Screening of Azotobacter isolates for PGP properties and antifungal activity
2015
Bjelić, Dragana Đ. (Institute of Field and Vegetable Crops, Novi Sad (Serbia)) | Marinković, Jelena B. (Institute of Field and Vegetable Crops, Novi Sad (Serbia)) | Tintor, Branislava B. (Institute of Field and Vegetable Crops, Novi Sad (Serbia)) | Tančić, Sonja Lj. (Institute of Field and Vegetable Crops, Novi Sad (Serbia)) | Nastasić, Aleksandra M. (Institute of Field and Vegetable Crops, Novi Sad (Serbia)) | Mrkovački, Nastasija B. (Institute of Field and Vegetable Crops, Novi Sad (Serbia))
Аmong 50 bacterial isolates obtained from maize rhizospherе, 13 isolates belonged to the genus Azotobacter. Isolates were biochemically characterized and estimated for pH and halo tolerance ability and antibiotic resistance. According to characterization, the six representative isolates were selected and further screened in vitro for plant growth promoting properties: production of indole-3-acetic acid (IAA), siderophores, hydrogen cyanide (HCN), exopolysaccharides, phosphate solubilization and antifungal activity (vs. Helminthosporium sp., Macrophomina sp., Fusarium sp.). Beside HCN production, PGP properties were detected for all isolates except Azt 7 . All isolates produced IAA in the medium without L-tryptophan and the amount of produced IAA increased with concentration of precursor in medium. The highest amount of IAA was produced by isolates Azt 4 (37.69 and 45.86 µg ml -1) and Azt 5 (29.44 and 50.38 µg ml -1) in the medium with addition of L-tryptophan (2.5 and 5 mM). The isolates showed the highest antifungal activity against Helminthosporium sp. and the smallest antagonistic effect on Macrophomina sp. Radial Growth Inhibition (RGI) obtained by the confrontation of isolates with tested phytopathogenic fungi, ranged from 10 to 48%.
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