Selected bacterial cultures were grown for 48 h in liquid Czapek media. From 5% to 10% of this bacterial inoculum was transferred in 50-ml flasks to the 20 ml of the same media, supplemented with 200 μg ml−1 of DL-tryptophan (Sigma, USA). Cultivation was performed in the dark at 30 °C on a shaker (180 rpm) until the maximum of IAA concentration in the medium was reached