Morpho-molecular Characterization of Pseudomonas spp. Isolated from the Rice (Oryza sativa L.) Rhizosphere Across Tamil Nadu and Telangana, India

The rice rhizosphere harbors diverse antagonistic bacteria with significant potential for sustainable disease management. In the present study, twenty native Pseudomonas isolates were obtained from rice rhizosphere soils across major rice-growing regions of Tamil Nadu and Telangana, India, and evaluated through integrated morphological, biochemical, and molecular characterization. Considerable variability was observed among the isolates with respect to colony morphology, fluorescence under UV light, and key biochemical traits such as oxidase activity, nitrate reduction, siderophore production, phosphate solubilization, and citrate utilization, indicating functional diversity and ecological adaptability. Among the isolates, AUPS-10 exhibited superior phenotypic and biochemical attributes associated with antagonistic and plant growth–promoting potential. Molecular identification using 16S rRNA gene sequencing confirmed AUPS-10 as Pseudomonas fluorescens, which clustered closely with authenticated reference strains in phylogenetic analysis. The concordance between phenotypic traits and molecular confirmation highlights the reliability of the integrated approach used in this study. Overall, the findings emphasize the diversity of native antagonistic Pseudomonas spp. in rice rhizosphere soils and identify P. fluorescens AUPS-10 as a promising candidate for future biocontrol and sustainable rice production strategies.