Siderophore Production Screening in Bacteria

The methods of Schwyn and Neilands [32 (link)] were employed to determine the siderophore production of each bacterial isolate in a chrome-azurol S (CAS) medium composed of 10 mL of an Fe(III) solution (27 mg of FeCl₃·6H₂O and 83.3 µL of concentrated HCl in 100 mL of ddH₂O) along with 72.9 mg of hexadecyltrimethyl ammonium bromide (HDTMA). Each fresh bacterial culture 24 h old on nutrient agar was aseptically picked with a sterilized inoculating loop and streaked on the sterilized chrome-azurol S (CAS) medium and incubated for 48–72 h at 37 °C. The appearance of yellow/orange coloration around the colonies implied siderophore production.