Figure 4.

(A) Iron uptake. Cell-associated counts were corrected for cell number, as measured by OD₆₀₀, and normalized to control values. Therefore, small negative uptake numbers are possible for strains with no activity over the vector-only control. All assays were done in quadruplicate; the values and error bars are the mean and standard error, respectively. This experiment was performed four times; a representative data set is shown. (B) Zinc uptake. Values were determined as in A except that this experiment was performed three times; a representative data set is shown.