Phosphate solubilization potential of PSB: An advance approach to enhance phosphorous availability for phytostimulation

Abstract Rhizosphere engineering approach is considered a quantum leap in plant sciences. The current study focused on investigating rhizobacterial efficiency to mobilize bioavailable phosphate from insoluble-phosphate source. Phosphate-solubilization potential of four efficient phosphate solubilizing bacterial strains i.e., Pseudomonas songnenensis (GR3), Stutzerimonas stutzeri (HH2), Bacillus bingmayongensis (KH3) and Achromobacter aegrifaciens (MH1) was analyzed. The bacterial strain GR3 was observed as most efficient phosphate solubilizer. Interactions between various physiological parameters and phosphate solubilization efficiency of isolates was evaluated using surface response methodology. In-vitro experiments revealed that glucose significantly facilitated phosphorus solubilization at 37 ℃, with media having pH 7 and 0.5% phosphorous. Additionally, positive correlation among P-solubilization potential, acids produced and pH variations was observed. Plant microbe-interaction analysis was performed to evaluate the efficiency of these bacterial strains on various morpho-physiological responses of Zea mays L. For this purpose, various concentrations of tricalcium phosphate were applied to plants in the presence and absence of bacterial strains. The results showed that, lower phosphate levels trigger shoot development, improve plant weight and leaf formation whereas higher phosphate concentrations stimulated the development of longer root system. The bacterial strains GR3 and HH2 were observed as efficient phosphate-solubilizing bacteria (PSB) that positively stimulated plant morphological responses by triggering various biochemical attributes such as plant protein content, phytohormone homeostasis, macromolecule content, solute content and pigment content. Hence, the current study reviled that the use of these phosphate solubilizing PGPR are efficient phytostimulators used for crop production in replacement of chemical fertilizers which are carcinogenic and deteriorating our eco-system.