Screening and Characterization of High Efficiency Phosphate Solubilizing Bacteria from the Rhizospheres of Sangareddy District, Telangana, India

Abstract

This study investigated the potential of indigenous phosphate-solubilizing bacteria (PSB) to address phosphorus limitation in the semi-arid tropical soils of Sangareddy district of Telangana state. By isolating microbial strains from diverse rhizospheric environments and employing both qualitative and quantitative characterization—including the molybdenum blue method and multi-phasic biochemical analysis—we identified ten high-performing isolates from the Pseudomonas, Bacillus, and Micrococcus genera. A notable discrepancy was observed between solid-media halo zones and liquid-broth efficiency, confirming the "Nautiyal effect" and highlighting that acid diffusion rates in solid media may underestimate true phosphate solubilizing metabolic potential. Specifically, Isolate I47 (Pseudomonas strain) demonstrated an exceptional quantitative solubilization capacity, marking it as a superior candidate for agricultural application. These resilient, locally adapted bacteria represent a promising biological toolkit for developing cost-effective bio-fertilizers. By enhancing the bioavailability of mineral-locked phosphorus, these isolates offer a sustainable strategy to improve soil fertility and increase crop productivity in phosphorus-fixing tropical ecosystems.