Enhanced heavy metal immobilization by a bacterial-chitosan complex in soil

Soil contaminated with heavy metals (e.g., Pb²⁺, Cu²⁺, and Zn²⁺) was treated with aminopoly-saccharide chitosan alone or a strain of the bacterium Bacillus subtilis to determine their effects on metal ion accumulations. Phosphatase and Chitosanase production were also assayed. The combined bacterial-chitosan treatment showed the greater accumulation of Zn²⁺ followed by Cu²⁺ as compared to single treatments, while Pb²⁺ did not show a marked accumulation by either single or combined treatments.