Figure 6

Comparison of excitation and emission spectra of ampicillin-treated E. coli cells and purified flavonoid compounds. E. coli 7705035 cells [MIC = 4 mg/L] growing exponentially in M9 medium supplemented with glucose, were treated with a range of ampicillin concentrations for 6 hours. After 6 hours of treatment, the excitation and emission spectra of treated cells were established and compared with the spectra of FAD, FMN and riboflavin. Three-dimensional representation of fluorescence spectra of flavins (a) and E. coli (b). (c) and (e): excitation and emission spectra of E. coli cells treated with ampicillin, normalized to the optical density at 600 nm. The colors represent ampicillin concentrations: 0 (blue line), 1 (violet line), 4 (red line), 8 (yellow line) and 32 mg/L (green line). (d) and (f): excitation and emission spectra of 10 µM purified flavonoid compounds: FAD, FMN and riboflavin. The colors represent: light grey for FAD, black for FMN and dark grey for riboflavin. This figure presents results of representative experiments, which were independently repeated 4 times.