Isolation and screening of rhizobacteria for various plant growth promoting attributes

Plant growth promoting rhizobacteria (PGPR) are beneficial bacteria that colonize plant roots and enhance plant growth through a variety of mechanisms that include improvement of plant nutrition, production and regulation of phytohormones, and suppression of disease causing organisms. A total of ten morphologically different bacterial strains were isolated from rhizospheric soil of leguminous and non-leguminous crops and were evaluated for their various PGPR activities. Most of the strains were Pseudomonas and Bacillus species followed by Rhizobium, Mesorhizobium and Azotobacter species. The PGP traits studied were ammonia production, indole acetic acid (IAA) production, HCN production, potassium solubilization, phosphate solubilization, siderophore production and zinc solubilization. Interestingly, strain PGP2, PGP5, PGP7, PGP8, PGP9 and PGP10 seems to be very promising and can be potentially used to promote plant growth and sustainable agriculture.