Vol. 9, Issue 5, Part I (2025)

Soil microorganisms play a vital role in nutrient cycling and plant growth by making essential nutrients like nitrogen, phosphorus and potassium bioavailable. This study aimed to isolate and characterize nitrogen fixing, phosphate and potassium solubilizing bacteria from the rhizosphere of onion plants in various districts of Maharashtra, India. Rhizospheric soil samples were collected and subjected to serial dilution and selective culturing using Jensen’s, Pikovskaya’s and Alexandrov’s media to isolate Azotobacter, Pseudomonas and Bacillus species respectively. The isolates were purified, maintained and characterized through morphological, cultural, Gram staining and biochemical tests. Results revealed diverse colony morphologies and biochemical profiles, identifying probable species such as Azotobacter sp., Pseudomonas sp. and Bacillus sp. These beneficial microbes have potential application as biofertilizers, offering an ecofriendly alternative to chemical fertilizers and contributing to sustainable agricultural practices.