Hormone analysis
The extraction and purification processes were executed as described [18]. For hormone analysis, 5 mL of cold (−400 °C) 80% methanol was added to 5 mL bacterial culture suspensions. The bacterial suspensions were homogenized for 10 min using an IKA Ultra Turrax D125 Basic homogenizer, and then the bacterial suspensions were incubated for 24 h in the dark. The bacterial suspensions were filtered using a Whatman No: 1 filter, and the supernatants were filtered again using a 0.45 μm pore filter. The hormones were analyzed by HPLC using a Zorbax Eclipse-AAA C-18 column (Agilent 1200 HPLC), and the absorbance was read at 265 nm using a UV detector. Gibberellic acid, salicylic acid, indole acetic acid (IAA), and abscisic acid (ABA) were determined using 13% acetonitrile (pH 4.98) as the mobile phase.