4.4. IAA Extraction and Determination by Salkowski Reagent Method

IAA production and estimation was carried out following the method given by Gang et al. [46]. IAA biosynthesis in the cultures was induced by supplementing nutrient broth with 0.1% (w/v) L-tryptophan, and cultures were incubated in the dark at 30 °C on an orbital shaker at 200 rpm. IAA production and secretion were measured in culture supernatants after 24 h using Salkowski reagent. Briefly, 1 mL of culture supernatant was mixed with 1 mL of Salkowski reagent and incubated in the dark for 30 min. Development of pink color was spectrophotometrically measured at 536 nm and IAA quantified using an IAA standard.