Abstract:
Totally eighteen strains of bacterial with capable fix nitrogen and phosphate solubilize were isolated from various sources in nature. When analized nitrogen fixation by acethylene reduction technique and phosphate solubilization by colorimetric determination found that bacterial isolate M2 show the highest nitrogen fixing activity at 113.51 nmole/mg cell dry wt./hr. , N1 show highest phosphate solubilizing activity at 7.57 µg/ml and S54 show moderate both nitrogen fixing activity (50.05 nmole/mg cell dry wt./hr.) and phosphate solubilizing activity (5.90 µg/ml). These three bacterial strains were selected for further study. The effect of carbon sources, nitrogen sources, pH of media and incubation temperature on the efficiency of nitrogen fixation and phosphate solubilization of selected three of bacterial strains were study. The results revealed that all 3 bacterial isolates showed best efficiency of nitrogen fixing activity when cultured in nitrogen free medium supplemented with glucose as the carbon source with pH of media at 7 and incubated temperature at 30℃. And all 3 isolates showed best efficiency of phosphate solubilization when using ammoniumchloride as the nitrogen source and glucose as carbon source with pH of media at 5. The optimal temperature for phosphate solubilization of bacterial isolates N1 and S54 were at 30℃ while bacterial isolate M2 was at 40℃. From these studies we concluded that bacterial isolate N1 were the highest in both nitrogen fixing and phosphate solubilizing efficiency, due to that it grew well at broad conditions and had acid tolerance property. Bacterial isolate M2 later lost high efficiency at nitrogen fixing which might caused by mutation.