Figure 3.

EstA enhances the nutrative potential of mucin during community-driven foraging. E. coli MG1655 was grown in M63 minimal medium supplemented with bovine submaxillary mucin in the presence of different enzyme combinations as described under “Experimental procedures.” A, growth was monitored by optical density (600 nm) readings taken every 2 min using a Tecan M200 plate reader. B, E. coli depletion of mucin sialic acids was examined by measuring total Neu5Ac levels in spent media at the end of the growth experiment. ANOVA with Dunnett's post test was used to examine statistical significance compared with medium alone and E. coli alone controls: different from media alone (a, black bar), p < 0.05; different from E. coli, no enzymes (b, gray bars). One-way ANOVA followed by pairwise t tests adjusted for multiple comparisons by the Bonferroni method was used to further evaluate differences between growth under conditions with sialidase alone versus sialidase + EstA. *, p < 0.05. This experiment was performed once with one biological replicate and one technical replicate and once with three biological replicates with one technical replicate each. It was also done as end-point assays in culture tubes, wherein only initial and final optical density measurements were taken. Bt, red, B. thetaiotaomicron; Bf, blue, B. fragilis.