Fig. 1

Identification of siderophore types and crude extraction of siderophore from ZS-3 fermentation filtrate; (A) hydroxamic acid type was detected by FeCl₃ experiment; (B) Tetrazolium salt test to detect hydroxamic acid type; (C) Color reaction of 40 µL 100-fold P. megaterium ZS-3 siderophore crude extract cultured overnight in CAS plate under darkness