Effects Of Plant Growth Promoting Rhizobacteria Mixture EG03 On Rhizosphere Microbial Community Structure And Functional Diversities

The biocontrol efficiency of the five single bacterium strains and the bacterial mixture EG03 against capsicum bacterial wilt were studied by the greenhouse test and field test,The structure and functional diversities of rhizosphere microbial communities were evaluated by using dependent-culture method and sole-carbon-source utilization (SCSU) technique. Different soil samples were collected from the same plot in Huaian, Jangsu, which were affected by EG03. Soil S1 was collected from the plot before usage of EG03, control soil S2 and treatment soil S3 was collected after 10 day from the same plot was Inoculated with EG03, control soil S4 and treatment soil S5 was collected after 50 day from the same plot was Inoculated with EG03. The objectives of this study were to research the biocontrol efficiencies of EG03 In greenhouse test and field plot tests, to identify the differences of structure and functional diversities between treatment soils which were Inoculated with EG03 and control soils, to reveal the effects of the Inoculation with on structure and functional diversities of the rhizosphere microbial communities.In the greenhouse test, the biocontrol efficiencies of the mixture and individual bacterium suspension were 91.1% and 74.7% respectively, with that of the mixture AR99 being the highest. In the field plot tests ,the disease control efficiencies of AR99 were 85.8% , after 50 days treatment.Culture results of the soil samples showed that there were significant difference in the changes In the rhizosphere microbial communities after Inoculation with EG03,but the time after Inoculation with EG03 affect the changes In the rhizpsphere communities. For 7 day after Inoculation,the quantity of rhizobacteria decreased strikingly,nevertheless for 50 day after Inoculation the quantity of rhizobacteria Increased to the higher level than the control soil.SCSU patterns of rhizosphere microbial communities indicated that abilities of SCSU of rhizosphere microbial communities for 50 day after Inoculation were the highest in five rhizosphere soil ,however, for 7 day after Inoculation the abilities of SCSU of rhizosphere microbial communities were the lowest in five rhizosphere soil . Significant differences in functional diversity were found between the treatment rhizosphere soil communities and the control rhizosphere soil communities for 7 day after Inoculation .For 7 day after Inoculation, there were significant differences In the commonest species and uniformity of functional diversity between the treatment and the control rhizosphere soil communities .Composite analysis of above two methods suggested that inoculation with EG03 had significant effect on constructure and functional diversity of the rhizosphere microbial communities ,but this effect changed because of collected time after treatment. Results of above two methods can be attributed to explain the excellent biocontrol efficiencies of EG03 against capsicum bacterial wilt from the aspect of constructure and functional diversity of the rhizosphere microbial communities.