Abstract
Phosphate compounds have been used for the immobilization of heavy metals in contaminated environments. In this study, phosphate-solubilizing bacteria (PSB) were isolated from phosphate-amended and lead (Pb)-contaminated soils, and their effects on phosphate-induced immobilization of Pb were examined. Two isolated PSB strains, CS2-B1 and SM1-B1, which were putatively identified as Pantoea sp. and Enterobacter sp., respectively, were able to solubilize phosphorous (P) from insoluble P sources through the release of organic acids. Strains CS2-B1 and SM1-B1 solubilized 479mg/L and 293mg/L, respectively, of P from tricalcium phosphate. The addition of either CS2-B1 or SM1-B1 and various P amendments into Pb-contaminated soil reduced the NH_4NO_3-extractable Pb concentration, with a 51% increase in the immobilization of Pb observed in rock phosphate-amended soil containing SM1-Blover control soil lacking added PSB. This study indicates that PSB increase the solubility of P in soil, thereby leading to effective immobilization of Pb in contaminated soils.
