Screening growth-promoting rhizobacteria from main tobacco-growing areas in Sichuan and construction of growth-promoting rhizobacteria groups

To explore growth-promoting rhizobacteria (GPR) resources in main tobacco-growing areas in Sichuan, rhizosphere soil samples were collected from five main tobacco-growing areas. Plate dilution method was used to isolate microorganism. GPR were screened by determining IAA, siderophore and HCN production abilities of strains, and from which GPR groups were constructed. The effects of GPR groups on germinating rates of tobacco seeds from three cultivars were analyzed. The results showed that in the 923 isolated strains, five bacterial strains (YBT-003-B-5, YB-001-B-8, FY-001-B-9, MT-002-B-12 and L2-001-B-16) had better growth-promoting abilities. GPR group 1345 (including strains YBT-003-B-5, FY-001-B-9, MT-002-B-12 and L2-001-B-16) significantly promoted the germinating rates of tobacco seeds. Analysis of 16S rDNA sequences indicated that strains YBT-003-B-5, FY-001-B-9 and MT-002-B-12 belonged to Bacillus tequilensis, Enterobacter xiangfangensi and Klebsiella variicola respectively, and stain L2-001-B-16 might be a new species belonging to Enterobacteriaceae.