Bioremediation of heavy metals by growing hyperaccumulaor endophytic bacterium Bacillus sp. L14.

Heavy metal bioremediation by a multi-metal resistant endophytic bacteria L14 (EB L14) isolated from the cadmium hyperaccumulator Solanum nigrum L. was characterized for its potential application in metal treatment. 16S rDNA analysis revealed that this endophyte belonged to Bacillus sp. The hormesis of EB L14 were observed in presence of divalent heavy metals (Cu (II), Cd (II) and Pb (II)) at a relatively lower concentration (10mg/L). Such hormesis was the side effect of abnormal activities increases of ATPase which was planned to provide energy to help EB L14 reduce the toxicity of heavy metals by exporting the cations. Within 24h incubation, EB L14 could specifically uptake 75.78%, 80.48%, 21.25% of Cd (II), Pb (II) and Cu (II) under the initial concentration of 10mg/L. However, nearly no chromium uptake was observed. The mechanism study indicated that its remediation efficiencies may be greatly promoted through inhibiting the activities of ATPase. The excellent adaptation abilities and promising remediation efficiencies strongly indicated the superiority of this endophyte in heavy metal bioremediation at low concentrations, which could be useful for developing efficient metal removal system.