FIG 3.

Sialic acid can signal for increased ETX production. (A) (Top) Western blot showing ETX production by strain BMC202 grown for 4 h in MEM (no glucose or serum) in the presence or absence of the specified amounts of purified sialic acid (SA). The size of the immunoreactive protein, which matches the molecular mass of ETX, is indicated to the left. (Bottom) Relative band intensities of the Western blot compared by Image J analysis. The experiment was repeated three times, and mean band intensities are shown. The error bars indicate standard deviations. *, P < 0.005 compared to wild-type CN3718 strain by ordinary one-way ANOVA. (B) Comparison of the BMC202 culture OD₆₀₀ after a 4-h anaerobic incubation at 37°C in the presence or absence of sialic acid. Values are means ± standard deviations (error bars) for three repetitions.