Study On The Synergetic Effect Of Removing Cr(?) From Water By The Combined Of Leersia Hexandra Swartz-Bacillus Cereus

Waters polluted by chromium pose a great threat to the ecological environment and human health,which thus makes it urgent to govern chromium pollution.With a number of disadvantages,traditional remediation methods(like physical and chemical methods)are very likely to cause secondary environmental pollution especially in the presence of light chromium pollution.In recent years,research on the technique of plant-microbe combined remediation has drawn the great attention of scholars.As the only hyperaccumulator in chromium reported and discovered in China,Leersia hexandra Swartz has great potential in the remediation of heavy metal chromium pollution.From the rhizosphere of Leersia hexandra Swartz,the research group found a high abundance of chrome-resistant bacillus which was identified as Bacillus cereus.This paper studied the ability of the synergistic system of Leersia hexandra Swartz and Bacillus cereus in purifying chromium pollution and the possibility of Leersia hexandra Swartz resistant to Cr by Bacillus cereus to provide theoretical reference for the remediation of chromium pollution by combined Leersia hexandra Swartz and Bacillus cereus.The results are as follows:1.Under different initial concentrations(5,10 and 20 mg/L)of Cr(VI),Leersia hexandra Swartz was inoculated with different concentrations of Bacillus cereus to discuss its reduction of Cr(VI)in waters and determine the optimal inoculation concentration under different concentrations of Cr(VI).When Leersia hexandra Swartz was inoculated with the optimal concentration of Bacillus cereus,the reduction rate of Cr(VI)in waters by the synergistic system of Leersia hexandra Swartz and Bacillus cereus exceeded 95%,far higher than that of a single system,indicating the strong ability of the synergistic system in purifying chromium pollution.2.Hydroponic experiments were conducted to explore the physiological response of Leersia hexandra Swartz inoculated with the optimal dose of Bacillus cereus to the stress of Cr(VI)resistance under different initial concentrations(5,10 and 20 mg/L)of Cr(VI).Leersia hexandra Swartz inoculated with microbes grew significantly better than the control group,saw a continuous increase in root length and biomass,and showed significant differences under the medium and high concentrations of Cr(VI)compared with the control group.In addition,the leaves of Leersia hexandra Swartz inoculated with microbes had significantly higher CAT and APX activities,soluble protein,metallothionein and phytocomplexins than the control group,indicating that Bacillus cereus increased the physiological response of Leersia hexandra Swartz resistant to Cr and reduced the damage of Cr to Leersia hexandra Swartz.3.Hydroponic experiments were conducted to analyze the chemical morphology and enrichment amount of chromium in Leersia hexandra Swartz under different initial concentrations(5,10 and 20 mg/L)of Cr(VI)and determine the effect of the inoculation of the optimal concentration dose of Bacillus cereus on the chromium enrichment ability of Leersia hexandra Swartz.The experimental results showed that: The chemical form of chromium in Leersia hexandra Swartz was mainly dominated by residue,followed by hydrochloric acid extraction state and then ethanol extraction state.The chemical morphology and content of chromium in Leersia hexandra Swartz inoculated with microbes were higher than those of the control group.In addition,the content of chromium in Leersia hexandra Swartz after enrichment demonstrated: Root > stem > leave.