Inhibitory Effects And Mechanisms Of Straws On The Growth Of Microcystis Aeruginosa

In recent years, with rapid population growth and economic development, more and more waterbody becomes eutrophication due to the irrational development and utilization of water resource. Exploring an effective, economical, no secondary pollution method to control the algae bloom becomes an important task for protecting the water of lakes. Using straw to inhibit the algal is a new way to control algal bloom, which has the features of cost-effective, environmentally friendly, strong ability and no toxic side effects for other aquatic organisms. This article describes the best soaking time, dosage, the inhibition of rice and barley straw under different conditions on the Microcystis aeruginosa and the inhibition mechanism.The inhibitory effects were enhanced by the increasing soaking time; however extensive soaking time was not able to further increase the effect. The inhibition rate reached 75.99% by the rice straw extracts obtained with 15-day soaking time. But 20-day extracts reached 73.15%. Significant inhibitory effect was observed with the dose of the rice straw extracts over 7.5%.The extracts from different parts of rice straw have different inhibitory effect on M.A.. The inhibitory effects of the extracts decrease in the order of rice root, rice head and rice straw. The inhibitory effects of the parts of the rice straw exceed the barley straw except the stalk part. The inhibitory of straw extracts is obvious than the straw, and aerate can strengthen the inhibitory.Sterilization cannot neutralize the inhibitory of the straw or the straw extracts, and the allelochemicals are the dominant factor. Algal cells have a series of stress reaction because of allelochemicals, SOD activity was increased and then decreased, MDA content was gradually increased. From GC/MS detection, the fatty acids and phenolic acids are recognized as the main reason of representing the algal-inhibition.Through the experiment above, we can infer the mechanism of algal-inhibition is: destruct the chlorophyll, cell membrane and influence the activity of some enzymes. Allelochemicals not only hampered the further synthesis of chlorophyll, but also destroyed the chlorophyll originally in the algal cells; allelochemicals caused membrane peroxidation increasing, damaged the cell membrane; membrane peroxidation may produce large amounts of MDA and so on, so MDA content is raised. The decreasing of the activity of SOD breaks the normal balance between the producing and scavenging of intracellular free radical, which leads to excessive producing and accumulation of free radicals, furthermore this can damage the algae to reach the effects of algal-inhibition.