Fig. 4

EHEC induced the locus of enterocyte effacement at the site of colonization. (A) Micrograph of Sakai wild-type (wt) EHEC::mCherry cotransformed with LEE1::gfp grown planktonically in E3 medium and zebrafish colonization by EHEC::mCherry/LEE1::gfp. Also see Movie S2 for a time-lapse presentation of the course of the infection shown in panel A. (B) Wild-type EHEC::mCherry cotransformed with promoterless control U9::gfp grown planktonically and zebrafish colonization by EHEC::mCherry cotransformed with U9::gfp. Zebrafish were exposed to 10⁸ CFU/ml of food-borne EHEC for 2 h. (C) EHEC Sakai isogenic ΔtolA mutant transformed with mCherry and LEE1::gfp grown planktonically and during zebrafish colonization. (D) EHEC Sakai isogenic ΔtolA mutant transformed with mCherry and promoterless U9::gfp grown planktonically and during zebrafish colonization. (E) Bacterial burden was determined by dilution plating on EHEC selective agar. Individual data points (n = 15 for each condition), means, and SD are shown. Statistical significance was determined using Student’s t test (***, P < 0.001). (F) Growth curves of the Sakai wild-type strain (blue) and the ΔtolA mutant (red). (G) Degradation profiles for the Sakai wild-type strain (blue) and the ΔtolA mutant (red) in P. caudatum as determined by lysis and dilution plating. Regression analysis showed that there is no difference between the slopes (P = 0.7016).