The Effect Of Chimonobambusa Quadrangularis Extract On The Competitiveness Of Microcystis Aeruginosa And Its Mechanisms

Eutrophication,cyanobacteria water blooms and deterioration of water quality resulted by excessive domestic and industrial wastewater and agricultural drainage entering natural water bodies have become a worldwide problem.Researching and developing a more efficient,safe and low-cost method for the treatment of cyanobacteria blooms have been the research hotspots in the field of water ecological environment protection.In recent years,there have been many studies on developing the cyanobacteria inhibitors by using plant extracts,but few studies focused on the effects of plant extracts on the competition between cyanobacteria and other algae species.This study focused on three kinds of algae as the research object:Microcystis aeruginosa,a representative species of cyanobacteria;Scenedesmus obliquus,a representative species of green algae;Nitzschia palea,the representative species of diatoms.From the perspective of maintaining biological diversity and achieving ecological balance,this study investigated the effects of the Chimonobambusa quadrangularis extract(CQE)on the growth of three kinds of algae,and the influence on the competitiveness of M.aeruginosa with the other algae species and its mechanisms.The main conclusions were as follows:(1)Systems of three kinds of algae cultivated separately:When the concentration of CQE was in the range of 0-1.0mg/mL,it had little effect on the growth of the three kinds of algae.However,the 5.0 mg/mL CQE had a significant inhibitory effect on the growth of M.nosa(ANOVA,p<0.01),it had almost no effect on the growth of S.obliquus(ANOVA,p>0.05),and it had a significant promoting effect on the growth of N.palea(ANOVA,p<0.01).(2)A co-culture system of M.aeruginosa and S.obliquus:When concentration of the CQE was 5.0 mg/mL,S.obliquus became the dominant algae specie in the co-culture environment.It indicated that the 5.0 mg/mL CQE can reduce the competitive ability of M.aeruginosa and enable S.obliquus to gain a competitive advantage.(3)A co-culture system of M.aeruginosa and N.palea:When the concentration of the CQE was 5.0 mg/mL,N.palea became the dominant algae specie in the co-culture environment.It indicated that the 5.0 mg/mL CQE can reduce the competitive ability of M.aeruginosa and enable N.palea to gain a competitive advantage.(4)The 5.0 mg/mL CQE significantly depressed the chlorophyll a content of M.aeruginosa,weakened the activity of superoxide dismutase,peroxidase,catalase,and also reduced the malonaldehyde content.It suggested that the CQE impeded the photosynthesis and antioxidant system of M aeruginsa to a certain extent.(5)The M.aeruginosa colony and N.palea were isolated from the water of Taihu Lake,which suffered from severe algal-blooms.The 5.0 mg/mL CQE promoted the growth of N.palea and decomposed the M.aeruginosa colony.It indicated that a given concentration of the CQE had growth inhibitory effect on the growth of M.aeruginosa colony.