Comparison of the physiological characteristics of <i>Bifidobacterium</i> in the different treatment groups.

<p>The same letters indicate no significant difference among the detected values (<i>p</i> > 0.05).Biological repeats, n = 6.</p

Schematic of the experimental design.

<p>Cultures in the mid-exponential phase (OD₆₀₀ = 0.6) were harvested and divided into two. Half of the cells were cultured for 2 h in the original medium, serving as the control group, and the other half of the cells wereculturedat pH 4.5 for 2 h, serving as the pre-stressed group. Then, the cells from both groups were harvested and challengedat a lethal pH 3.5 for 2 h. The resulting cells served as the control-pH 3.5 group and the pre-stressed-pH 3.5 group. ATR, response to pH 4.5; ASR, response to pH 3.5 of the cells in the control group; ASR, response to pH 3.5 of the cells in the pre-stressed group.</p

Protein-profiles of Bifidobacteriumlongum subsp. longum BBMN68 cells belonging to the different groups.

<p>A, control group; B, pre-stressed group; C, control-pH 3.5 group; D, pre-stressed-pH 3.5 group. Numbers indicate the protein spots of interest, for which information is listed in Table A in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0117702#pone.0117702.s001" target="_blank">S1 File</a>.</p

Effect of environmental pH on the intracellular pH in <i>Bifidobacterium</i>.

<p>White bars, the control cells; black bars, the pre-stressed cells. The same letters indicate no significant difference among the pH_in values in <i>B</i>. <i>longum</i>BBMN68 cells under different environmental conditions (<i>p</i>> 0.05). Biological repeats, n = 6.</p