Microcystis Bloom Microbial Control

The Microcystis water-bloom controlling by algae-lysing bacteria and algae-eating flagellates were preliminarily studied in this paper.8 strains of algae-lysing bacteria were seperated from field water samples. Afer further screening, we found strain 5 was the best of them. Strain 5 could kill Microcystis cells by secreting metabolic products. The physilogical and biochemical identification suggested that strain 5 was Pseudomonas stutzeri. Algae-lysing bacteria would be one of controlling methods for microcystis water-bloom.The enumeration of protozoan and determination of chlorophyll a of different water samples suggested that the more flourishing cyanobacteria was, the larger population of protozoan there was. So there might be relations between the population of cyanobacteria and the population of protozoan. A algae-eating flagellate was seperated from a pond with water bloom. Its morphological characters were observed under optical microscope, confocal scanning light microscope, scanning electron microscope, transmission electron microscope. To get large population, the culturing of the flagellate was studied. Synechocystis, Microcystis, Anabaena, Chlorella, E. coli, yeast cells and yolk, milk powder were used as feed, respectively. Results showed that Synechocystis, Microcystis, milk power, yolk and yeast were its favorite foods. Among them, Synechocystis and yeast cells were better than others. Storing at 4°C for a month, it could survive and reproduce as usual. It was cheap for us to culture and rapidly reproduce the flagellate.The Cytophagocytesis of the flagellate to several micro-algae were compared in this paper. The single cellular blue algae (Microcystis and Synecocystis) could be effectively grazed by the flagellates, but it had no influence on filamentous blue algae and single cellular green algae; And we studied on the grazing on Microcystis by the flagellates underdifferent culture conditions. Conclusion: ventilization and stirring promote grazing; The optimum temperature of grazing was 30°C ; There was no obvious difference of the flagellates' grazing ability between pH 5 to pH 8. When flagellates/algae was about 1/200 the flagellates could clear up almost all of algal cells within 36h. The relative ability of protease in flagellates greatly increased after grazing on Microcystis. But the cytophagy could not decrease the amount of microcystin. The cytophagy was promoted by low concentration phenol and was inhibited by low concentration phenol. The flagellate still had the ability of eating Microcystis at higher concentration of NH/-N. The amount of Chi a of field water samples decreased when added the flagellate into it.With more studies,the flagellates might be applied to control the populations of Microcystis and other single cellular blue algae in environment.