Adsorption Of Copper,chromium And Uranylions By Deinococcus Radiodurans And Construction Of Genetic Engineering Vector

Background: People pay close attention to the problem of environmental pollution,heavy metal pollution caused by the production and development of industry seriously endangers the health of human beings and destroys the ecological environment.At present,the treatment of heavy metals in the environment is mainly physical and chemical methods,but these methods are not the best methods to deal with heavy metal pollution.The biological treatment methods has emerged in recent years.It is to remove the heavy metal pollutants by using the method of adsorption or reduction of microorganism itself.Deinococcus radiodurans is known as an extremely resistant microorganism on the earth.It is highly resistant to ionizing radiation.It has great prospects for bioremediation of radioactive and heavy metal pollutants.Sulfate reducing bacteria(SRB)is a kind of bacteria with strong reduction.It can reduce some high priced heavy metals such as six valent chromium and uranyl ions to a low price state,so as to reduce their environmental toxicity.Objectives: The purpose of this study is to explore the adsorption of copper and chromium by Deinococcus radiodurans,and to explore the dsorption of uranium by Deinococcus radiodurans in the condition of simulating uranium waste water.Using the super strong radiation resistance of Deinococcus radiodurans and the strong reducibility of the sulfate reducing bacteria.The gene Dsr A of sulfate reducing bacteria was transferred into Deinococcus radiodurans.It is expected to be a genetically engineered strain with super strong radiation resistance and strong reduction effect.In order to be able to deal with uranium in the solution of uranium waste water.The high valence uranium ions was adsorbed and reduced to low valence insoluble tetravalent uranium.The purification treatment of uranium waste water can be achieved to reduce the harm to the environment.Methods: In this experiment,the factors affecting the adsorption of heavy metal copper ions and chromium ions and radioactive heavy metal uranium by Deinococcus radiodurans were investigated.The adsorption of metal ions by Deinococcus radiodurans was explored for different time,concentration of different ions and concentration of different bacteria.Analysis of the changes of functional groups before and after the adsorption of these metal ions by an infrared spectrometer.The surface changes of the adsorption of these heavy metal ions by bacteria were observed by electron scanning electron microscopy(SEM).The vector p RADK-Dsr A containing Dsr A gene of SRB was constructed,and the constructed vector was transferred into Deinococcus radiodurans by using he competent cell method,so as to enhance the reduction function of the Deinococcus radiodurans.To explore whether the new genetic engineering bacteria can enhance the adsorption or reduction of heavy metal ions,especially uranyl ions.Results: Infrared spectrometer shows the change of active functional groups such as amino acids,hydroxyl groups and carboxyl groups before and after adsorption on Cu2+,Cr6+ and uranium,and confirms that Cu2+,Cr6+and uranium has been adsorbed.The absorption peaks of Cu2+ and Cr6+ adsorbed by bacteria are found by the energy spectrum analysis.Electron scanning electron microscopy(SEM)found the changes in the surface of the two bacteria before and after the adsorption of Cu2+ and Cr6+.It showed that they adsorbed metal ions,and the adsorption effect of Cu2+ was better than that of Cr6+.The coexistence of F-and NO3-has a certain adsorption effect on uranium,and the best adsorption concentration is 6mg/L.The best adsorption conditions for Cu2+ and Cr6+ were: under the condition of 30 p H and 7 p H,the best adsorption time was 80 min,the best adsorption concentration for Cu2+was 0.08 mol/L,and the best adsorption concentration for Cr6+ was 0.0138mol/L.With the increase of bacterial concentration,the adsorption capacity of Cu2+ and Cr6+ was also increased.The vector p RADK-Dsr A containing the Dsr A gene was constructed successfully.Conclusion:The radiation resistant coccus has a certain adsorption effect n heavy metal copper ions,chromium ions and radioactive heavy metal uranium.Under the simulated uranium wastewater environment,that is,a certain concentration of F-and NO3-coexist,it will not affect the growth activity of the Deinococcus radiodurans.The p RADK-Dsr A was successfully constructed.