Abstract:[Objective] We explored plant growth promoting rhizobacteria with strong activity of resisting nickel and secreting siderophore, and studied their effect on promoting peanut plant growth and absorbing nickel. [Methods] Strains with strong siderophore secreting capacity were isolated from peanut rhizosphere by using qualitative and quantitative test of CAS (chrome azurol S) medium. Siderophore secreting strains were identified by similarity and phylogenetic analysis of 16S rRNA gene. Tolerance of siderophore secreting strains to nickel was measured by beef extract-peptone medium supplemented with nickel ion. In the pot experiment of peanut, effects of siderophore secreting strains on peanut plant was analyzed by measuring shoot height, root length, biomass and the content of nitrogen, phosphorus, potassium and nickel in peanut plant. [Results] Five Bacillus strains with siderophore secreting capacity were isolated from peanut rhizosphere. Bacillus sp. HSGJ1 showed the strongest siderophore secreting capacity among the five strains. It secreted 156.56 mg/L of siderophore after 2 days. Bacillus sp. HSGJ1 showed strong tolerance to nickel with 150 mg/L of minimum lethal concentration. HSGJ1 could promote plant growth, increase the biomass and nitrogen, phosphorus and potassium contents of peanut, and decrease the nickel content in the root and shoot of peanut plant in 50 and 100 mg/kg of Ni2+ in pot soil. [Conclusion] As a good plant growth promoting rhizobacterium, the siderophore secreting Bacillus sp. HSGJ1 can be applied for planting crop in the nickel contaminated soil to improve crop tolerance under nickel stress and decrease nickel accumulating in crop. Therefore, Bacillus sp. HSGJ1 shows good application value.
