The effect of Hbps on HemR-dependent heme uptake.

E. coli strains FB8.27 pBAD24, FB8.27 pBAD24::hbpA, FB8.27 pBAD24::hbpB, FB8.27 pBAD24::hbpC, FB8.27 pBAD24::hbpD, FB8.27 pAM239::hemR pBAD24, FB8.27 pAM239::hemR pBAD24::hbpA, FB8.27 pAM239::hemR pBAD24::hbpB, FB8.27 pAM239::hemR pBAD24::hbpC and FB8.27 pAM239::hemR pBAD24::hbpD were tested for efficiency of heme utilization as an iron source in iron-depleted medium M63 (Gly 0.4%, Ara 0.02%, Dip 80 µM, Spc, Amp).Growth around the wells containing 1 µM, 5 µM, 10 µM, or 50 µM Hb was as described in Materials and methods. After 48 h of growth, the diameter of the zone of turbidity aground the well was measured in quadruplicate for each plate and the mean diameter were calculated. Results are expressed as mean ± SD of the diameter (in cm) obtained for the three plates. NM: Not measurable.