LIVE/DEAD Cell Viability Assays

LIVE/DEAD kits for bacterial viability are convenient and easy-to-use 2-color fluorescent assays to discriminate between live and dead bacterial cell populations based on membrane integrity.

Learn more about these LIVE/DEAD bacterial viability kits.

LIVE/DEAD kits for bacterial viability are convenient and easy-to-use 2-color fluorescent assays to discriminate between live and dead bacterial cell populations based on membrane integrity. These kits contain SYTO 9 green-fluorescent stain and PI red-fluorescent stain that differ in their ability to enter bacteria. When used alone, SYTO 9 will stain all bacteria in a population regardless of membrane integrity; however, PI will only enter bacteria with a compromised membrane causing reduced SYTO 9 fluorescence. With an optimized mixture, dead bacteria will fluoresce red, while live bacteria will fluoresce green. These assays have been optimized for use on fluorescence microscopy (Figure 3), flow cytometry (Figure 4), and microplate readers.

Learn more: bacterial viability assays for flow cytometry

Figure 4. Analysis of bacterial cultures using the LIVE/DEAD BacLight Bacterial Viability and Counting Kit. Suspensions of live (untreated) and dead (alcohol-treated) Staphylococcus aureus (Panels A and C) and Escherichia coli (Panels B and D) were stained and analyzed by flow cytometry according to the LIVE/DEAD BacLight Bacterial Viability and Counting Kit protocol. Using green or red fluorescence versus side scatter cytogram (Panels A and B), the bacterial populations and the bead populations were gated (left and right boxes, respectively). Events in the bacteria region of each cytogram are also displayed in red fluorescence versus green fluorescence cytograms (Panels C and D). Live and dead bacteria/mL can be calculated from either the fluorescence versus side scatter cytogram or the green fluorescence versus red fluorescence cytogram, depending on which one shows the best separation of the live and dead populations. The position of the live and dead populations in these cytograms may be dependent on cell type and gram character. Some samples may exhibit events that fall outside the defined regions and should be evaluated appropriately (e.g., see Panel D).

LIVE/DEAD kits for fungi and yeast viability offer 2-color discrimination of live and dead fungal populations based on membrane integrity or metabolic activity and fungal cell wall labeling.

Learn more about these LIVE/DEAD fungi and yeast viability kits.

LIVE/DEAD Yeast Viability Kits provide easy, reliable, and quantitative discrimination in pure or mixed cultures. Each kit offers 2-color discrimination based on membrane integrity or metabolic activity, and fungal cell wall labeling.

Learn more: yeast viability assays for flow cytometry

The Yeast Viability Kit (Figure 5) contains FUN 1 dye, that uses the plasma membrane integrity and metabolic activity of live populations to convert the yellow-green-fluorescent intracellular staining to red-orange intravacuolar structures, and Calcofluor White M2R which labels cell-wall chitin with a blue-fluorescence.

The LIVE/DEAD FungaLight Yeast Viability Kit uses 2 nucleic acids stains - SYTO9 green-fluorescent stain and PI red-fluorescent stain (Figure 6). When used alone, SYTO 9 will stain all yeast in the population; while PI only enters yeast with a damaged membrane resulting in reduced SYTO 9 fluorescence. As a result, live yeast with uncompromised membrane will fluoresce green whereas dead yeast with compromised membrane will fluoresce red.

Figure 6. Saccharomyces spp. cell suspensions stained with SYTO 9 dye and propidium iodide and analyzed using a BD FACSCalibur flow cytometry system (Becton Dickinson and Co.). Panel A shows the dot plot of forward scatter vs. side scatter of an untreated Saccharomyces culture, washed and stained with SYTO 9 dye and propidium iodide as described in the LIVE/DEAD FungaLight Yeast Viability Kit protocol. The region R1 contains particles of the appropriate size for yeast cells; the forward scatter trigger is set to exclude debris in the sample. Panel B shows the R1-gated staining pattern obtained following analysis of a sample of yeast containing a mixture of both live and heat-killed cells.