Effects Of Sanguinarine On The Physiological Characteristics Of Cylindrospermopsis Raciborskii And Scenedesmus Obliquus And The Competition Between The Two Algae

Previous studies have shown that sanguinarine has strong inhibitory effects on Microcystis aeruginosa(cyanobacterium).As an allelochemical and biogenic algal-inhibiting substance.It is not known whether sanguinarine has selective toxicity against target harmful algae and whether it has an inhibitory effect on other non-harmful algae.Therefore,in this paper,we studied the physiological characteristics of Cylindrospermopsis raciborskii AWT205(C.raciborskii AWT205)and Scenedesmus obliquus FACHB 416(S.obliquus FACHB 416)in the presence of sanguinarine,and investigated the effects of sanguine on the competition between the two algae.In response to sanguinarine stress,the photosynthetic pigment content of two different types of algae,electron transport in the photosynthetic system II,cell viability,the antioxidant enzyme activity,and the oxidation of lipid in the algal cells were investigated.The possible mechanisms of action of sanguinarine on C.raciborskii AWT205 and S.obliquus FACHB 416 were elucidated.The main research results are summarized as follows:Sanguinarine showed a significant inhibitory effect on the growth of C.raciborskii AWT205.But it had no obvious effect on the growth of S.obliquus FACHB 416.When the concentration of sanguinarine reached 80 ?g/L,The cell density of C.raciborskii AWT205 was 21.83%,36.04%,and 39.22% of the control on the 2nd,4th,and 6th days,respectively.Further studies on the toxic mechanism of sanguinarine against C.raciborskii AWT205 and S.obliquus FACHB 416 have been carried out.Sanguinarine caused a slightly decrease in the content of chlorophyll a and carotenoid in the two algae,and slightly decrease in chlorophyll b content in S.obliquus FACHB 416.This transient reduction will be restored.Sanguinine can inhibit the light energy capture ability of C.raciborskii AWT205,causing its electron transfer process to be hindered,and causing the overall performance of its photosynthetic system II to decrease.Sanguineium had a short-term effect on the overall performance of the photosystem II of S.obliquus FACHB 416 at the 4th day of the experiment.Sanguinarine caused a decrease in the cell viability of C.raciborskii AWT205 and S.obliquus FACHB 416 cells.Sanguinine caused oxidative damage to the algal cells of C.raciborskii AWT205 and S.obliquus FACHB 416,and the enzyme activity of the antioxidant system increased.The lipid peroxidation degree of the C.raciborskii AWT205 increased under sanguinarine stress and the degree of membrane lipid peroxidation of the S.obliquus FACHB 416 did not change.Under the stress of sanguinarine,the sensitivity of S.obliquus FACHB 416 in response to sanguinarine stress was lower than that of C.raciborskii AWT205.The co-culture had significant effects on the growth of the populations of C.raciborskii AWT205 and S.obliquus FACHB 416.The growth conditions of C.raciborskii AWT205 and S.obliquus FACHB 416 were all poorer than those of mono-culture.Sanguinarine had an impact effect on the competition between C.raciborskii AWT205 and S.obliquus FACHB 416.With the increase of the sanguinarine concentration,the growth rates of C.raciborskii AWT205 and S.obliquus FACHB 416 are gradually approaching.When the concentration of sanguinarine reached 80 ?g/L,the growth of S.obliquus FACHB 416 was better than that of C.raciborskii AWT205.Under the influence of sanguinarine,S.obliquus FACHB 416 showed advantage in competition.