FIG. 3.

Addition of either iron or manganese to L broth containing EDDA restores growth of the S. flexneri sitA mntH mutant to wild-type levels. Overnight cultures of S. flexneri SM100 (wild type) and UR003 (sit::cam mntH::kan) were subcultured 1:1,000 into L broth with (+) or without (−) 350 μM EDDA, 350 μM ferric chloride (F), or 350 μM manganese chloride (M) as indicated. After 12 h of growth at 37°C, the number of bacteria per milliliter of culture was determined by viable plate counts. The data presented are the means of three experiments, and the standard errors of the means (error bars) are indicated.