Fig. 3.

Effect of pH (a), osmolarity (b), limitation of oxygen (c), and the presence of butyrate (d) on the expression of the tagged proteins. The tagged strains were grown in culture media at different pH (a), at various concentrations of NaCl (b), in the presence and limitation of oxygen (c), or in the absence and presence of 10 mM butyrate (d) as described in Methods. The values of the relative expression, which are the means±sd from triplicate experiments, represent the ratios of the level of the tagged protein under the experimental conditions to the control pH 7.0 condition (a), to the control condition of 170 mM NaCl of regular LB broth (b), to the control condition of the presence of oxygen (c), or to the control condition of the absence of butyrate (d). The analyses were repeated at least three times.