TABLE 3.

Growth promotion by ferrichrome as sole iron source and sensitivity to antibiotics of cells expressing plasmid-encoded FhuAΔ5-160 or wild-type FhuAa

FhuA derivative on plasmidGrowthb of MB97 ΔfhuA/MB99 ΔfhuA tonB on ferrichrome at:Sensitivityb,c of MB97 ΔfhuA/MB99 ΔfhuA tonB to:
0.1 mM0.3 mM1 mM3 mMEry (15 μg; 734 Da)Rif (5 μg; 823 Da)Bac (30 μg; 1,421 Da)
Wild-type FhuA20/—24/—30/—35/—9/912/13—/—
FhuAΔ5-1608/—12/816/1520/1914/1518/1910
No FhuA—/——/——/——/—9/912/12—/—
  • a Growth promotion by ferrichrome and sensitivity to antibiotics was determined with E. coli MB97 ΔfhuA and MB99 ΔfhuA tonB expressing plasmid-encoded wild-type FhuA or FhuAΔ5-160. The growth zones with ferrichrome and the inhibition zones with antibiotics around filter paper disks that contained 10 μl of the various solutions with the indicated concentrations and amounts were determined.

  • b The size of the zones (in millimeters are given without subtraction of the paper disk (6 mm). —, no growth or no sensitivity.

  • c The molar masses of the inhibitors are indicated. Ery, erythromycin, Rif, rifamycin, Bac, bacitracin.