Evaluation of multiple plant growth promoting traits of an isolate of Pseudomonas fluorescens strain Psd

P. fluorescens strain Psd was isolated from the rhizosphere of Vigna mango and evaluated for its multiple plant growth promoting and biocontrol properties against F. oxysporum. Interestingly, this strain not only produces a range of antimicrobial compounds but also solubilizes complexed phosphates and synthesizes phytohormone (IAA). These properties can be assessed to elucidate the agronomic significance and rhizospheric competence of this soil isolate. Biocontrol action has been demonstrated in vitro against some other rhizospheric bacteria, and a phytopathogenic fungus along with wild type E. coli K-12. Genetic evidence for the antimicrobial status of strain Psd has been derived in terms of elucidating a unique combination of phenazine and pyrrolnitrin biosynthesis genes, not reported for any other P. fluorescens strain. The conserved part of antibiotics biosynthesis operon has been PCR amplified, cloned, sequenced and phylogenetic relationship based on similar genes from a few known Pseudomonads has been derived. The properties possessed by strain Psd may enable the bacterium to establish itself successfully in the rhizosphere.