The Study On Inhibition Effects Of Microcystis Aeruginosa Growth By Pistia Stratiotes And Its Alkali Extracts

The excessive growth of algae caused by the eutrophication of natural water, isknown as "ecological cancer". Researching a new green methods of low cost as wellas high efficiency, has always been the goal of researchers to pursue. In recent years,people gradually found the advantages of large aquatic plants aboat the restorationto the eutrophication water. With the deepening of the research, the allelopathiceffects of aquatic plants on algae inhibition has surfaced. Research on aquatic plantsallelopathy inhibition of algae in water, and to develop a new type of green reagentsto remove algae, has become a hot spot of algae controlling technology.This paper studied the effect on the concentration of the nutrient and theorganic matter pollution in the water by the growth of Pistia stratiotes, analyzed thenutrient absorption capacity and the pollutant removal ability of the plant, and cameto it can effectively removed the nutrient and organic pollutants in the water.Through Pistia and Microcystis aeruginosa coculture experiments, the paperanalyzed the influence of algal cell density and the concentration of chlorophyll a,as well as that of the concentration of extracellular protein and polysaccharides bythe aquatic plants, found that the plants has significant inhibitory effect on the algalcell proliferation, produces damage to the photosynthesis of algae cells, anddamaged to the integrity of the cell membrane.In addition, this paper also studied the allelopathy of Pistia on Microcystisaeruginosa. cultivation of M aeruginosa by the liquor cultured with P stratiotes, theresult was the liquor effect on algal growth appeared to promotive on lowconcentration and suppression on high. By algal and aquatic plants isolationcultivation experiments, it showed the growth of the plant suppressed effectively onthe algae growth, and when there was algae stimulation, inhibition wouldstrengthen. At the same time,this paper also studied the effect of the aquatic plantsinitial biomass on its algal inhibiting ability. by curve fitting,we calculated out therequired initial biomass of the plant when half inhibition rate. By analyzing changesituation of TN and TP in the coculture water of plant and algae, it indicated theaquatic plants inhibitory effect on algae was not due to nutritional competition, butallelopathy.Finally, using the direct method and indirect method, we extracted alkalineextraction,having obvious inhibitory effect on algae growth,from Pistia stratiotes.Using GC-MS,we found the effective components of inhibition was trans-(2,3-Diphenylcyclopropyl) methyl benzene sulfoxide and9-(2’,2’-Dimethylphenylhydrazono)-3,6-dichloro-2,7-bis-[2-(diethylamine) ethoxy] fluorene. In addition to P stratiotes, we selected Polygonum hydropipe, Trapa japonica, Acorus calamusand Phragmites australis,4species of aquatic plants, and worked inhibitingexperiments of their alkaline extract on algal. By GC-MS analysis of theirextracts, it was found active ingredients to algae inhibition was not single, but theresult of the various chemical material mixing action.