Rhizofiltration of Lead Contaminated Soil by Helianthus annuus amended with Bacillus megaterium and EDTA
Heavy metal contamination causes numerous adverse effects to public health and the environment. Sources of heavy metal contamination are widespread, especially in urban environments. Certain plants such as sunflower (Helianthus annuus) have been shown to sequester heavy metals in their root systems, thus filtering contaminants such as lead (Pb) from soil, a process termed rhizofiltration. In the present study, Bacillus megaterium was applied to the root system of sunflowers growing in Pb-contaminated soil and the efficiency of rhizofiltration was examined. Lead levels in the rhizosphere of the Bacillus megaterium and EDTA amended plants were almost 100 mg/kg soil higher than those without treatment, suggesting the amendment may have been effective in augmenting lead sequestration. In order to further elucidate these lead-sequestering communities, preliminary phylogenetic assays were conducted on the soil with and without the presence of the plant. Although complete coverage of the community phylogeny was not possible, there was evidence indicating that the rhizosphere may have induced changes in the composition of the bacterial community. These studies offer simple methods for enhancing bioremediation in agriculture.