Model depicting the x‐light system used for single bacterial analysis. Shigella flexneri M90T carry an inducible plasmid (x‐light Shigella) engineered with the LacI repressor system from Escherichia coli, and a GFP or mCherry gene downstream of the operator. In the presence of IPTG, metabolically active bacteria stop LacI repressor activity. As a consequence, the fluorescent protein is synthesised when bacteria are metabolically active.
HeLa cells were infected with x‐light Shigella‐mCherry for 4 h 40 min for quantitative confocal microscopy. IPTG was added 30 min prior to fixation, and then samples were labelled with antibody for SEPT7. The scale bar represents 5 μm. Graph represents mean % ± SEM of Shigella responding to IPTG outside (−) or inside (+) SEPT7 cages from four independent experiments. Student's t‐test, ***P < 0.001.
HeLa cells were infected with x‐light Shigella‐mCherry for 4 h 40 min for quantitative confocal microscopy. IPTG was added 30 min prior to fixation, and then samples were labelled with antibody for p62. The scale bar represents 5 μm. Graph represents mean % ± SEM of Shigella responding to IPTG without (−) or with (+) p62 from at least four independent experiments. Student's t‐test, ***P < 0.001.
Control (CTRL) or isopropanol‐treated x‐light Shigella‐GFP were induced with IPTG for 30 min and then labelled with SYTOX Orange for 10 min. The scale bar represents 5 μm.
HeLa cells were infected for 2 h 10 min, treated with ethanol (CTRL) or erythromycin (EM) for 2 h prior to fixation and then labelled with antibody for SEPT7. Graph represents mean % ± SEM of Shigella in SEPT7 cages from three independent experiments. Student's t‐test, ***P < 0.001.