Abstract:The effects of temperature, pH and different divalent cations on the hemolysis induced by Karenia mikimotoi Hasen were studied, and the hemolytic properties were analyzed. The results showed that the hemolytic activity of K. mikimotoi was 64.69±6.43 HU L-1 and 6.17±0.61×10-6 HU cell-1. The hemolytic activity increased with the temperature enhanced at 0°C~37°C. pH had an obvious effect on the haemolytic activity, and there was the highest activity at pH 6.0. When the concentration was 5 mmol/L, the divalent cations such as Cu2+, Mg2+, Mn2+, Ca2+, Co2+, Zn2+ and Hg2+ had different inhibition on the hemolysis, which Hg2+ was the strongest inhibitor. High concentration of Hg2+ induced a rapid and cooperative cell aggregation, and then prevent penetration of Hg2+ into the cells, which did not only avoid any haemolysis induced by the Hg2+ entrance, but also inhibited the destruction by the hemolytic toxin. However, this phenomenon could be eliminated by EDTA.