Screening Of Rhizosphere Growth Promoting Bacteria And BPA Degrading Bacteria And Study On The Function Growth Promoting Growth Of Maize Seedlings

In recent years,the widespread use of bisphenol A(BPA)has led to its increasing accumulation in farmland so,which has affected the normal growth of crops.The use of microorganisms to alleviate the toxicity of organic pollutants to plants and the use of them to repair contaminated soil have attracted much attention.In this study,12 strains of ACC deaminase producing plant growth promoting bacteria were screened from different plant rhizosphere.According to the characteristics of ACC deaminase producing activity,phosphorus dissolving ability,IAA producing ability and iron carrier producing ability,two strains of YMG3 and ymn YMN3 with better growth promoting ability were screened out.Seven strains of BPA,which can use BPA as carbon source,were isolated from the sludge of a lake.A strain DB4 with better degradation effect was screened out.The three strains were further identified and the growth promoting effect of these three strains on maize seedlings was explored.The strains YMG3,YMN3 and DB4 were identified as Enterobacter sp.,Chrysobacterium sp.and Pseudomonas sp.,respectively.The group inoculated with strains YMG3 and YMN3 were regarded as rhizosphere growth promoting bacteria group,and the group inoculated with strains YNG3,YMN3 and DB4 were regarded as combination bacteria group.The pot experiment of maize growth promoting effect showed that:under the stress of BPA,rhizosphere growth promoting bacteria and combination bacteria increased photosynthesis by increasing chlorophyll content and stomatal conductance,thus increased the biomass of maize;excess active oxygen in leaves and roots was removed by increasing the activity of antioxidant enzymes,so as to reduce MDA content in leaves and roots and the effect of active oxygen on leaves and roots In the absence of BPA stress,inoculation of rhizosphere growth promoting bacteria,BPA degrading bacteria and combination bacteria did not show significant growth promoting effect;under the stress of BPA,BPA degrading bacteria did not show significant growth promoting effect.The results of cluster analysis and correlation analysis showed that the growth and physiological status of maize seedlings in rhizosphere growth promoting bacteria group and combination bacteria group were significantly different from those in unconnected bacteria group and BPA degradation bacteria group,and the activities of antioxidant enzymes and osmotic pressure regulators in leaves and roots had a greater impact on this;the growth promoting bacteria and combination bacteria in rhizosphere mainly improved the leaf by providing chlorophyll content and stomatal conductance,and then improve the biomass of corn seedlings;removing the active oxygen in leaves mainly by improving the activities of GPX,GR and pod in leaves;removing the active oxygen in roots mainly by improving the activities of POD,GR,CAT and SOD in roots;MDA in leaves and roots is mainly oxidized by H₂O₂.To sum up,under the stress of BPA,rhizosphere growth promoting bacteria and combination bacteria can alleviate the toxicity of BPA and promote the growth of maize seedlings.