## 2 Materials and Methods
### Screening for Other Plant-Growth Promoting Traits  
The production of IAA was analyzed colorimetrically [44]. In brief, 70 \(\upmu\)L of supernatant obtained from cultures grown in TSB supplemented with 1% L-tryptophan (Alfa Aesar, Karlsruhe, Germany) was mixed with 140 \(\upmu\)L of Salper solution (2 mL 0.5 M FeCl\({}_{3}\) in 98 mL of 35% HCLO4) in microplate wells (4 replicates). The mixture was incubated in the dark for 30 min for color development, and OD535 was determined. Standard solutions of commercial IAA (Loba Chemie Pvt, Ltd.) were used to construct a calibration curve for the interpolation of results. An environmental strain of _Pseudomonas aeruginosa_[45] was included as positive control. ACC-deaminase activity was determined as the ability to use ACC as a sole nitrogen source with production of \(\alpha\)-ketobutyrate. Isolates grew in DF (Dworkin and Foster) minimal salt medium, containing KH\({}_{2}\)PO\({}_{4}\) (4 g L\({}^{-1}\)), Na\({}_{2}\)HPO\({}_{4}\) (6 g L\({}^{-1}\)), MgSO\({}_{4}\cdot\)7H\({}_{2}\)O (0.2 g L\({}^{-1}\)), glucose (2 g L\({}^{-1}\)), FeSO\({}_{4}\cdot\)7H\({}_{2}\)O (1 mg L\({}^{-1}\)), H\({}_{3}\)BO\({}_{3}\) (10 \(\upmu\) L\({}^{-1}\)), MnSO\({}_{4}\) (10 \(\upmu\) L\({}^{-1}\)), ZnSO\({}_{4}\) (70 \(\upmu\) L\({}^{-1}\)), CuSO\({}_{4}\) (50 \(\upmu\) L\({}^{-1}\)), MoO\({}_{3}\) (10 \(\upmu\) L\({}^{-1}\)), and agar (15 g L\({}^{-1}\)), with pH 7.2. This medium was supplemented with either (NH\({}_{4}\))\({}_{2}\)SO\({}_{4}\) (2 g L\({}^{-1}\)) or 3 mM ACC (Alfa Aesar, Karlsruhe, Germany) or received no supplementation. Overnight cultures in DF supplemented with (NH\({}_{4}\))\({}_{2}\)SO\({}_{4}\) were spotted on DF minimal salts agar, non-supplemented or supplemented either nitrogen sources to determine presumptive positive isolates. Cultures were incubated at 30 \(\pm\) 2 \({}^{\circ}\)C for 3 days, and growth was checked daily for detection of ACC deaminase activity. A colorimetrical method, using cultures grown in liquid DF medium supplemented with 3 mM ACC, was used for the quantitative analyses of ACC deaminase activity, expressed as the amount of \(\alpha\)-ketobutyrate produced [46; 47]. The OD540 of a sample was compared with that of a standard curve constructed with 0.1 to 1.0 mmol solutions of alpha-ketobutyrate (Sigma-Aldrich, St. Louis, MO, USA). DF medium without supplementation was used as negative control. For each test, 3 replicates were used. Siderophore production was detected in TSA, deferrated by the addition of 50 \(\upmu\)M 2-2'dipyridyl [48]. After incubation, the plates displaying bacterial growth were overlaid with Chrome Azurol S reagent (CAS, MB Biomedicals, LLC) and incubated for 2 h. Siderophore production was detected as a change of color of the overlay from blue to orange, yellow or purple [49]. The test was conducted in triplicate. Phosphate solubilization was detected by cultivation in SRSM1 broth [50]. Presumptive phosphate solubilization was inferred from the change of color of the medium from purple to yellow, as the result of acidification. Positive results were confirmed by development of a clear halo formed around colonies in Pikovskaya medium, after 24 h incubation at 30 \({}^{\circ}\)C. _Pseudomonas aeruginosa_[51] and _Bacillus cereus_[52] were used as positive controls. Two independent assays with 3 replicates each were conducted. For the detection of nitrogen-fixation ability, isolates were inoculated in a semi-solid medium containing glucose (10 g L\({}^{-1}\)), malate (10 g L\({}^{-1}\)), K\({}_{2}\)HPO\({}_{4}\) (1 g L\({}^{-1}\)), CaCl\({}_{2}\) (0.1 g L\({}^{-1}\)), MgSO\({}_{4}\cdot\)7H\({}_{2}\)O (0.2 g L\({}^{-1}\)), FeSO\({}_{4}\cdot\)7H\({}_{2}\)O (0.01 g L\({}^{-1}\)), Na\({}_{2}\)MoO\({}_{4}\cdot\)2H\({}_{2}\)O (0.01 g L\({}^{-1}\)), MnSO\({}_{4}\cdot\)5H\({}_{2}\)O (0.01 g L\({}^{-1}\)), NaCl (25 g L\({}^{-1}\)), agar (5 g L\({}^{-1}\)) and trace bromothymol blue [53]. Nitrogen fixation was presumptively detected by the change of color of the medium from green to blue.