Physiological responses to Cd~(2+) stress in Spirulina platensis

Under Cd2+ stress,some physiological properties were changed in Spirulina platensis.Results showed that,between 0 to 24 mg/L CdCl2,soluble protein contents were all below the control,and the antioxidant systems were affected,too.Superoxide dismutase(SOD) and peroxidase(POD) were both induced in high level,moreover,the activities increased at first,and then decreased.The activity of ascorbate peroxidase(APX) increased when Cd2+ concentration increased,however,all of APX were below the control.Meanwhile,the activities of catalase(CAT) were all above the control,and increased along with Cd2+ concentration increasing.The activities of glutathione peroxidase(GSH-PX) were all below the control,and the least decreased to 25%.The remarkable enhancement of malonyl dialdehyde(MDA) appeared to be an obvious physiological response due to Cd2+ treatment.There was a close positive correlation between MDA content and Cd2+ concentration.