Zinc solubilization ability of the isolates was detected by spotting
the log phase culture of bacterial strains on Tris-minimal
medium plates having zinc phosphate, and zinc carbonate as source
of insoluble inorganic zinc along with bromophenol blue as pH indicator.
The inoculated plates were then incubated at 28
±
1 ◦C for
3 days, and observed for the clearing zone around the colonies (due
to the solubilization of inorganic zinc by bacteria).