Phosphate solubilizing bacteria promote growth and enhance nutrient uptake by wheat

Phosphorus (P) fixation limits availability of P to plants in tropical soil, which is a major constraint for crop production. The aim of our research was to isolate, screen and characterize phosphate solubilizing bacteria (PSB) from wheat and evaluate their efficacy in P nutrition in wheat. Upon screening, 9 isolates showing varying level of phosphate solubilizing activity in both agar plate and broth assays using Pikovskaya’s medium were obtained. The pH of the culture media was decreased with increased bacterial growth suggesting that they might secrete organic acids to solubilize insoluble phosphorus. In vitro wheat seedling bioassay with two superior PSB isolates (PSB1 and PSB8) and varying sources of P revealed that both isolates significantly enhanced seedling growth (shoot and root length, shoot and root dry weight) and nutrient contents (%N, %P and %K) in plant tissue compared to control (no PSB). The performance of PSB8 was superior to PSB1 in respect of all the parameters studied. The PSB8 was tentatively identified as Pseudomonas sp. through 16S rRNA gene sequencing. Our results suggest that Pseudomonas sp. PSB8 isolated from wheat might be useful for improving P nutrition in wheat in soils with low available P