Abstract：Culture experiments were carried out about the effects of Cd2+ stress on the growth of Skeletonema costatum, in the meanwhile, the activity of dismutase (SOD), diamine oxidase (DAO), polyamine oxidase (PAO), and the contents of malondialdehyde (MDA) and various forms of polyamines extracted from algae cells were monitored. It aimed to explore the response and physiological roles of polyamines to the heavy metal stress in microalgae. The results showed that Cd2+ inhibited the growth of Skeletonema costatum, and the greater the concentration was, the stronger the inhibition would be. With the enhancement of Cd2+ stress, MDA content in the Skeletonema costatum cell increased slightly, SOD activity reduced significantly and DAO, PAO activity enhanced respectively. As the effect of Cd2+ stress strengthen, the contents of free putrescine (Put), spermidine (Spd) and spermine (Spm) decreased firstly and increased subsequently; conjugated Put, Spd and Spm contents increased at first and then decreased. However, bound Put, Spm and Spd as well as total Put and total Spm kept increasing. It suggested that Cd2+ stress caused oxidative damage to Skeletonema costatum cells. Meanwhile, the enhancement of DAO and PAO activity as well as the increasement of free Put, bound Spd and Spm, total Put and total Spm would enhance the resistance ability of Skeletonema costatum to Cd2+ stress.
