A modified plate assay for screening phosphate solubilizing microorganisms.

Inorganic phosphate solubilizers are routinely screened in the laboratory by a plate assay method (9) using either Pikovskaya agar (17) or Sperber agar (21). Any microorganism which is capable of producing a halo/clear zone is selected as a potential phosphate solubilizer (3, 5, 6,13). This halo produced is due to the solubilization of insoluble phosphates, which in turn is largely due to the production of organic acids into the surrounding medium (4,(6)(7)(8)(10)(11)(12)16,19,20).