Globally, more than 99% of phosphate fertilizers are produced from phosphate rock stocks and traditionally use strong inorganic acids to produce more soluble forms of phosphate, generating by-products that impact the environment. This work investigated the effect of Bacillus megaterium and Pseudomonas fluorescens inoculation in nutrient broth medium (using initial pH 2 and submerged fermentation) in the phosphate solubilizing from ultrafine phosphate concentrate (35.7% of P2O5). It was obtained a solubilization of 28.88% and 54.89% for Bacillus megaterium and Pseudomonas fluorescens, respectively.