Study on Growth and Toxin Production of Microcystis aeraginosa Strain Under Different Conditions / 环境与健康杂志

ABSTRACT

Objective To study the impact of temperature, light, nitrogen and phosphorus on growth and microcystin-LR production of Microcystis aeraginosa strain under laboratory conditions. Methods M.aeraginosa strain was cultivated in BG-11 medium. Growth was determined by counting cell, while microcystin-LR was analyzed by high-performance liquid chromatography. Results M.aeraginosa strain had a biggest growth rate at temperature of 25 ℃ and light intensity of 3 000 lx, while microcystin-LR production contents reached maximum at 20 ℃ and 5 000 lx respectively. Under the phosphorus-fixed condition, M. aeraginosa amount and mircrocystin-LR content increased by nitrogen concentration and reached the peak when the nitrogen concentration was 650.0 ?mol/L. But higher concentration of nitrogen could probably restrain the cell growth and toxin production. Under the nitrogen-fixed condition, M. aeraginosa strain grew slowly at phosphorus concentration of 1.43 ?mol/L, but had a higher growth rate when phosphorus concentration was 6.50 ?mol/L. No significant change was found with the increase of phosphorus concentration. And almost similar contents of microcystin-LR produced by M. aeraginosa were observed at different phosphorus concentrations. Positive correlations between total microcystin-LR concentrations and chlorophyll-a contents and M. aeraginosa cell densities were found. Conclusion The optimum conditions for growth and toxin production of M. aeraginosa are not the same. Phosphorus is a probable limitation nutrient factor, and a low concentration will satisfy the growth and toxin production of M. aeraginos. The N∶P atomic ratio at 100∶1 was determined as the optimum for growth and toxin production. The total microcystin-LR concentration can be forecasted by M. aeraginosa cell density or chlorophyll-a content.