In the Gram stain, is there any replacement for primary stain, secondary stain, decolourizer and mordant? What results will the replacements produce?

I found that crystal violet can be replaced with methylene blue but in that case, what will the secondary stain, mordant etc. be? Please also explain what result we might get.


1 Answer 1


As you may have realized, crystal violet can be replaced by a lot of dyes since the ethanol will wash out the dye from the gram negative cells. Methylene blue is a nice choice - malachite green may also work.

A weak concentration of hydrochloric acid (3%) is also a possible replacement for the ethanol. A 3% HCl solution is used in the acid-fast stain but it may be too strong for non-acid fast cells. It would be worth testing it out and trying it to see if it could replace the ethanol step.

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    – tyersome
    Mar 23, 2021 at 19:51

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