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Microbiology: Dyes for bacteria and yeast

To date, we have not identified a fluorescent cellular stain that will detect bacteria but not mammalian cells with high specificity, or vice versa. While some mammalian cell stains show weak staining of bacteria, they usually do show some signal, and will frequently stain dead bacteria more intensely than live bacteria.

We offer a selection of antibodies for specific bacterial antigens, which potentially have applications for differential staining of bacteria vs. mammalian cells, but we have not validated them in co-culture models.

Also see our Viability PCR Technology Page to learn about how PMA dye can be used for highly specific detection of microbial cell viability in complex samples.

Fixation is not recommended after staining with the Viability/Cytotoxicity Assay Kit (cat. # 30027) as the dead cell dye, EthD-III will transfer to all cells and not maintain dead cell-specific staining. Our Live-or-Dye™ NucFix™ Red (cat. # 32010) is a formaldehyde-fixable dead cell dye that can be used in bacteria.

Viability qPCR (vPCR) can be an alternative strategy for quantitating live and dead bacteria. Using dead cell-specific dyes, PMA (cat. # 40019) or PMAxx (cat. # 40069) that covalently modify DNA (of only dead cells) after photo-crosslinking, a simple quantitative PCR (qPCR) amplification is used to selectively amplify live-cell DNA. Learn more about the vPCR technology.

CellBrite® and MemBrite® Stains were originally developed for staining mammalian cells in culture, but some of the stains also have been validated for other organisms and applications. For dyes to stain yeast or bacteria membranes, see Cellular Stains in Different Organisms. For information on staining other organisms or cell types, please see our Tech Tip: Researching Applications for Membrane Dyes.

The CellBrite® Cytoplasmic Membrane Dyes do not stain bacteria. The reactive CellBrite® Fix dyes stain both gram-positive and gram-negative bacteria, while the MemBrite® Fix dyes stain only gram-positive bacteria. However we have not tested these dyes for cell division tracking in bacteria.

There is literature describing the use of CFSE to track bacterial cell division,  the ViaFluor® SE cell proliferation dyes are likely to work in a similar manner, but we have not tested this.

See our Cellular Stains Table for a comprehensive list of cellular stains with their ability to stain various cell types.

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