Siderophore production
Yeast culture grown on YPD agar at 28 ± 2 °C for 24 h was used as inoculum, which was point inoculated onto chrome azurol S (CAS) agar (Schwyn & Neilands 1987). The cultures were incubated at 28 ± 2 °C for 5 d. Isolates showing colonies surrounded by orange zones were considered siderophore-producing isolates.