As an approach to identify the iron depleted responsive protein, ITRAQ approach was used to analyze the supernatant of S. maltophilia strains [clinical (CS17) and environmental (LMG959)] grown in iron depleted condition. Appendix A and B lists the up-regulated proteins identified with ≥95% confidence including their respective ratio and peptides. A total of 480 and 358 proteins were identified in replicate 1 and replicate 2 which represent two independent analysis of the experiments for both strains that met the criteria of a minimum unused score cut of >1.3 which indicates >95% confidence in correct sequence identification. Figure 4 showed that 687 proteins were detected in which 151 proteins were commonly present in replicates, 329 and 207 proteins being unique to replicate 1 and replicate 2 respectively. From 687 proteins detected, a total of 122 proteins were seen with altered expression in response to iron depleted condition among both strains. Of these, 36 proteins upregulated and 7 down-regulated in LMG959 while for CS17, 60 proteins upregulated and 19 down-regulated (Appendix A).In another comparison, CS17 and LMG959 grown in normal condition were compared. ITRAQ identified 81 differently regulated proteins with 40 proteins up-regulated and 41 proteins down-regulated in CS17 when compared to LMG959 grown in normal condition.