Isolation, Purification And Liberation Of Free Phosphate By Indigenous Phosphate Solubilizing Bacteria And Effect On Plant Growth Promotion.

Solubilization of insoluble organic phosphate has been the focus of many studies as it increases the availability of phosphorus to vegetation and improves plant growth. The aim of this study was to study those bacterial strains which were positive for phosphate solubilization in plate assay as well as in liquid media. The isolates which showed efficient phosphate solubilization activity both in plate and liquid media were examined for the release of free phosphate in liquid media. The amount of free phosphate liberated by the organisms was estimated. The efficient phosphate solubilizing bacteria which also released high amount of free phosphate in the media were scrutinized for auxin production via bioassay. Five bacterial isolates CMG851, CMG854, CMG857, CMG860 and CMG861 found positive for auxin production were checked for the production of indole acetic acid and indole butyric acid via high performance liquid chromatography (HPLC). The amounts of indole acetic acid and indole butyric acid were also estimated. These five efficient phosphate solubilizing and auxin producing bacterial isolates were identified via 16srRNA analysis. They were Acinetobacter lwofii (CMG851), Pseudomonas aeruginosa (CMG860) and Bacillus thuringiensis (CMG854, CMG857, CMG861) showed efficient phosphate solubilization and auxin production abilities. Mung beans were selected to study the effect of plant growth promotion abilities by the three phosphate solubilizing and auxin producing bacteria. The root and shoot length of Rye plants were measured and it was found that the selected bacteria had noticeable effect on them.