| Hemolytic activity of Chattonella marina Hong Kong strain(CMHK) in different growth phase and nutrients structure was studied under laboratory conditions. According to the growth curve of CMHK, cells in culture were collected in logarithmic phase, stationary phase and decline phase, respectively, to determine hemolytic activity. Hemolytic activity of CHHK, which was cultured in different nutrients structure, was also determined. Furthermore, acute toxicity test of CMHK on Artemia salina was performed in early logarithmic phase(5 d), late logarithmic phase(13 d), stationary phase(15 d) and decline phase(17 d). The results showed that the highest hemolytic activity was detected in early logarithmic phase. After 5 d culture，the hemolytic activity reached 1.80×10-7 HU/cell, then decreased gradually with culture time increasing. Hemolytic activity of total cells in culture in different growth phase coincided with the growth curve with the maximum reaching 5.32 HU/L in late logarithmic phase. Growth rate of CMHK was greatly depressed by Fe limitation while hemolytic activity per cell was enhanced to 8.37×10-7 HU/cell, nearly 6.5 times higher than that with no Fe limitation(1.33×10-7 HU/cell). Similarly, N, Mn and P limitation could also increase the hemolytic activity of CMHK. Acute toxicity test of CMHK on A. salina showed that the maximum toxicity of the algae appeared at late logarithmic phase. It was found that death rate of A. sinica reached to 77% in 48 h when exposed to the algal culture at late logarithmic phase with algae density being 4.0×104 cells/mL, and.the lowest toxicity on A. sinica appeared in early logarithmic phase with death rate of 20%. |
