Isolation and Characterization of Plant Growth Promoting Rhizobacteria from Agricultural Soils of North Telangana Region

Abstract

Background and Aims: Plant growth–promoting rhizobacteria (PGPR) constitute a diverse group of beneficial soil microorganisms that colonize the rhizosphere and enhance plant growth through multiple direct and indirect mechanisms, including nutrient mobilization and suppression of phytopathogens. In the present study, rhizospheric soil samples were collected from agricultural crop fields across four districts of North Telangana State to isolate and characterize potential PGPR strains. Methodology: Bacterial populations were isolated using the serial dilution technique, and aliquots (0.1 mL) of diluted soil suspensions were spread onto nutrient agar plates and incubated at 25–30 °C for 24–48 hours to ensure optimal bacterial growth. The isolated strains were subsequently screened on selective media for key plant growth–promoting traits, including phosphate solubilization, indole-3-acetic acid (IAA) production, hydrogen cyanide (HCN) production, and siderophore synthesis. Results: Among the isolates obtained, ten strains exhibited superior plant growth–promoting activities, however out of 10 bacterial isolates two isolates SP13 Brevudimonas diminuta, SP14 Acinetobacter baumannii were found to be most potential and novel strains and gives majority of the PGPR attributes, evidenced by prominent halo zones and clear inhibition zones surrounding the bacterial colonies. Conclusion: These promising isolates were preserved and further characterized based on colony morphology for future studies. Given their eco-friendly nature and potential to enhance crop productivity and soil fertility, the identified PGPR isolates demonstrate strong potential for development as biofertilizers suitable for the agro-climatic conditions of Telangana State.