Phosphate solubilizing activity of Pseudomonas fluorescens PSM1 isolated from wheat rhizosphere
A study was designed to screen and analyze the efficient phosphate solubilizing bacteria (PSBs) from wheat rhizosphere. Five biovars of Pseudomonas fluorescens (PSM1, PSM2, PSM3, PSM4 and PSM5) were isolated from wheat rhizosphere and Bacillus megaterium MTCC 8755 procured from microbial type culture collection (MTCC) Chandigarh, India. The P. fluorescens biovar PSM1 was observed to be most efficient phosphate solubilizer. Inoculation of P. fluorescens PSM1 and B. megaterium MTCC 8755, alone and in combination, caused the highest phosphate solubilization at pH 5. At this pH, maximum phosphate solubilization was observed with B. megaterium MTCC 8755 inoculation (8.2 mg mL-1) on sixth day of incubation with P. fluorescens PSM1 (8 mg mL-1) on seventh day of incubation and with dual bacterial treatment (10.5 mg mL-1) on the fourth day of incubation. A correlation coefficient of linear regression equation of phosphate solubilization with pH indicated that pH value of the medium was directly correlated with tricalcium phosphate solubilization. The study will help in choosing soil pH specific PSB inoculant for optimizing plant growth.