Study On Inhibitory Effects Of10Common Medicinal Plants On Growth Of Microcystis Aeruginosa

Global eutrophication has been increasingly serious in recent years. As a main result of eutrophucation, harmful algal bloom happens frequently all over the world. Microcysis aeruginosa is one of the dominant species in algal bloom and can release microcystin, which is seriously harmful to the animals and plants living in the same environments. Microcystin of M. aeruginosa is also harmful potentially to human beings. The effects of the water extracts of ten common medicinal plants, including Berberis diaphana, Clematis sp., Picrasma quassioides, Artemisia argyi, Anemone tomentosa, Euphorbia pekinensis, Akebia trifolia, Amygdulus davidana, Salix purpurea and Taraxacum mongolicum on the growth of M. aeruginosa have been evaluated in this paper. Additionally, the inhibiting mechanisms of three potential plants, i.e. B. diaphana, A. davidana, and S. purpurea have been discussed. The main results are summarized as follows:1. When their concentration is above a certain level, the water extract of B. diaphana, P. quassioides and S. purpurea could significantly inhibit the growth of M. aeruginosa. It would significantly reduce the content of chlorophyll a of M. aeruginosa when the concentration of the water extract of B. diaphana and P. quassioides was higher than0.00111g/ml and0.00116g/ml. respectively. However, this inhibition would decrease as the concentration of the water extract of P. quassioides increased. Only when the concentration of the water extract of S. purpurea was0.111g/ml, it showed a strong inhibitory effect on the growth of M. aeruginosa.2. When the water extract of A. argyi. E. pekinensis, A. davidana and T. mongolicum was at low concentration, they could promote the growth of M. aeruginosa. But when at high concentration, they showed strong inhibitory effects on the growth of M. aeruginosa. The water extract of A. argyi showed inhibitory effect only at0.111g/ml. When the concentration of the water extract of E. pekinensis was0.116g/ml, it would significantly reduce the content of chlorophyll a of M. aeruginosa, but it promoted the growth of M. aeruginosa at0.0116g/ml and0.00116g/ml. The growth of M. aeruginosa was inhibited when the concentration of the water extract of A. davidana was equal to or above0.029g/ml, while the concentration of the water extract of T.mongolicum at0.0116g/ml could promote the growth of M. aeruginosa.3. When the water extract of Clematis sp., A. tomentosa and A. trifolia were above a certain level, they could promote the growth of M. aeruginosa. When the concentration of the water extract of Clematis sp. and A. trifolia was equal to or above0.0125g/ml, they both could promote the growth of M. aeruginosa.4. The water extract of A. davidana. B. diaphana and S. purpurea could affect the content of malondialdehyde (MDA) of M. aeruginosa. The content of MDA was significantly reduced when the concentration of water extract of A davidana was at a high concentration after7days of treatment. Low concentration of the water extract of B. diaphana could increase the content of MDA, but the content of MDA reduced in the high concentration of the water extract of B. diaphana; The water extract of S. purpurea did not significantly change the content of MDA at first stage. But the content of MDA of M. aeruginosa significantly increased along with the time.5. The water extract of A. davidana and S. purpurea also influenced the antioxidant enzyme systems of M. aeruginosa. Low concentration of the water extract of A. davidana could increase the activity of SOD of M. aeruginosa, while when the concentration it higher than0.058g/ml could decrease the activity of SOD. When the concentration of the water extract of S. purpurea was0.028g/ml, the activity of SOD of M. aeruginosa also increased first and then decreased in the later stage.6. The water extract of A. davidana, B. diaphana and S. purpurea also influenced the content of protein of M. aeruginosa. The reduction of the protein content of M. aeruginosa was positively correlated with the concentration of the water extract.Based on our experiment, B. diaphana, A. davidana and S. purpurea, show significant inhibiting effects on the growth of M. aeruginosa. Further research on the application of thesethree plants in controlling algal bloom should be carried out.