Fig. 3

C-di-AMP enhances the expression of fliC and elongates the flagellin in both non-AIEC K12 and AIEC LF82 strains. A The expression levels of fliC in the non-AIEC K12 and AIEC LF82 strains, which were cultured in the presence of 5.0 μM c-di-AMP for 16 h, were analyzed using quantitative real-time PCR. Data are presented as the mean ± SD. *P < 0.05, **P < 0.01; P-values were determined using the unpaired Student’s t-test. (n = 4 each). B Morphological changes in non-AIEC K12 and AIEC LF82 strains cultured in the presence of 5.0 μM c-di-AMP for 16 h were visualized using scanning electron microscopy (SEM). Each image is representative of different bacterial areas (n = 4 each). C Length of flagellin filaments measured using SEM images. SEM images were imported into the ImageJ software, and the flagellin length per bacterial cell was measured. Data are presented as the mean ± SD. *P < 0.05; P-values were determined using the student’s t-test. Scale bar = 2.0 μm