Int.J.Curr.Microbiol.App.Sci (2013) 2(5): 83-88 83 Original Research Article Isolation, characterization and antagonistic effect of phosphate solubilizing microorganisms from Vigna radiata L. Rhizospheric soil M.Kannahi* and N.Umaragini P.G and Research Department of Microbiology and Division of Biotechnology STET Women s college, Mannargudi, Tamil Nadu, India *Corresponding author e-mail: kannahisri79@gmail.com ABSTRACT Introduction Phosphorus, the second most important micronutrient required by the plants, next to nitrogen, is reported to be a critical factor of many crop production system, due to the fact that the limited availability in soluble forms in the soils (Xiao et al., 2011). Microbes present in the soil employ different strategies to make use of unavailable forms of phosphorus and in turn also help in making phosphorus available for plant to absorb. When phosphoric fertilizers are applied to the soil they often become insoluble (more than 70%) and are convert into complexes and in phosphate in the soil (Mittal et al., 2008 involved in the solubilization of insoluble phosphorus include bacteria, fungi, actinomycetes . Microorganisms and arbuscular mycorrhial (VAM) fungi (Khan et al., 2007; Wani et al., 2007; Xiao et al., 2009). Numerous rhizosphere microorganisms possessing phosphate solubilizing activity are reported (Mittal et al., 2008). Among the soil bacterial communities, ectorhizosphere strains from Bacillus and Pseudomonas(Wani et al., 2007). And endosymbiotic rhizobia have been described as effective phosphate solubilizers (Igualet al., 2001) strains from bacterial genera Pseudomonas, ISSN: 2319-7706 Volume 2 Number 5 (2013) pp. 83-88 http://www.ijcmas.com Keywords Phosphate solubilizing microbes; Tricalcium phosphate; NBRIP; Pikovskayas Medium. Phosphorus is the second most important micronutrient required by the plants, next to nitrogen, is reported to be a critical factor of many crop production system. Microorganisms involved in the solubilization of insoluble phosphorus. From the rhizospheric soil of Vigna radiate L. phopsphate solubilizing bacteria like P.fluorescens and B.subtilis were isolated and fungi like A.niger and F.oxysporum were isolated. Then the PSM solubilizing activity was determined in National Botanical Reasearch Institute Phosphate Growth Medium and Pikovskayas agar medium. Then the phosphatase activity was determined by using spectrophotometer. Then finally antagonistic effect of PSM were also determined. These microorganisms mediate soil processes such as exudation of soluble compounds, storage and release of nutrients and water etc.