Figure 5.

Qualitative detection of plant growth-promoting traits in the isolated P. polymyxa SK1. (a) Organic acid production was revealed by a color change to yellow in the upper well, while extreme lower well with pink color was used as a negative control. (b) Qualitative detection of IAA showing a change of coloration from yellow to pink. (c) IAA detection supplemented with various tryptophan concentrations. The tubes numbered with 1, 2, 3, and 4 show IAA detection at 0 mg·ml⁻¹, 2 mg·ml⁻¹, 4 mg·ml⁻¹, and 6 mg·ml⁻¹ tryptophan concentrations, respectively. (d) ACC deaminase activity. The upper well with brown coloration showed ACC deaminase detection while the lower well with yellow color was used as a negative control. (e) Production of siderophores was confirmed by a change of color from blue (−) to yellow/orange (+) as indicated by CAS assay.