Two phosphate-solubilizing bacterial strains were isolated and identified as Acinetobacter calcoaceticus YC-5a and Enterobacter agglomerans KMC-7 based on the 16S rRNA gene sequence analysis. A.calcoaceticus YC-5a is less well known as phosphate solubilizing plant-associated bacteria. In this study, both A.calcoaceticus YC-5a and E. agglomerans KMC-7 produced multiple organic acids followed by a decrease in the pH of the culture medium there by solubilizing the insoluble tricalcium phosphate. The soluble phosphate production of these two strains in NBRIP medium were 518.2±17.3 mg l-1 and 435.4±15.6 mg l-1, respectively. Inoculation with these two isolates were observed to significantly (p<0.05) increase the stem diameter and shoot dry weight compared to the uninoculated control. And A.calcoaceticus YC-5a showed better than E. agglomerans KMC-7 in phosphate solubilizing and plant growth promoting, though E. agglomerans KMC-7 was found to produce indole acetic acid and siderophore. The results of the study revealed that the inoculation of PSB promotes plant growth mainly by phosphate solubilizing activity, and indirectly by plant growth regulators.