Figure 1.
(A) Comparative hemolytic activity of A. baumannii isolates in the presence of defibrinated sheep and horse red blood cells. NC = negative control (medium without bacteria), P.aeruginosa PAO1 = positive control showing hemolysis. The percent hemolysis in supernatant was measured at OD620 nm. Values represent the mean (± SD) of 3 independent experiments. (B) Quantification of siderophore in A. baumannii isolates in 3 different Fe concentrations. Values are expressed as percentage of siderophore units (U) normalized to the cell density OD600nm of bacterial culture. † = values are the means for a representative assay performed in triplicate. (C) Quantification of catechol groups in 3 different Fe concentrations. Presence of catechol groups in the supernatants of the A. baumannii isolates was detected by the Arnow test. Iron-chelating activity in culture supernatants of A. baumannii strains grown in Fe-limited medium showed with different color. A P ≤ 0.05 was considered as statistically significant for 2-tailed tests. (D and E) Effect of temperature on siderophore activity and pH on siderophore activity.