Characterization of PSB's from Rhizospheric Soil

Seven phosphate solubilising bacteria, belonging to Enterobacteriaceae family, capable of utilizing Xylose and rock phosphate as the sole carbon and phosphate source were isolated by enrichment culture method. This PSB exhibited mineral phosphate solubilising (MPS) phenotype on xylose and glucose, which are substrates for enzyme glucose dehydrogenase (GDH), as carbon sources. The isolates secreted formic acid and xylonic acid by utilizing xylose. In all the isolates, GDH activity was found when grown on Glucose and Xylose, indicating that it is constitutive and could act on a wide range of aldose sugars. PFL enzyme activity in all xylose utilizing cells was higher, since PFL is a marker of anaerobic conditions thus all the isolates were facultative anaerobes. Efficiency of the isolates for phosphorus solubilization in natural environments was further confirmed by pot experiments on mung bean plants.