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. 2008 Oct 13;76(12):5598–5607. doi: 10.1128/IAI.01180-08

FIG. 3.

FIG. 3.

Analysis of type 1 fimbria expression by STEC O157 strains. (A) PCR analysis of the fim switch deletion using STEC O157:H7-specific primers. NSF STEC O157:H7 strains EDL933, H77, H511, and 1477/AI (lanes 1 to 4, respectively) generate a 943-bp product indicating the presence of the deletion that is absent in the SF STEC O157:NM strains H2687, H8824, H8432, H8489, H8757, and H8478 (lanes 5 to 10, respectively). Lane 11 contains a DNA-negative control, and lane M contains a 100-bp molecular size marker. (B and C) PCR and restriction digestion of the fim switch from isolates indicating the expression status within the bacterial population. (B) The isolates were cultured under conditions optimal for type 1 fimbria expression (3-day subculture in LB broth, statically at 37°C). The results of the yeast cell agglutination assay are summarized below the gel image. The fim switch was detected in both the on and off orientations for the two SF STEC O157:NM strains examined (H2687 and H8824, lanes 3 and 4, respectively) but only in the off orientation for the two NSF STEC O157:H7 strains analyzed (EDL933 and 1477/AI, lanes 1 and 2, respectively). (C) When cultured on CFA agar plates, the fim switch in the on orientation was only detected in one SF STEC O157:NM strain (H2687, lane 3) but not H8824 (lane 4) or the two NSF STEC O157:H7 strains (EDL933 and 1477/AI, lanes 1 and 2, respectively). Lane M contains a 100-bp molecular size marker.