Abstract

Nibha Gupta *, Dolly Sahoo and Uday Chand Basak

Phosphate solubilising ability of five Streptomyces isolated from the phyllosphere of Heritiera fomes grown in Bhitarkanika mangrove ecosystem was evaluated using tricalcium phosphate (TCP) in both plates and broth culture conditions as well as with and without NaCl. Streptomyces ST24 showed highest solubilization of TCP, with 50.8 and 48.0 mm of halo zone in the plate assay done at pH 7.2 and temperatures 30 and 37°C. Streptomyces ST21, ST24 and ST26 showed good solubilization of TCP in culture medium with 52.15, 50.77 and 52.07 µg/ml, respectively. The requirement of NaCl for better solubilization of TCP was observed in all Streptomyces. However, ST23 and ST24 showed solubilization activity without addition of NaCl. Thus the solubilization potential varies among different isolates of Streptomyces. It also differed according to incubation period. Over all, the best solubilization ability of all test Streptomyces could be observed in the presence of 0.2% NaCl. The solubilization might be due to production of acids by the culture, since the pH of the culture broth was changed from initial pH of 7.2 and 9.0 to lower pH values.