Deficiency in ArgEF but not ArgB decreases extra- and intracellular siderophore production.

Siderophore production was quantified in 24 h liquid cultures representing iron starvation. For ΔargEF, ΔargB and their wt strains, the analysis was performed with 0.2, 1 and 5 mM arginine supplementation, respectively. ΔcpcA and its wt strain were analyzed without arginine supplementation. The data of mutant strains were normalized to that of the respective wt, in case of the ΔargEF and ΔargB mutants to the 5 mM arginine values. The data represent the mean of three biological replicates ± standard deviation.