Moeller staining involves the use of a steamed dye
reagent in order to increase the stainability of
endospores
An endospore is a dormancy, dormant, tough, and non-reproductive structure produced by some bacteria in the phylum Bacillota. The name "endospore" is suggestive of a spore or seed-like form (''endo'' means 'within'), but it is not a true spore ...
.
Carbol fuchsin
Carbol fuchsin, carbol-fuchsin, carbolfuchsin, or Castellani's paint (CAS ) is a mixture of phenol and basic fuchsin that is used in bacterial staining procedures. It is commonly used in the staining of mycobacteria because it has an affinity fo ...
is the primary stain used in this method. Endospores are stained red, while the
counterstain
A counterstain is a stain with colour contrasting to the principal stain, making the stained structure easily visible using a microscope.
Examples include the malachite green counterstain to the fuchsine stain in the Gimenez staining technique ...
methylene blue stains the vegetative bacteria blue.
Endospores are surrounded by a highly resistant spore coat, which is highly resistant to excessive heat, freezing,
desiccation, as well as chemical agents. More importantly, for identification, spores are resistant to commonly employed staining techniques; therefore alternative staining methods are required.
Method
Carbol fuchsin is applied to a heat-fixed slide. The slide is then heated over a bunsen burner, or suspended over a hot water bath, covered with a paper towel, and steamed for 3 minutes. The slide is rinsed with acidified ethanol, and counter-stained with
Methylene blue. An improved method involves the addition of the surfactant
Tergitol 7 to the carbol fuchsin stain, and the omission of the steaming step.
See also
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Schaeffer–Fulton stain
The Schaeffer–Fulton stain is a technique designed to isolate endospores by staining any present endospores green, and any other bacterial bodies red. The primary stain is malachite green, and the counterstain is safranin, which dyes any other b ...
Further reading
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References
Microbiology techniques
Staining
Bacteriology
Microscopy
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