LIVE/DEAD™ BacLight™ Bacterial Viability Kit, 10 Applicator Sets kit - FAQs

View additional product information for LIVE/DEAD™ BacLight™ Bacterial Viability Kits - FAQs (L7007, L13152, L7012)

6 product FAQs found

When using the LIVE/DEAD BacLight kit for bacterial viability, with SYTO 9 and propidium iodide (PI), why are some cells detected with both dyes? Shouldn't live cells be green and dead cells be red?

SYTO 9 dye will enter all cells, live or dead. PI only enters cells with compromised membranes (dead cells or damaged cells). First, perform single color staining and examine under both filter sets. Longpass filters or the use of too much dye may result in excessive bleedthrough of the green dye emission into the red channel and the emission of PI in the green channel. Use narrower bandpass filters if possible, and use lower concentrations of the dye. Some live cells may take up PI by engulfment; avoid extended incubation times with the dye. Apply PI to a live cell culture and optimize incubation times to limit engulfment.

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I want to use propidium iodide and SYTO 9 to do LIVE/DEAD testing of a bacterial sample. Will anaerobic conditions adversely affect the assay?

Oxygen content should not affect the binding of propidium iodide and SYTO 9 to nucleic acids. SYTO 9 will label all cells, and propidium iodide will label only dead cells or cells with a compromised membrane.

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I have a LIVE/DEAD BacLight Bacterial Viability kit that has SYTO 9 and propidium iodide in it. Will I be able to stain eukaryotic cells that have engulfed bacteria and determine if the bacteria are alive or dead using this kit?

Unfortunately, no. SYTO 9 will label the nuclei of live or dead cells, including the eukaryotic cells. Propidium iodide is cell impermeant, and will only enter dead cells. If the eukaryotic cells are dead, they will label with propidium iodide as well. If the eukaryotic cells are alive, propidium iodide will not be able to enter and thus will not label the bacteria inside, whether the bacteria are alive or dead. We are not aware of any way to do a viability assay of bacteria once they have been engulfed by cells.

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How do I prepare dead cell controls for LIVE/DEAD cell viability assays?

There are two easy options. One is to heat-inactivate the cells by placing at 60 degrees C for 20 minutes. The second is to subject the cells to 70% ethanol. Alcohol-fixed cells can be stored indefinitely in the freezer until use, potentially up to several years.

Centrifuge cells, pellet, and remove supernatant.
Fix cells: Add 10 mL ice cold 70% ETOH to a 15 mL tube containing the cell pellet, adding dropwise at first while vortexing, mix well.
Store in freezer until use.
When ready to use, wash twice and resuspend in buffer of choice.

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What bacterial parameters can I look at by flow cytometry?

You can stain bacteria with a general stain such as BacLight Green Bacterial Stain (Cat. No. B35000) or BacLight Red Bacterial Stain (Cat. No. B35001). You can look at gram character (Cat. No. L7005), cell viability (Cat. Nos. L7007, L7012, and L13152), cell count (Cat. Nos. L34856 and B7277), and cell vitality. Cell vitality can be measured by membrane potential (Cat. No. B34950) or by metabolism (Cat. Nos. B34954 and B34956).

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Can I look at bacteria and yeast on a flow cytometer?

Yes, you can. We offer:

-Counting assays: Bacteria Counting Kit, for flow cytometry (Cat. No. B7277) or LIVE/DEAD BacLight Bacterial Viability and Counting Kit, for flow cytometry (Cat. No. L34856).
-Viability/vitality assays: LIVE/DEAD BacLight Bacterial Viability Kit (Cat. No. L13152).
-Membrane potential: BacLight Bacterial Membrane Potential Kit (Cat. No. B34950).
-Yeast viability/vitality assays: LIVE/DEAD FungaLight Yeast Viability Kit, for flow cytometry (Cat. No. L34952), FungaLight Yeast CFDA, AM/Propidium Iodide Vitality Kit (Cat. No. F34953)

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.