Stress Induced Phosphate Solubilization by Aspergillus awamori bxq33110 Isolated from Waste Mushroom Bed of Agaricus bisporus

A fungal strain, capable of solubilizing insoluble phosphate under diverse temperature, pH and salt conditions was isolated from Waste Mushroom bed of Agaricus bisporus in South Korea. Based on 18S rRNA analysis, the strain was identified as Aspergillus awamori bxq33110. The strain showed maximum phosphate solubilization in AYG medium (525 ㎍ mL-¹) followed by NBRIP medium (515 ㎍ mL-¹). The strain solubilized Ca₃(PO₄)₂ to a greater extent and rock phosphate and FePO₄ to a certain extent. However AlPO₄ solubilizing ability of the strain was found to be very low. Glucose at the rate of 2% (561 ㎍ mL-¹) was found be the best carbon source for Aspergillus awamori bxq33110 to solubilize maximum amount of phosphate. However, no significant difference (P less than or equal to 0.05) in phosphorus solubilization was found between 1% and 2% glucose concentrations. (NH₄)₂SO₄ was the best nitrogen source for Aspergillus awamori bxq33110 followed by NH₄Cl and NH₄NO₃. At pH 7, temperature 30℃ and 5% salt concentration (674 ㎍ mL-¹) were found to be the optimal conditions for insoluble phosphate solubilization. However, strain Aspergillus awamori bxq33110 was shown to have the ability to solublize phosphate under different stress conditions at 30-40℃ temperature, pH 7-10 and 0-10% salt concentrations indicating it' potential to be used as bio-inoculants in different environmental conditions.