Gram stain - Wikipedia
Lugol's iodine solution is always added after addition of crystal violet to form a stable complex with crystal violet that strengthen the bonds of the stain with the cell wall. [4] Gram staining is almost always the first step in the identification of a bacterial group.
1.10: Gram Stain - Biology LibreTexts
The Gram stain uses four stains/reagents: crystal violet, Gram's iodine, ethanol, and safranin. Crystal violet (the primary stain), enters the peptidoglycan of all bacteria giving them a purple color. The next stain is Gram’s iodine, the mordant, which combines with the crystal violet to make a bigger complex in the peptidoglycan wall. The ...
7: Gram Stains - Biology LibreTexts
Dec 21, 2024 · In the gram stain, two dyes are used, crystal violet and safranin. Crystal violet is first applied to the bacterial smear, staining all cells. This first step, if no other steps were completed, would be a simple stain! However, in the Gram stain, the stained smear is then treated with Gram’s iodine.
Gram Staining- Principle, Reagents, Procedure, Steps, Results
Feb 4, 2022 · When Gram’s Iodine is added as mordant, the iodine (I – or I-3 ion) interacts with CV + ion and forms CV-I complex within cytoplasm and cell membrane and cell wall layers. When decolorizing solution (ethanol or a mixture of ethanol and acetone) is …
Gram Stain: Identifying Differences in Bacterial Cell Walls
Next, Gram’s iodine, a mordant, is added. A mordant is a substance used to set or stabilize stains or dyes; in this case, Gram’s iodine acts like a trapping agent that complexes with the crystal violet, making the crystal violet–iodine complex clump and stay contained in thick layers of peptidoglycan in the cell walls.
Why iodine is used in staining? - ScienceOxygen
Sep 12, 2022 · Iodine is a mordant in the Gram stain technique, which functions to intensify the primary stain. A student creates a Gram stain on a bacterial specimen that has a mix of gram-negative and gram-positive organisms but accidentally forgets the decolorizer step.
1.13: Gram Stain - Biology LibreTexts
Mar 14, 2024 · Next, Gram’siodine, a mordant, is added. A mordant is a substance used to set or stabilize stains or dyes; in this case, Gram’s iodine acts like a trapping agent that complexes with the crystal violet, making the crystal violet–iodine complex clump and stay contained in thick layers of peptidoglycan in the cell walls.
GRAM STAINING: Introduction, principles, materials, procedure, …
Aug 15, 2024 · Principle of Gram staining. The first step in Gram staining is covering the smear with a primary stain crystal violet. Then the stain is fixed with a mordant, Lugol’s iodine, which forms a complex with the primary stain. This will prevent it from washing off easily.
What's the role of iodine in the Gram stain procedure?
Mar 22, 2023 · Iodine forms the crystal violet-iodine complex in order for dye to easily be removed. Iodine fixes the crystal violet into the cell call of bacteria by acting as a chemical mordant. G+ bacteria remain purple due to their adherence to the iodine.
Gram Iodine PVP is a mordant which complexes with the crystal violet in the protoplast of bacterial cells. In gram-positive bacteria, the crystal violet-iodine complex is retained due to decreased cell wall permeability. In gram-negative cells, the complex is removed by the decolorizer due to an increase in the cell wall permeability.