Cadmium induced oxidative stress in Dunaliella salina

Abstract

The unicellular green algae Dunaliella salina contains various antioxidants which protect the cell from oxidative damage due to environmental stresses such as heavy metal stress. In the present study, the response of D. salina at the stationary growth phase to oxidative stress generated by cadmium chloride was investigated. Growth, expressed as cell number per ml of culture, did not change up to 75 μM cadmium but decreased significantly at 100 and 150 μM Cd²⁺. Reduction in chlorophyll content and carotenoids content per ml of culture was observed in the presence of Cd²⁺. Total antioxidant activity, expressed as μmole Trolox equivalent per 106 cell (μmol TE 10⁶ cell^-1) and also total phenolic content (pg GAE, cell^-1) were significantly reduced in the presence of Cd²⁺. Lower Cd²⁺ concentration had no influence on the activity of ascorbate peroxidase, 100 and 150 μM Cd²⁺ caused significant reduction in enzyme activity. Lipid peroxidation, reported as malondialdehyde content, was the same as control up to 100 μM Cd²⁺ but increased at higher Cd²⁺ concentration. It is concluded that high concentration of cadmium have negative effect on aquatic algae.

Keywords: Dunaliella salina, Carotenoids, Antioxidant activity, Cadmium chloride, Lipid
peroxidation, Ascorbate peroxidase