Mechanism Of Cd(?) On Colony Formation Of The Microcystis Aeruginosa

Microcystis Aeruginosa 905 is used as test object in this experiment.The cadmium in a certain concentration of cadmium chloride solution is added to culture liquid to study the role of cadmium on Microcystis aeruginosa group formation mechanism.It helps to clarify the effect of cadmium on the formation of cyanobacteria bloom and Microcystis bloom outbreak mechanism.It has very important significance.This test research cadmium ion adsorption characteristics about 905 and study the impact of cadmium ions on 905 cell growth and colony formation,then studying the effect about different doses of cadmium ions on polysaccharide content and plastic sheath polysaccharide monosaccharide component to elucidate the mechanism of cadmium ions on 905 colony formation.It provide scientific and effective governance accurate reference data for bloom warning(producing blooms boundary values),While providing scientific biography for Heavy Metal pollution prevention and blooms control provide a scientific basis.Microcystis aeruginosa experimental groups of seven different cadmium ion concentrations were set up,and the test period was 10 days.During the test,the concentration of cadmium ions in Microcystis aeruginosa experimental groups respectively were Omg/L,0.0125mg/L and 0.025 mg/L,0.05 mg/L,0.1 mg/L,0.2 mg/L,0.4 mg/L.The experiment Study effects of cadmium about the growth and groups of 905 cells and study cadmium ions adsorption characteristics and the impact of these three areas of 905 polysaccharide content and biochemical features.Experiment study the mechanism by the effect of cadmium aboout 905 colony formation.The experiment on effect of Cd2+ on the number of Microcystis aeriginosa cell density and colony showed:Compared to the control group,in the concentrations of Cd(?)(0.0125,0.025 mg/L),905 cell density was significantly increased.In the the concentrations of Cd(?)(0.05,0.1,0.2 and 0.4 mg/L),Microcystis aeruginosa cell density was gradually reduced.At the same time,Three concentrations of Cd(?)(0.05,0.1 and 0.2 mg/L)significantly induced formation of small Microcystis colonies(p<0.05)compared with the control group.To study the absorption and adsorption characteristics of Cd(?)by intracellular polysaccharide(IPS)and bound extracellular polysaccharide(bEPS)in Microcystis aeruginosa cell.There was a linear relationship between the amount of Cd(?)adsorbed by algal cells and the amount added to cultures in the rapid adsorption process that occurred during the first 5min of exposure.M aeruginosa adsorbed nearly 80%of 0.2 mg/L added Cd(?),while>93%of Cd(?)was adsorbed in the groups with lower added concentrations of Cd(?).More than 80%of the adsorbed Cd(?)was adsorbed by bEPS.During the experiment,cells were extracted from the samples,and the polysaccharide in the cells was extracted.Compared with the control group,the study found that the lower concentrations of Cd(?)(0.0125 and 0.025 mg/L)had no significantly effect on the formation of the polysaccharide.Three concentrations of Cd(?)(0.05,0.1 and 0.2 mg/L)significantly increased the intracellular polysaccharide(IPS)and bound extracellular polysaccharide(bEPS)contents of M.aeruginosa(p<0.05).In the experiment,the bound extracellular polysaccharide(bEPS)was separated into two components by dextran column chromatography.It was named p1 and p2,through the standard curve,the molecular weight of p1 and P2 was 2.72×105,2.6×105,respectively.The study found that different concentrations of cadmium on glucuronic acid content of bound extracellular polysaccharide have the different effects,the concentration of 0.025 mg/L treated glucuronic acid presents a significant growth in Bound extracellular polysaccharide,its' ratio reached 70%.At the same concentration(0.05 mg/L),during the first six days,the glucuronic acid content have significant growth,and gradually decreases with time increases.Different concentrations of Cd2+ have an impact on Microcystis aeruginosa 905 monosaccharide component types.In addition to under the effect of 0.05mg/L Cd2+ monosaccharide containing arabinose and 0.1 and 0.2 mg/L Cd2+ monosaccharide containing guluronic acid,in the tenth day,the concentration of each treatment group includ monosaccharide composition of polysaccharide mannose,glucosamine,rhamnose,galactosamine,glucose,galactose,xylose and fucose,but the proportion of each monosaccharide component is different for different concentrations of Cd2' response;At the same concentration of Cd2+(0.05 mg/L),each monosaccharide component types and proportions in Microcystis polysaccharide change significantly over time,including glucosamine,rhamnose,arabinose and other monosaccharides species ratio changes are obvious.