TABLE 1.

Capacities of B. abortus 2308, HR1703 (2308 bhuA), and HR1703RC (HR1703 bhuA⁺) to use hemin and FeCl₃ as iron sources

Strain	Diam (mm) of zone of bacterial growth witha:
	2 mM hemin	20 mM hemin	FeCl3
2308	22.3 ± 2.5b	32.7 ± 1.2d	52.7 ± 2.1
HR1703	NGc	NG	28.33 ± 1.3
HR1703RC	19.7 ± 1.5d	30.3 ± 1.5d	51.7 ± 3.8

^aThe diameters of the zones of bacterial growth on TSB supplemented with 300 μM EDDA around filter disks impregnated with 10 μl of a 2 mM solution of hemin, a 20 mM solution of hemin, or a 50 mM solution of FeCl₃ were measured after 96 h of incubation at 37°C with 5% CO₂. The values are the means ± standard deviations of the average zone sizes obtained from three separate experiments, and three separate determinations of growth were performed for each strain in each experiment.

^bP ≤ 0.01 for a comparison of HR1703 with 2308 and HR1703RC.

^cNG, no growth. No zone of bacterial growth was observed surrounding the disks impregnated with either concentration of hemin for B. abortus HR1703.

^dP ≤ 0.005 for a comparison of HR1703 with 2308 and HR1703RC.