Study On The Capacity Of Arsenite-oxidizing Bacteria GD03 To Restore The Arsenite Contaminant In Paddy Soil

High toxic trivalent arsenic[As(?)]is the predominant arsenic speciation in the soil solution when rice was cultivated under flooding.Since As(?)can be carried into rice roots by its silicon transportation channel,paddy rice has become one of the most important passways of arsenic exposure for people all over the world.Therefore,the study to alleviate the toxicity of As(?)on the growth of rice plants and decrease arsenic accumulation in paddy rice has important theoretical significance and practical value for the increase of rice yields and the improvement of rice quality.Microbial remediation for heavy metal pollution have the advantages such as environmental-friendly and easy to operate.In this study,the cultivar of Guangyou Ming 118 was chosen as experimental material,potting soil cultivation was used to investigate the effect of monoclonal arsenite-oxidation bacterium GD03 on the physical and chemical properties of soil solution,the toxicity of As(?)on the growth of rice plants and arsenic transportation from soil solution to rice plants after different ratio of GD03 was inoculated into arsenite-contaminated soil,to provide a theoretical basis and practical guidance for the study how to control arsenic toxicity on rice.The main results were as follows:1.When rice was cultivated to different stages under the stress of As(?),GD03 significantly increased the value of the redox potential(Eh)in soil solution,significantly promoted the oxidation of As(?)in the soil solution,significantly decreased the pH value and the concentration of total organic carbon(TOC),inorganic carbon(IC),total carbon(TC),total nitrogen(TN),total arsenic and As(?)in soil solution.when the inoculation ratio of GD03 is 4.00 mL/100 g soil,the Eh value in its soil solution was the highest,while the pH value in its soil solution was the lowest and the concentration of TOC,IC,TC and TN in its soil solution was also the lowest.2.When rice was cultivated to maturing stage under the stress of As(?),GD03 significantly increased the morphological indexes such as the dried weight of rice roots,rice stems and rice leaves and rice height,significantly increased the production indexes such as rice yields,the number of per panicle,the setting percentage and the thousand-grain weight of paddy rice.When the inoculation ratio of GD03 is 4.00 mL/100 g soil,Guangyou Ming 118 had the best morphological indexes and the highest production indexes,which showed that the inoculation ratio of GD03 at 4.00 mL/100 g soil has the best restoration effect on arsenite-contaminated paddy soil.3.When rice was cultivated to maturing stage under the stress of As(?),GD03 significantly decreased the concentration of As(?)in rice stems,rice leaves?rice grains and rice husks of Guangyou Ming 118.When the inoculation ratio of GD03 is 4.00 mL/100 g soil,the concentration of As(?)in rice stems,rice leaves>rice grains and rice husks of Guangyou Ming 118 was the lowest.In summary,the chemical speciation of arsenic contaminants in the environment is the key to determine its toxicity and transportation.When rice was cultivated to different stages under the stress of As(?),GD03 significantly promoted the oxidation of As(?)in soil solution and decreased the concentration of As(?)in soil solution;When rice was cultivated to maturing stage under the stress of As(?),the morphological indexes,such as the dried weight of rice roots,rice stems and rice leaves and rice height,and the production indexes were all significantly increased,while the concentration of As(?)in rice stems,rice leaves,rice grains and rice husks was significantly decreased.Therefore,GD03 significantly decreased the toxicity of As(?)on rice plants and inhibited the transportation of arsenic contaminants from paddy soil to rice plants.