Figure 5

Effects of deleting gcvB on acid resistance in mutants lacking hns , crp or gadX. Cell cultures of E. coli MG1655 mutant strains containing single deletions of the hns, crp or gadX genes were grown in LB broth (pH 7.0) at 37°C for 5 hrs and then acid challenged (pH 2.0) for 15 min (gadX mutant) or 30 min (hns and crp mutants). After neutralization by adding alkalinized LB (pH 9.3), cells were cultured for an additional 3 hrs before measurement of optical density at 600 nm (OD600 nm). Error bars represent standard deviation (* P-value < 0.05).