Evaluation of Phosphorus Solubilisation by Microorganisms Isolated from Aridisols

The population of phosphate solubilizing microorganisms was generally low in desertic soils (Aridisols) possibly due to the low level of organic matter and high temperature regime. Bacillus cereus, Pseudomonas florescens, Penicillium pinophillum, and Aspergillus niger were some of the predominant phosphorus solubilizers found in majority of the soils. In vitro evaluation of these cultures indicated that fungi were more efficient than bacteria in phosphorus solubilization. Phosphorus release by all the organisms was associated with the production of organic acids like lactic, glycollic and succinic in the medium. The solubilizing effect of A. niger was progressively enhanced by increasing glucose concentration (0.5 to 2.0%) in the medium, but with rock phosphate such enhancement was not observed beyond 0.25%.