TABLE 3.

Growth of wild-type and mutant S. thermophilus strains in TPPYC and in TPPYC supplemented with iron^a

Strain	Final OD600 resulting from growth in:
	TPPYC	TPPYC + FeSO4
Wild type	0.96	1.32
ΔsufD	0.58	1.48
iscU97	0.58	1.15

^aCells were grown in milk medium for 15 h at 42°C and diluted in FeSO₄-deficient medium (TPPYC medium supplemented with MgCl₂ [1 mM] and CaCl₂ [1 mM]). After 1 night of growth, cells were washed twice and resuspended either in FeSO₄-deficient medium or in medium supplemented with 100 μM FeSO₄. The growth of the cells was then followed by the measurement of the OD₆₀₀. The OD₆₀₀ was measured after 24 h of incubation at 42°C. This experiment was done in triplicate.