Reduction Effect And Mechanism Of Uranyl Ion By DsrA Gene-transformed Deinococcus Radiodurans

Objective: To investigate whether the dsrA gene in sulfate-reducing bacteria can enhance the reducing ability of Deinococcus radiodurans and improve its enrichment ability of uranium.And explore the oxidative stress ability of Deinococcus radiodurans.It provides a theoretical basis for the study of biological treatment of uranium-containing wastewater.Methods:1.The competent cells of Deinococcus radiodurans were prepared.The recombinant vector p RADK-dsrA was transferred into Deinococcus radiodurans to obtain radiation-resistant genetically engineered bacteria.Double enzyme digestion identification,PCR identification,single flux sequencing technology and real-time fluorescence quantitative PCR technology were applied to identify the reduction gene dsrA in E.coli DH5?,after which the recombinant vector p RADK-dsrA was extracted and transferred into Deinococcus radiodurans by chemical transformation method to construct the radiation-resistant genetically engineered bacteria.2.The radiation-resistant genetically engineered bacteria was applied to the low concentration of uranium solution(?)reduction of enrichment of uranium in the experiment,solution p H,the fungus dose,uranium enrichment of initial concentration,time and other factors affect the performance of its reduction of enrichment.Using scanning electron microscopy(SEM)and electron energy spectrometer(SEM EDS),Fourier transform infrared spectrometer(FTIR)characterization of genetically engineered bacteria morphology structure before and after the enrichment of uranium,Analysis of changes in elements,moieties,etc,explore its enrichment of uranium(?)behavior.3.By different concentration of hydrogen peroxide stimulate the wild type Deinococcus radiodurans,empty plasmid group Deinococcus radiodurans and radiation-resistant genetically engineered bacteria,and the GSH,SOD,CAT and MDA assay kits were applied to study the possible mechanism of dsrA gene to improve the antioxidant capacity of Deinococcus radiodurans.Results:1.The recombinant plasmid p RADK-dsrA was preserved intact in E.coli DH5? and was able to highly express the m RNA of dsrA reduction gene,and the radiation-resistant genetically engineered bacteria containing the reduction gene dsrA was successfully constructed.2.When the p H value of uranium solution is 5,the initial concentration of uranium is 30 mg/L,the dosage ratio of bacteria is 33%,and the enrichment time is 60 min,the enrichment rate of uranium can reach 92.45%,and the enrichment capacity is 51.08 mg/g.With wild type Deinococcus radiodurans enrichment rate(72.02%)compared to genetically engineered bacteria for enrichment of uranium(?)reduction rate(92.45%)significantly increased.The structure was characterized by scanning electron microscopy combined with electron energy spectroscopy(SEM-EDS)and Fourier transform infrared spectroscopy(FTIR).The enrichment process conforms to the quasi-second-order kinetics model and the Langmuir isotherm model.3.After hydrogen peroxide stimulation,compared with the empty plasmid group,SOD activity increased,MDA content decreased,CAT content increased,and GSH activity increased in the genetically engineered bacteria transformed into dsrA reduction gene.Conclusions:1.The recombinant plasmid PRADK-dsrA was successfully transferred into Deinococcus radiodurans,and the radiation-resistant genetically engineered bacteria was constructed.2.The optimal enrichment conditions of uranium solution by radiation-resistant genetically engineered bacteria are as follows: p H value is 5,initial concentration of uranium is 30 mg/L,dosage ratio of bacteria agent is 33%,enrichment time is 60 min.The enrichment process conforms to the quasi-second-order kinetics model and the Langmuir isotherm model,and is mainly characterized by chemical enrichment.It is speculated that there are chemical bonding and reduction reactions.The uranium enrichment ability of the radiation-resistant genetically engineered bacteria is better than that of the wild-type Deinococcus radiodurans.3.dsrA gene can improve the antioxidant capacity of Deinococcus radiodurans.