Analysis Of Bacterial Community Structure In Rhizosphere Soil Of Peanut

The purpose of this study was to research the relation between bacterial communitystructure with physicochemical property of the peanut rhizosphere soil; the regularity ofdistribution and the genetic diversity of siderophores bacteria from rhizosphere soil of peanut;screen the strain for activating Fe in the soil. The research collected rhizosphere soil of peanutat4sample points which was selected according to the four agrotype in Shandong province:brown soil, cinnamon soil, moisture soil and Shajiang black soil. Both the the ironchlorosis(H) and normal(Z) peanut plants were collected from each place, addition with thenon-rhizosphere soil from brown soil. There were9samples in total. The genetic diversity ofsiderophores bacteria from rhizosphere soil of peanut was analysed by screening them andanalyzing with ARDRA. Molecular biology methods including T-RFLP and16s rDNA,combined with the methods PCA, CCA and RDA were used to discuss the influence onbacterial community structure of rhizosphere soil of peanut.There were139siderophores bacteria had been screened from the rhizosphere soil ofpeanut in total. They belonged to these phylas (or subphylums) as followed: β-Proteobacteria,γ-Proteobacteria, Bacteroidetes, Firmicutes, Verrucomicrobia, Gemmatimonadetes,Actinobacteria. There were38Bacillus and20Pseudomonas, taking up42%of thesiderophores bacteria in total. These two phyla also took up a large proportion in all the16SrDNA clone libraries. More than90%of the Bacillus was only found in the rhizosphere soilof chlorosis peanut, while Pseudomonas was found in all libraries.Members of peanut rhizobacteria communities in Shandong included12phyla (orsubphylum): Proteobacteria (including α-Proteobacteria, β-Proteobacteria, δ-Proteobacteria,γ-Proteobacteria), Acidobacteria, Planctomycetes, Bacteroidetes, Firmicutes, Verrucomicr-obia, Nitrospira, Chloroflexi, Gemmatimonadetes, Cyanobacteria, Actinobacteria, and someunclassified bacteria. Bacterial diversity and composition displayed noticeable spatial and temporal variations at4stations. Acidobacteria and Firmicutes sequences were dominated inall9clone libraries derived. The higher bacterial diversity was present in normal samples andthe lower diversity in those collected in chlorosis peanut. The results of PCA showed thebacterial communities had obvious differences between the rhizosphere soil andnon-rhizosphere soil, which indicated that the activities of roots has a most remarkableinfluence on the bacterial communities. There was also a distinction between the rhizospheresoil which were collected from the chlorosis and normal peanut, while there was a smallerdistinction when the samples were compared among the agrotype. This stated that it has amore obvious influence on the bacterial communities from the chlorosis than the agrotype.The results of CCA and RDA indicated that Fe and pH was the most important environmentalfactors to influence the structure of bacterial communities in rhizosphere soil of peanut.γ-Proteobacteria showed the highest positive correlation with concentration of Fe. Firmicutes,α-Proteobacteria, β-Proteobacteria, γ-Proteobacteria, Bacteroidetes, Acidobacteria,Actinobacteria, Cyanobacteria and Gemmatimonadetes were all positively correlated with Fe,Cu, Organic Matter and Humus, while they were all negatively correlated with Mn, Zn,Ammonium Nitrogen, Nitrate Nitrogen, pH. Additionally, δ-Proteobacteria, Verrucomicrobia,Nitrospira, Chloroflexi, and Planctomycetes were all negatively correlated with Fe, Cu,Organic Matter and Humus and positively correlated with Mn, Zn, Ammonium Nitrogen,Nitrate Nitrogen, pH. The results of CCA based on T-RFLP suggested that the abundance ofall T-RFs were significant affected by environmental factors, except K.The research provided theories on activating Fe in the soil, and remitting peanutchlorosis which was caused by the lack of Fe. The research also enriched agriculturalmicrobial resources.