Studying the Ability of some Bacteria Isolated from Egyptian Soils to Fix Nitrogen and Solubilize Phosphate, In Vitro

Abstract

Nitrogen and phosphorous are critical determinants for plant growth and productivity. Some soil bacteria can provide them in available forms to plants. These bacteria can be used as nitrogen fixers biofertilizers. In the current study, eighteen isolates of Azotobacter spp. were separated. The efficacy concentrations of the N2-fixation were examined using acetylene reduction technique, the isolates reduced acetylene at rates of 31.01 to 861.01 nmoles C2H4/ml/day. The highest lively isolate was No. AZ 14; recognized as Azotobacter beijerinckii. 8 phosphate-solubilizing bacteria (PSB) were insulated. These 8 P-solubilizing bacteria were analyzed for the tendency to solubilize P from tri-calcium phosphate in liquid Pikovskaya’s medium. The uppermost amount of free phosphorus in vigorously developing culture was 0.3652g g/100 ml after 28 days of cultivation and 0.1515g/100 ml after 7 days of cultivation on tri-calcium phosphate, correspondingly by isolate PSB 5 which was recognized as Bacillus paramycoides. Both nitrogen fixing bacteria and P-solubilizing bacteria isolates were genetically identified according to www. ncbi.nlm.nih.gov/blast data bank. The two isolates were defined according to standard morphological and biochemical tests as well as molecular tests.