Search

Two cadmium (Cd)-resistant strains Pseudomonas sp. RJ10 and Bacillus sp. RJ16 were investigated for their effects on the soil Cd and lead (Pb) solubilization and promotion of plant growth and Cd and Pb uptakes of a Cd-hyperaccumulator tomato. In the heavy metal-contaminated inoculated soil, the CaCl2-extractable Cd and Pb were increased by 58¿104% and 67¿93%, respectively, compared to the uninoculation control. The bacteria produced indole acetic acid, siderophore and 1-aminocyclopropane-1-carboxylate deaminase. Root elongation assay conducted on tomato under gnotobiotic conditions demonstrated increase in root elongation of inoculated tomato seedlings compared to the control plants. An increase in Cd and Pb contents of above-ground tissues varied from 92% to 113% and from 73% to 79% in inoculated plants growing in heavy metal-contaminated soil compared to the uninoculation control, respectively. These results show that the bacteria could be exploited for bacteria enhanced-phytoextraction of Cd- and Pb-polluted soils. [Copyright &y& Elsevier]

Abstract: Two lead (Pb)-resistant endophytic bacteria were isolated from rape roots grown in heavy metal-contaminated soils and characterized. A pot experiment was conducted for investigating the capability of the two isolates to promote the growth and Pb uptake of rape from Pb-amended soil. The two isolates were identified as Pseudomonas fluorescens G10 and Microbacterium sp. G16 based on the 16S rDNA gene sequence analysis. Strains G10 and G16 exhibited different multiple heavy metal and antibiotic resistance characteristics and increased water-soluble Pb in solution and in Pb-added soil. Root elongation assays demonstrated increases in root elongation of inoculated rape seedlings compared to the control plants. Strain G16 produced indole acetic acid, siderophores and 1-aminocyclopropane-1-carboxylate deaminase. Increases in biomass production and total Pb uptake in the bacteria-inoculated plants were obtained compared to the control. The two strains could colonize the root interior and rhizosphere soil of rape after root inoculation. [Copyright &y& Elsevier]