Screening of Azotobacter isolates for PGP properties and antifungal activity

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 Azt7. 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 Azt4 (37.69 and 45.86 μg ml-1) and Azt5 (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%. [Projekat Ministarstva nauke Republike Srbije, br. TR 31073]

Abstract licence: CC BY-NC-ND

• Nitrogen Fixing Azotobacter Species as Potential Soil Biological Enhancers for Crop Nutrition and Yield Stability · 2021

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