Rhizosphere bacteria enhance the accumulation of selenium and mercury in wetland plants

The role of rhizosphere bacteria in facilitating Se and Hg accumulation in two wetland plants, saltmarsh bulrush (Scirpus robustus Pursh) and rabbit-f oot grass (Polypogon monspeliensis (L.) Desf.), was studied. Ampicillin-ame nded plants (i.e., with inhibited rhizosphere bacteria) supplied with Na2Se O4 or HgCl2 had significantly lower concentrations of Se and Hg, respective ly, in roots than plants without ampicillin. These results were confirmed b y inoculating axenic saltmarsh bulrush plants with bacteria isolated from t he rhizosphere of plants collected from the field; these plants accumulated significantly more Se and Hg compared to axenic controls. Therefore, rhizo sphere bacteria can increase the efficiency of Se and Hg phytoremediation b y promoting the accumulation of Se and Hg in tissues of wetland plants.