Effect of NaCl salinity on the growth, metabolites, and antioxidant system of Microcystis aeruginosa

Abstract

The physiological and biochemical adaptations of the cyanobacterium Microcystis aeruginosa, grown in a saline environment, were estimated. M11 cultures were exposed to variable salt concentrations (0.5, 1.0, 2.0, and 4.0 g NaCl L−1). The cell density and chlorophyll contents decreased with increasing salinity. The carbohydrate and protein contents were enhanced under lower salinities. The data demonstrated that M. aeruginosa could endure an osmotic potential of 4.0 g NaCl L−1, whereas growth was inhibited under hypersaline conditions above 2.0 g NaCl L−1. The antioxidant activities were evaluated, with salt stress exacerbating membrane lipid peroxidation as indicated by an increasing malondialdehyde (MDA) content. Obvious alterations in the antioxidant enzymes were diverse between the hypo and hypersalinities. Under the hyposaline treatments, high contents of superoxide dismutase (SOD) and catalase (CAT) were detected, whereas hypersaline treatments induced a decrease compared to the control. Accordingly, salinity might be a controlling factor inhibiting cyanobacterial blooms in saline lakes of the Mongolia–Xinjiang plateau, China.