Phosphate-dissolving bacteria in the rhizosphere of some cultivated legumes

Twelve phosphate-solubilising organisms were isolated from the rhizosphere of four cultivated legumes growing in four soil regions of India. These organisms were identified as Bacillus megaterium, B. subtilis, B. brevis, B. pulvifaciens, B. pumilus and B. polymyxa. All the organisms except B. megaterium and one strain of B. pulvifaciens solubilised significantlygreater amounts of tricalcium phosphate over uninoculated control in liquid medium. Rhizospheres of Trifolium alexandrinum and Phaseolus aureus appear to provide more suitable environment for phosphate-dissolving organisms than those of Crotalaria júncea and Sesbania aculeata.