Figure 4.

Survival of exponential-growth E. coli MG1655(pDRA) and MG1655 (pCTRL) cells grown on M9 media after 1 h exposure in acidified pH-2.5 M9 media. Cells were tested in M9 media supplemented either with 1.5 mM glutamate (gray bars) or without any glutamate (open bars). The difference in survival of E. coli MG1655(pDRA) in glutamate-supplemented versus nonsupplemented media is shown in the insert in a linear scale. Error bars indicate the standard error of at least three biological replicates, and statistical significance was tested with a two-sample t-test (*P < 0.05).