Research On Effects Of Direct Current Fields On Soil Microbial Communities With PCR-DGGE

In the recent years, with the development of industrial and agricultural and the acceleration of urbanization, soil pollution has dramatically increased, so the new technologies of contaminated soils remediation have been considerably developped in the field of environmental protection. Today, the electrokinetic bioremediation technology as a technology of potential and forefront is extensive attendef at home and abroad, but the change of soil microbial communities under electric fields influences the efficacy of using direct current fields to accelerate process of PHytoremediation. Hence,in this study, the change of soil microbial communities were investigated through direct current field ,which is supposed of provide a theory basis for soil electrokinetic bioremediation technology.There were mainly the following several parts of research in this study:1. PCR-DGGE analysis method was optimized, on the one hand PCR system has been optimized ,so that the total soil DNA 16 SrDNA the specificity of PCR Product was best;The denaturants concentration change from 35%-55% in (DGGE) method agent concentration,there are the best separate efficiency, the conclusions added new a quick, accurate method for soil microorganisms under electric field.2. The diversity and similarity of rhizosPHeric soil microbial communities under different electric fields were investigated through an improved PCR-DGGE analysis and the mechanisms by which electric fields influence soil microbial communities were further analyzed. The results showed that the induced change in soil properties such as soil PH, the mobilization of soil bacterial cells in electric fields, the lethal effect of electric fields with over high strength, and the induced alteration of gene regulation patterns in response peysiologically to environmental stress and change might be the main mechanisms that influence soil microbial communities in electric fields.In the same test conditions, the greater the electric field intensity,the greater microbial community changes and the impact of Non-uniform field on the microbial community was more evident than the uniform electricfield,While the rhizosPHeric soil microbial communities diversity had been obviously increased as the smaller spacing of polarity switch.3. The diversity and similarity of non-rhizosPHeric soil microbial communities under different electric fields were investigated through anl6SrDNA DGGE separation result chart and Shannon index analysis. The results showed that the diversity and structure of non-rhizosPHeric soil microbial communities were greatly affected by the type and strength of electric fields and the application method.Their diversity was increased in a proper electric field, while their diversity was reduced and their structure was changed in otherwise.The results of this study showed that in order to avoid the detrimental effects on soil microbial communities, it is necessary to adopt an appropriate electric field when using electric fields to accelerate the process of bioremediation. That is, the appropriate electric field should be a uniform electric field in the strength of 1.0V/cm with the reversal time interval of 10 min in rhizosPHere soil; while the appropriate electric field should be a uniform electric field in the strength of 1.5V/cm in non-rhizosPHere soil.