Fig. 4

Fluorescence microscopy of DAPI- and SYTOX Green-labeled bacteria. Three kinds of the engineered E. coli strains (PGETS118-DE, BUT1-DE and BUT3-DE) were cultured in PYG medium and incubated at 37 °C for 48 h. All bacteria were stained with both DAPI and SYTOX Green nucleic acid stains. The staining patterns of E. coli labeled with 1 μg/ml DAPI and 5 μM SYTOX Green were compared via fluorescence microscopy. Viable bacteria or membrane-intact cells were stained and appear blue only (a, d). Nonviable bacteria or membrane-damaged cells are stained and appear blue and green (b, e and c, f). Scale bar = 5 μm. Measurements were obtained from three replicate experiments