Single-staining flow cytometry approach using SYTOXTM green to describe electroporation effects on Escherichia coli

Pulsed electric fields (PEF) can induce reversible or irreversible electroporation effects on bacterial cells resulting in sublethally or lethally injured cells. Hereafter, an alternative single-staining flow cytometry approach with SYTOXTM Green (SYTOX) is proposed, allowing for a straightforward and rapid screening of electroporation effects. SYTOX-staining indicated 38-63% of E. coli cells with intermediate cellular changes, likely being sublethally injured, at electric field intensities of 8 kV/cm-18 kV/cm. Compared to staining with propidium iodide, SYTOX showed a brighter fluorescence intensity, allowing for easier differentiation of subpopulations. The proportion of intermediate injury observed with SYTOX was distinctly higher than the sublethal damage detected with conventional plating on selective media (31-45%). It is, however, challenging to compare selective plating with the single-staining method based on membrane integrity, suggesting different analytical methods to indicate complex cellular states and sublethal effects.

Automated summary

The use of SYTOX staining in flow cytometry allows for more accurate screening of bacterial cells affected by electroporation effects, showing brighter fluorescence intensity than traditional staining methods. However, the proportion of sublethal damage observed with SYTOX was higher compared to traditional plating methods, suggesting that selective staining methods may be more challenging.