Solubilization of zinc salts by a bacterium isolated from the air environment of a tannery

Airborne bacteria isolated from a tannery air environment were screened for the property of solubilization of insoluble zinc oxide and zinc phosphate. Out of 10 strains tested, a strain of Pseudomonas aeruginosa (CMG 823) showed the best solubilization and solubilized both zinc oxide and zinc phosphate. Colonies of the bacterium produced clear haloes on solid medium which contained these insoluble metal compounds, but only when glucose was provided as a carbon source. Solubilization of zinc oxide and phosphate was accompanied by an increase in the H+ concentration of the medium, probably a consequence of the production of 2-ketogluconic acid.