Abstract
The aim of this study is to determine the effect of salinization and wastewater stresses on the growth and some cellular contents of the unicellular cyanobacterium Synechococcus elongatus (strain PCC 7942). The results indicated that the treatment of S. elongatus with NaCl to 400 mgL−1 was significantly increased the growth of this cyanobacterium and its cellular macro-molecules. However, with increasing concentration, the effect becomes inhibitory to cellular growth and cell contents. Also, in this study, the cells of S. elongatus were exposed to the lethal concentration (800 mg L−1) to study the extent of the sensitive or resistance effects of the organism to salinity stress. In this respect, treatment with NaCl at the lethal concentration (800 mg L−1) had different effects on its detected amino acids. Whereas, all amino acids exhibited stimulatory responses, except Gly., Ala., leu., and His., which significantly inhibited. On the other hand, the internal cellular structure, which was examined with TEM, showed a partial dissolution of cell wall and most cell components could be observed although not as clear as in control cell. Meanwhile, salinization treatment induced partial disorganization of the cell end contents. Although, the treatment with wastewater induce the growth and stimulate the cellular contents of S. elongatus, the cells exhibited an elevation in starch granules and disorganization of thylakoid membranes.