ISOLATION AND MOLECULAR CHARACTERIZATION OF PHOSPHATE SOLUBILIZING BACTERIA FROM RHIZOSPHERIC SOILS OF TROPICAL LOWLAND RICE

Phosphate-solubilizing bacteria (PSB) can promote the dissolution of insoluble phosphorus in soil, enhancing the availability of soluble P and reducing the consumption of fertilizer and aid in sustainable agricultural development. The phosphate solubilising bacteria were isolated from the rhizospheric soils of the experimental site located in the ICAR-National Rice Research Institute's experimental farm in Cuttack, India. & the population of PSBs varied between 1-22.5 cfu/gm*104 and higher in DSR (Direct seeded rice) compared to TPR (Transplanted rice). Phosphate solubilization efficiency (PSE) of the isolates gave better result in Pikovskaya’s agar medium plates i.e. 188.9% in K6 (Kasalath, P80, DSR) rather than National Botanical Research Institute’s Phosphate growth medium (NBRIP) i.e. 73.3% for K6. The highest PSE% in C sources was found in lactose i.e. 166.7% for the isolate K9 (Kasalath, P0, DSR) and 180.0% for the isolate D17 (Dular, P80, TPR) for potassium nitrate as N source. The morphological study by staining characteristics showed that all the isolates were gram negative and cocci except D19 (Dular, P80, TPR) which was gram positive and rod shaped. Amplified fragments of oligonucleotide primers in RAPD characterization showed 51.81% polymorphism and 44.54% monomorphism. Based on dendrogram all the isolates were placed in group A except S11 (Dular, P80, TPR) which was placed in major group B showing great variation from all other isolates and group A consists of 6 minor groups in which minor group A6 was the largest containing 5 isolates i.e. Kasalath, P40, DSR (S13), Kasalath, P80, DSR (S14, S15, S16) & IR36, P40, DSR (S17).