Fig. 1.

A) Growth of the H. influenzae nontypeable strain 86-028NP and the hbpA insertion mutant strain HI2092 in hdBHI supplemented with heme as the sole heme source. Wild-type strain 86-028NP at 2 μg ml⁻¹ heme (solid circles), at 1 μg ml⁻¹ (solid triangles), and at 500 ng ml⁻¹ (solid squares). The hbpA insertion mutant strain HI12092 at 2 μg ml⁻¹ heme (open circles), at 1 μg ml⁻¹ (open triangles), and at 500 ng ml⁻¹ (open squares). B) Growth of the H. influenzae nontypeable strain 86-028NP and the hbpA insertion mutant strain HI2092 in hdBHI supplemented with hemoglobin, hemoglobin–haptoglobin, or heme–human serum albumin complexes as the sole heme source. Wild-type strain 86-028NP in heme–albumin 200 ng ml⁻¹ heme equivalent (solid circles), in hemoglobin 10 μg ml⁻¹ (solid squares), and in hemoglobin–haptoglobin 10 μg ml⁻¹ hemoglobin equivalent (solid triangles). The hbpA insertion mutant strain HI2092 in heme–albumin 200 ng ml⁻¹ heme equivalent (open circles), in hemoglobin 10 μg ml⁻¹ (open squares), and in hemoglobin–haptoglobin 10 μg ml⁻¹ hemoglobin equivalent (open triangles). Results are mean ± SD for quintuplicate results from representative experiments. The Kruskal-Wallis test was used to compare growth of 86-028NP and HI2092 in all heme sources at all heme concentrations p<0.0001.