Figure 2
Cell length measurement and determination of EGFP expression levels for recombinant Salmonella strains. (A) Cell length measurements for the eleven recombinant Salmonella strains. Each bar in the graph represents the mean length of 20 bacterial cells randomly selected from multiple microscopic fields for each strain, as measured using Image J software. Error bars show the standard deviation. An asterisk indicates that the mean length of the cells were significantly different from those of the SL7207 parent strain, as determined by Student T-test (P < 0.05). (B) Intensity of EGFP fluorescence emitted by each of the eleven recombinant Salmonella strains. SL7207 was included as a negative control. Measurements correspond to the average fluorescence emitted by 1 × 108 freshly-cultured bacterial cells (in 96-well micro-titer plates; excitation 488 nm, emission 518 nm); time resolved fluorescence of 500 ms. Bars in the graph represent the average fluorescence intensities from three independent experiments, ± standard deviation.