Bacteria Community Composition And Isolation And Characterization Of PGPR In Rhizosphere Of Caragana Spp

Plant growth-promoting rhizobacteria is a kind of beneficial microorganism which can colonize the plant's microenvironment and promote plant growth.Exploring and using efficient PGPR are great significance for the development of modern agriculture and environmental restoration and governance,etc.In this study,the sand-fixing plant Caragana spp.form Ningxia province were studied.We surveyed bacteria community Composition of rhizosphere soil of Caragana spp.by high-throughput sequencing.Meanwhile,PGPR with growth-promoting properties were isolated from rhizosphere soil and built it's phylogenetic trees based on 16S rDNA sequence.Moreover,the excellent growth promoting strains were screened by the determination of the growth characteristics of the strains and verified their promoting effect.The results of the project will provide a basis for better development microbial agents,and enrichment of microbial resources,and promote the protection,development and utilization of microbial resources in arid areas.The main contents and results are as follows:(1)The results showed that the bacterial Community Composition in the rhizosphere soil of Caragana spp.were 27 Phylum,55 Class,95 Order,183 Family and 217 Genus.The main phylum includes Firmicutes(31.77%),Proteobacteria(25.11%),Actinobacteria(18.68%),and the main family is Bacillaceae(26.08%),and the main genus includes Bacillus(26.08%),Acinetobacter(4.01%),Sphingomonas(1.60%),Solirubrobacter(1.60%),Arthrobacter(1.51,%),Lactococcus(1.11%),et al,and Bacillus is a dominant genus.(2)5 strains of ACC-deaminase were obtained by screening with 1-Aminocyclopropane-1-carboxylate deaminase(ACC)as the sole nitrogen source,which belonged to Enterobacter cloacae and Arthrobacter;14 strains of siderophore-producting were screened by Chrome azurol S medium,which were identified as mainly pseudomonas.9 strains of organic phosphorus-solubilizing and 12 strains of inorganic phosphate-dissolving were screened by using lecithin and calcium phosphate as the sole phosphorus source mediums,and the strains mainly belonged to Pseudomonas,Enterobacter cloacae,Agrobacterium,Bacillus and Serratia.(3)The activities of secrete IAA,siderophore-producting and nitrogen fixation of strains were measured.The results showed that most of the strains had more than three kinds of promoting agents,and four high-efficient strains AC3,Fell,YP2 and WP8 were screened for back-inoculation experiment.The results showed that the four strains were highly effective in promoting the growth of Caragana spp.Seedlings,and Promoting the effect under the indoor natural conditions were more obviousis than that at growth cabinet conditions.Among them,Enterobacter cloacae AC3 and Pseudomonas YP2 were highly effective in promoting the growth,which had the potential for the development of microbial agents.(4)Microbial diversity of soil in Caragana spp rhizosphere was abundant,and Bacillus was the absolute dominant group.Pseudomonas and Enterobacter cloacae were mainly growth-promoting bacterias,and most of them are widely of growth-promoting trait,and the ability of growth-promoting were strong with the development potential.