FIG. 5.

Hemin and hemoproteins induce expression from the bhuR promoter. B. avium 4169rif(pDJM41) was cultured in BHI broth supplemented with 100 μM EDDHA in combination with each of the following molecules: FeSO₄, hemin, turkey hemoglobin, myoglobin, catalase, or protoporphyrin IX. Each of the molecules was used at a concentration such that the total Fe concentration was 5 μM. β-Galactosidase activity was determined by using a modified version of the Miller assay (2, 27). The mean ± 1 standard deviation from the mean (indicated by the error bar) is shown for each value. Asterisks indicate the values that are significantly different (P < 0.05) from the value for EDDHA alone, as determined by the Student t test.