Algicidal Activity And Potential Mechanism Of Berberine Sulfate On Microcystis Aeruginosa

Harmful water blooms of cyanobacteria which frequently occur in eutrophic waters is a widespread problem in aquatic ecosystems around the world. Chemical approaches can effectively and rapidly remove harmful algal blooms, however, some algicidal chemicals such as CuSO4and herbicides can cause secondary pollution of aquatic environments, and most of the chemicals are selectively limited which are not safe to non-target organism. Berberine sulfate, the major active constituent of Rhizoma coptidis, exhibits well inhibitory effects on Microcystis aeruginosa. We studied the inhibition effects of berberine sulfate under different environmental factors and the mechanism of berberine sulfate, the results are as follows:1. Algicidal effects of berberine sulfate on Microcystis aeruginosaTo illuminates the effect of berberine sulfate on M. aeruginosa, concentration of berberine sulfate was set to0.625mg/L、1.25mg/L、2.5mg/L、5mg/L、10mg/L、20mg/L、40mg/L and80mg/L. The algal bioassays indicated that the IC50value of berberine sulfate was3.34mg/L. It can be seen that when challenge with berberine sulfate, the inhibition on M. aeruginosa increased with an increasing berberine sulfate concentration. After treated with144h, the inhibition of berberine sulfate on M. aeruginosa were77.83%and85.16%respectively when exposed to10mg/L and80mg/L berberine sulfate. The results indicates that berberine sulfate has a significant inhibitory effect on M. aeruginosa.2. Effect of environmental factors on the activity of berberine sulfate against Microcystis aeruginosaTo understand how environmental factors affect the inhibition of berberine sulfate on M. aeruginosa, the independent effects of some environmental factors, including pH、 temperature、light、water hardness、nitrogen and phosphorus conditions on the growth of M. aeruginosa were investigated. As can be seen from the experimental results, the activity of berberine sulfate decreased with the increasing pH and water hardness value. With the decreases of light intensity, the inhibition of berberine sulfate decreased. Under the condition of high temperature and low temperature, algal inhibiting effect of berberine sulfate obviously enhanced. N and P nutrition have no significant effect on the activity of berberine sulfate on M. aeruginosa. 3. Mechanism of berberine sulfate on Microcystis aeruginosaIn the present study, the intracellular ROS level of M. aeruginosa was significantly increased when treated with80mg/L berberine sulfate over the0.5h exposure period, and decreased with the time of exposure. After2h of exposure at80mg/L berberine sulfate, the results show that berberine sulfate induced part of intracellular H+efflux, enhanced the cell permeability and decreased the photo synthetic efficiency. The cell membrane serious damaged after24h of exposure. In conclusion, the findings reported here suggest that the mechanism of berberine sulfate was involved in the ROS generation in M. aeruginosa, which may induce oxidative damage and cause a decreasing photosynthetic efficiency, cell membrane damage and release of intracellular components, finally lead to cell death.