Investigating the effect of salinity and UV stress on the biochemical properties of Scenedesmus obliquus algae

Abstract Scenedesmus obliquus is a unique eukaryotic microorganism that has a high range of tolerance against environmental fluctuations including salinity and UV radiation. The purpose of this study was to investigate the coping method of Scenedesmus obliquus algae cells against salinity stress and ultraviolet rays. The experiments were performed under different salinity treatments of 0 mM, 150 mM , 250 mM , 350 mM NaCl, 450 mM NaCl, 150mM NaCl+UV, 250mM NaCl+UV, 350mM NaCl+UV, 450mM NaCl+UV and UV. The effect of salinity and ultraviolet radiation on survival ability, growth rate, total protein content, photosynthetic pigment content, total sugar content, soluble sugars, insoluble sugars, hydrogen peroxide content, malondialdehyde content, activity of antioxidant enzymes including catalase, peroxidase, ascorbate peroxidase and polyphenol oxidase were investigated. In high concentrations of sodium chloride along with UV stress, cell growth rate, total protein content, photosynthetic pigments, content of insoluble sugar, peroxidase enzyme activity and polyphenol oxidase enzyme activity decreased. The content of soluble sugars, catalase enzyme activity and ascorbate peroxidase enzyme activity increased along with the content of hydrogen peroxide and malondialdehyde. According to the findings of this research, it can be said that ultraviolet rays combined with high salinity reduce the growth of Scenedesmus obliquus algae. The increase in soluble sugar content is caused by the activity of catalase and ascorbate peroxidase enzymes to deal with oxidative damage to cells. Also, the reduction of photosynthetic pigmentand and other indicators show the low resistance and lack of adaptation of this type of algae to the intensity of ultraviolet rays and high salinity.