Using fluorescent microscopy with vital dyes we looked at the effect of the photo-catalytic reactor on E. coli cells.
The bacterial cells in E. coli suspension were stained with a Live/Dead BacLight bacterium viability kit (Molecular Probes, Netherlands) that contained SYTO 9 (live, fluoresces green) and propidium iodide (dead, fluoresces red).
As a result of difference of permeability between the stains, intact cells and damaged cells are visualized with green fluorescence or with red fluorescence, respectively. The bacterial cells in 25 viewing fields under fluorescence microscopy were randomly counted in each sample. The bacterial number counted by the culture method quickly decreased and reached the detection level after 10 min (Fig. 5a). The cells stained by the double staining method show either intact (green) or damaged cells (red) were observed as shown in Fig. 5b). The total number of bacterial cells containing
both intact and damaged cells counted by observation using microscopy did not decrease (Fig. 5a).
After 15 min, most cells seemed to be damaged (Fig.5c). At 10 min, even though the staining indicated intact cells detected by microcopy, they did not grow in culture.