Bioremediation and Recovery of Lead and Cadmium by Spores of Bacillus subtilis C1

Spores of a hot spring isolated strain of Bacillus subtilis were tested as a biotechnological tool to be used for the detoxification and bioremedition of heavy metals. Lead and cadmium were efficiently adsorbed by B. subtilis spores with those of C1 more efficient than those of the lab collection strain PY79. Metal-adsorption did not alter the functionality of C1 spores that were still fully resistant to heat, ethanol or chloroform and able to germinate after the interaction with Cd²⁺ or Pb²⁺. The spore-adsorbed metals were released upon disruption of the spore coat layers, suggesting that the metals were mostly accumulated within the spore coat. Heat-inactivated spores released almost all adsorbed metals, allowing the recovery of Cd²⁺ and Pb²⁺. While Cd²⁺ polluted water impaired the normal germination and growth of seeds of the model plant Arabidopsis thaliana, treatment of the polluted water with C1 spores restored plant growth.