P236 - 612: ISOLATION OF N2 FIXING AND PHOSPHATE SOLUBILIZING RHIZOBACTERIA FROM DIFFERENT FIELDS IN KERMAN DISTRICT, IRAN

Background and Aim:Phosphorous is the most critical element for plant nutrition. Phosphate solubilization in soil can be achieved by using rhizobacteria with ability to enzymatic reactions such as phosphatase production or by soil acidification by acid production. Accordingly, in this study it is important to find new powerful phosphate solubilizing and nitrogen fixing rhizobacteria.Methods:Rhizospheric soil samples were randomly collected from different plants and immediately transferred to the lab by using ice box. About one gram of soil was poured into the bottle containing Thompson s medium. After shacking, it was placed horizontally and incubated for seven days at 30oC. Then, a streak plate was made on nitrogen free, iron free agar to obtain different colonies. An aliquot (10 μl) of each suspension with approximately 1×107 colony forming units/ml (CFU/ml) from a 2-day culture was spot inoculated on sperber agar. A clear zone around each spot during 1 week at 28oC was considered positive evidence of phosphate solubilization.Results:Twenty seven bacteria were isolated from soil samples. Nitrogen fixation abilities of all strains were confirmed by their growth on different nitrogen free media such as Ashby, Burk and jensen s media. On the other hand, nine isolates showed significant activities about phosphate solubilization and Their solubilization efficiencies (SE) were observed and calculated as 110.5,112.5,120.0,121.4,133.3,135.7,142.8, 166.6, 200.0.Conclusion:Isolated strain as IAUK7059 showed very promising results about nitrogen fixation and phosphate solubilization and it has a very good potential to be used in further experiments for biofertilizers construction.

کلیدواژه ها:

Rhizobacteria ، Phosphate Solubilization ، Nitrogen fixation ، PGPR ، In vitro screening