(C) Iron localization assay using atomic absorption spectroscopy. Two sets of bacterial cells were grown in iron-restricted media (PS + 150 μM DP) till late exponential phase. Cold iron (50 μM FeSO4) was added to the one set of bacterial cultures and incubated for one hour at 28°C. Bacterial cells were harvested, washed from the both sets of bacterial cultures. Periplasmic and cytoplasmic fractions were collected, freeze dried, and then iron content in each fraction was determined by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Iron content is represented on Y-axis as microgram of iron present per milligram of proteins in respective fractions. Data shown are mean ± S.E. (n = 3). * indicates p-value < 0.05 and ** indicates p-value < 0.01 by paired student t-test. 