Figure 1
From: Transcriptional activity around bacterial cell death reveals molecular biomarkers for cell viability
Effect of lethal temperature treatment. A) Temperature regime applied to exponentially growing B. subtilis cells. Duplicate samples were taken when the temperature reached 40, 50, 57, 58, 59, 60, and 62°C (indicated by black squares). Quenching of metabolic activity in the samples was performed by addition of cold methanol. B) Membrane integrity of B. subtilis. Heat-treated B. subtilis cell suspensions were directly labelled with propidium iodide, followed by flow-cytometric analysis. The fluorescence intensity per event of at least 10,000 cells per sample is shown as a histogram for each temperature treatment. C) Culturability versus membrane integrity. Colony forming units (CFU) of B. subtilis were determined after increasing periods of heat treatment (filled bars). In addition, the percentage of non-fluorescent cells after propidium iodide staining is indicated (open bars).