Salinization and wastewater effects on the growth and some cell contents of Scenedesmus bijugatus

The aim of this study is to determine the effect of salinization and wastewater stresses on the growth, some cellular contents (total soluble proteins, total soluble carbohydrates, nucleic acids, and amino acids composition) and ultrastructure using TEM of unicellular green alga Scenedesmus bijugatus. Treatment of S. bijugatus by NaCl at 10 and 50 mg L⁻¹ significantly increased the growth of this alga and its cellular macro-molecules. While, treatment above this concentration with NaCl significantly inhibited the growth and cellular macro-molecules. On the other hand, treatment by NaCl at the pre-lethal concentration (300 mg L⁻¹) had different effects on its detected amino acids. Whereas, Asp. Acid, Pro, Cys, Val, Iso-leu, leu, Phe.ala and Lys were slightly stimulated with salinization treatment. On contrast the levels of amino acids: Thr, Ser, Glu.acid, Gly, Ala, Mth, His and Arg were markedly inhibited. Ultrastructure examination of treated S. bijugatus by 300 mg L⁻¹ of NaCl for 8 days showed increase of starch granules, shrinkage of cell contents and thickening of cell wall. The recorded data indicated also that treatment by wastewater with all concentrations led to stimulatory effects on their growth and cellular macro-molecules except at 100% wastewater which had inhibitory effects on Asp., Gly., Thr., Ser., Pro., Glu., Ala., Meth., and Cyst., of S. bijugatus. Also, wastewater induced a slight change in the treated S. bijugatus as elevation in starch granules and presence of thylakoid membranes although not clear as in the control.