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Thermo Scientific™ Gram Stain Kit

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Differentiate gram-positive organisms from gram-negative organisms using Thermo Scientific™ Remel™ Gram Stain Kit. The Gram stain method was developed in 1884 by the Danish bacteriologist, Christian Gram, to differentiate bacterial cells from infected tissue1. Later it was discovered that the bacterial cell wall composition was the key to the Gram stain and would differentiate bacteria into two groups based on cell color after staining. Since that time there have been many modifications of the original technique2,3.

Use of gram staining kit helps in differentiating gram-positive organisms from gram-negative organisms.

Ready-to-use: Liquid reagents supplied in 250mL bottles

Ease of identification: As it stains the gram positive organisms as purple and gram-negative organisms as red.

Rapid results: 5-10 mins for the staining.

The gram staining kit consists of 4 bottles containing 250 mL of Gram Crystal Violet, Safranin, Gram Iodine and Gram Decolorizer each.

Crystal Violet, a basic dye, is the primary stain taken up by all bacteria due to its ability to rapidly permeate the cell wall. It stains the protoplast of bacteria purple. The potassium-iodine mixture, in gram iodine, is the mordant which complexes with the primary stain in the cell. In gram-positive cells, the crystal violet-iodine complex is trapped in the cell due to a decrease in cell wall permeability caused by alcohol dehydration. Gram-positive cells are stained purple.

In gram-negative cells, the complex is removed by the Decolorizer due to an increase in permeability caused by solubility of the lipids in alcohol.

The counterstain used must be a contrasting color to the primary stain and, in this case, it is Safranin which stains gram-negative cells red.

Not all products are available for sale in all territories. Please inquire.

Remel™ and Oxoid™ products are now part of the Thermo Scientific brand.


Volume (Metric)

4 x 250 mL




Crystal Violet; Decolorizer; Iodine; Safranin; plastic tray




CE Marked