The Effects Of Physical And Chemical Agents On The Secretion And Hemolysis Of Anabaena Va-Kiabilis Hemolysin

The blue-green algae is one of the main species responsible for blooms and red tide which distribute in freshwater and sea area .Mass growth of cyanobacteria can secrete large amounts of hemolysin, then cause the deterioration of water quality, endanger aquicolous organism and human health, decrease the output of fish and seashell and do great harm to aquaculture. Thus, by the support of National Natural Science Fund, through culturing the Anabaena Va-Kiabilis OL S1, Synechococcus PCC 7310 and Synechococcus PCC 7003, We found that the cell suspension of A.Va-Kiabilis could secrete hemolysin, which could cause hemolysis of New Zealand rabbit erythrocyte after the suspension was centrifugated and concentrated. But the cell suspensions of S. PCC 7310 and S. PCC 7003 had slightly hemolytic activity to New Zealand rabbit erythrocyte. The A. Va-Kiabilis hemolysin is one of the secretion substances outside the algae cells. Gradual increase in hemolytic activity in the medium was observed during the later logarithmic growth phase, and relatively high hemolytic activity was sustained in a long time,but we haven't found any hemolysis activity in the stagnant and the former logarithmic growth phase.We found that there was a relationship between the A. Va-Kiabilis grown condition and the hemolysin secretion. A. Va-Kiabilis can secrete more hemolysin at 24~35℃, and the optimal temperature is at 28~30℃. More hemolysin can be secreted at pH in the range of 7~9. When pH less than 7 or more than 9, the hemolysin secretions of A. Va-Kiabilis are restrained obviously. In the normal light desity condition, the A. Va-Kiabilis can grow rapidly and secrete more hemolysin with an increase in light density, but it does not have significant effects on the secretion of hemolysin. When added 10~20ug/mL glycerol to the supernatant fluid, we found glycerol could increase the grown rate and toxin synthesis in A. Va-Kiabilis, butchloromycetin had no obvious effect on the toxin synthesis. Glycerol was one of the prosomas to form the lipid. The addition of little glycerol could accelerate A. Va-Kiabilis secrete more hemolysin. So it was supposed that this kind of the hemolysin might be similar to lipid, but not protein.Among the various animals tested, rabbit erythrocyte was highly sensitive to the hemolysin secreted by A. Va-Kiabilis, human and mouse erythrocytes were less sensitive than rabbit erythrocyte, but gold fish and cat erythrocytes were insensitive. The hemolytic activity of concentrated supernatant fluid of A. Va-Kiabilis was temperature dependent, and hemolysis became more rapidly with an increase in temperature, but at 0"C, the supernatant fluid could not cause hemolysis. There was a short lag time before initiation of hemolysis. The lag time became longer with decreasing temperature. Hemolytic activity was enhanced with the decrease in pH. The maximum hemolytic activity occurred at pH 5.0, and even was similar to the positive comparison. Hemolytic activity was also enhanced by Mg2+> Fe3\ Ca2+, but inhibited by Cu2+ > Mn2+, and was not effected by Ge2+ Zn2+. When we added a little cholesterol, sphingomyelin and lecithin to the concentrated supernatant, the hemolytic activity decreased. It was possible that these lipid compounds competed with the hemolysin for the target sites on the erythrocyte membrane, which could combine with the particular part on the surface of erythrocytes membrane. Thus, it was supposed that the hemolysis action might be related with the competitive combination of the target sites on the erythrocyte membrane.