FIG. 3.
Relative survival of acid challenge at pH 2.75 for 2 h. Isogenic deletion strains (Δ; open columns) were compared to wild-type E. coli strain MG1655. Strains overexpressing cloned genes (p indicates gene overexpression; shaded columns) were compared to E. coli MG1655 (pPCRScriptAmp). Increased survival compared to the controls is indicated by positive values, and decreased survival is indicated by negative values. Each value reported is the mean of at least nine replicates, and the standard deviations are indicated by error bars.