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

Abstract

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 SYTOX™ 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.