the degree of water pollution with heavy metal salts

For the first time there are provided data on the toxicity of salts of heavy metals to the cyanobacteria Synechocystis sp. CALU 713 and PCC 6803. Changes of light and temperature conditions were shown to modify cyanobacteria sensitivity to the toxic effect of salts of heavy metals. The toxicity of salts of heavy metals is determined by the dose-dependent effect of the reducing the growth rate of cyanobacteria in the incubation medium on water basis. Changes of light and temperature culture conditions modify the sensitivity of the cyanobacteria Synechocystis sp. to toxic effect of salts of heavy metals. The decrease in temperature and light in various degrees enhances the toxic effect of salts of heavy metals. Morphological changes of cyanobacteria, caused by the toxic action of salts of heavy metals were established to be nonspecific, regardless of the strain and species of the studied toxicant, showing the change of shapes and sizes, including dividing cells. At the ultrastructural level morphological changes in the cells of cyanobacteria are represented by changes of the thickness and the integrity of peptidoglycan layer of the cell wall; the damage to intracellular organelles relevant to energy metabolism: divergent tilakoid membranes with formation of intratilakoid spaces; agglutination of phycobilisomes and accumulation of polyphosphate granules; fibrous transformation of nucleoplasms with the loss of the typical granulation. A strain of Synechocystis sp. CALU 713 is the most sensitive to the toxic action of salts of heavy metals and, therefore, suitable for the use in experimental toxicology. Cyanobacteria Synechocystis sp. CALU 713 and PCC 6803 are promising test-object in experimental toxicology for the assessment of the degree of water pollution with heavy metal salts. There were obtained parameters of toxicity of heavy metal salts (AgNO₃; 3CdSO₄•8H₂O; Hg(CH₃COO)₂; CuSO₄•5H₂O) for two strains of the cyanobacteria Synechocystis sp. In these circumstances there were revealed morphological changes of the surface ultrastructure of cells of Synechocystis sp.