ISOLATION AND BIOCHEMICAL CHARACTERIZATION OF PHOSPHATE SOLUBILIZING MICROBES

Phosphorus (P) is one of the essential macronutrients for plant growth and reproduction. Plants acquire Pfrom the soil solution as phosphate anions. However, phosphate anions are extremely reactive and may be immobilizedthrough precipitation with cations such as Ca2+, Mg2+, Fe3+ and Al3+, depending on the particular properties of thesoil and as a result, the phosphate is highly insoluble and unavailable to plants. Application of phosphate-solubilizingfungi (PSF) has been added as fertilizer to increase P uptake and plant growth. The improvement of soil fertility is oneof the most common strategies to increase agricultural production. Maintaining high levels of available nitrogen (N) andphosphorus (P), the two most limiting nutrients in soil, remains being a challenge.Major researches on biofertilizer have concentrated on understanding and improving N2 fixation. However, it is knownthat every aspect of the process of nodule formation is limited by the availability of P. Legumes like alfalfa and clovershow a high positive response to P supplementation (Gyaneshwar et al., 2002), but most of the supplemented Pbecome unavailable when its reacts with soil components.Many soil microorganisms are able to solubilize this unavailable P through their metabolic activities exudating organicacids, which directly dissolve the rock phosphate, or chelating calcium ions that release P to the solution. Production ofmicrobial metabolites results in a decrease in soil pH, which probably plays an important role in the solubilization (Abd-Alla, 1994).Phosphate solubilizing bacteria (PSB) were isolated from the area around Bidar region and screened on the basis oftheir solubilization of inorganic tricalcium phosphate in liquid cultures. Ten strains that had higher solubilization potentialwere selected, and they characterized