Table 4 Plant growth-promoting traits of Azotobacter strains isolated in this study. Acetylene reduction assay was used to determine N2 fixation activity expressed as nmol ethylene h−1. Traits of cellulose degradation, lignin degradation, siderophore production, and phosphate solubiolization are expressed as a percentage of the total for each species
Species | Number of isolates | N2 fixation activity | IAA production (μg/ml) | Cellulose degradation | Lignin degradation | Siderophore production | Phosphate solubilization |
|---|---|---|---|---|---|---|---|
A. beijerinckii | 30 | 22.5±39.2 | 2.22±1.18 | 40.0 | 3.33 | 6.66 | 40.0 |
A. chroococcum | 50 | 22.8±30.2 | 3.05±1.62 | 26.0 | 22.0 | 86.0 | 22.0 |
A. tropicalis | 16 | 31.6±33.3 | 3.35±1.19 | 22.9 | 18.8 | 56.3 | 0 |
A. vinelandii | 2 | 13.4±14.1 | 2.12±0.71 | 0 | 0 | 100 | 50.0 |
Combined | 98 | 23.8±33.0 | 2.83±1.47 | 32.7 | 15.3 | 57.1 | 24.5 |