nitrogen fixation Efficiency of Azotobacter isolates under saline conditions


Azotobacter bacteria were isolated from different soil and rhizosphere samples with different electrical conductivities, from various regions of Basrah govemorate using nitrogen free sucrose medium and determined their ability to grow in various saline concentrations were 1%,2%,3%,4%,5%,6%,7%,8%,9%and10%,by adding NaCl salt to the nitrogen free medium.The isolates were streaked on the slanted medium and incubated at 28° c for three days. The efficiency of these isolates in nitrogen fixation was also measured in last saline medium when the isolate grown .The results showed that A24 isolate was able to grow at a salinity concentration of 10% .A5 and A22 were also grew in 9% concentration.A24 isolate was fixed the nitrogen in amount 7.42 and 5.46 mgN.L-1 at concentrations of 9% and 10% respectively ,while A5 and A22 isolate fixed 6.16 and 5.32 mg N.L-1 at saline concentration of 9% respectively.