Four bacterial isolates were examined for their ability
to solubilize Cr, Cu, Pb and Zn in soils and for their
effect on metals uptake by Zea mays and Sorghum
bicolor plants. Bacillus subtilis DQ494445; Bacillus
pumilus DQ49446, Pseudomonas pseudoalcaligenes
DQ494447, and Brevibacterium halotolerans
DQ494448 were added to Cr-rich soils and Cu-rich
soils. B. pumilus and B. subtilis increase the
availability of water-soluble Cr in tannery effluent
polluted soil by 4.9- and 2.6-folds, respectively
compared to axenic media. The products of B. subtilis
growth increased Zn, Pb, Cu, and Cr extraction from
copper rich soils by 30, 5.8, 4.3- and 1.2- fold,
respectively, compared to axenic media. The highest
concentrations of Pb (0.2g kg-1), Zn (4g kg-1) and Cu
(2g kg-1) were accumulated in shoots of Z. mays
inoculated with B. halotolerans. The highest
concentrations of Cr (5g kg-1) were accumulated in S.
bicolor roots inoculated with a mixed inoculum's of
bacterial strains. These results show that bacteria
play an important role in increasing the availability of
water soluble metals in soil, thus enhancing Cr, Pb,
Zn and Cu accumulation in Z. mays and S. bicolor
plants.
Key words: Bacteria, Bioavailability, Heavy metals, Phytoremediation
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