containing tricalcium phosphate (Ca3 (PO4)2 ) as insoluble phosphate source.Cells were grown overnight in LB medium, next they were washed twice with 0.9% NaCl and resuspended in 0.9% NaCl to produce equal cell densities among. Solutions were inoculated on the agar plates and incubated at 30◦C, and observed daily for 7 days for the appearance of transparent “halos” (Katznelson and Bose, 1959).Experiments were performed in triplicate.Phosphorus solubilization index was measured using the following formula