Nitrogen (N), Phosphorus (P) and Potassium (K) are the major essential macro-nutrients for plants. The ability of soil bacteria to provide available forms of these nutrients to plants is an important feature in the bacterial strain used as a bio-fertilizer. In this study, fifteen isolates of Azotobacter spp were isolated. The efficiency levels of the N₂-fixation were tested, the isolates reduced acetylene at rates of 6.348 - 1381.023 nmoles C₂H₄/ml/day. The most active isolate was No. AZ 8 that identified as Azotobacter chroococcum MF135558. Twenty-one phosphate-solubilizing bacteria (PSB) were isolated and solubilization efficiency % (SE%) of each isolate was determined by spot inoculation technique. Five isolates (PSB 3, PSB 7, PSB 8, PSB 12 and PSB 14) were chosen due to their high solubilization efficiency % (SE%) 182.35, 173.33, 222.22, 170.00 and 194.11 %, respectively. The five P-solubilizing bacteria were tested for their ability to solubilize P from tri-calcium phosphate and rock phosphate in liquid Pikovskaya's medium. The highest quantity of released phosphorus in actively growing culture was 36.52 mg/100 ml after 28 days of incubation and 1.095 mg/100 ml after 3 days of incubation on tri-calcium phosphate and rock phosphate, respectively by isolate PSB 14 which was identified as Klebsiella oxytoca MF135559. Five isolates of K-releasing bacteria (KRB) were isolated on Alexandroov's medium and were tested to release K from mica-muscovite. All the tested isolates can release potassium from mica but not in equal efficiency. The most efficient isolate namely KRB-2 could release 7.05 ppm after 6 weeks of incubation. It was identified as Rhizobium pusense MF135560.