محلول آیودین گرمز

Gram’s Iodine Solution is a key reagent used in the Gram staining procedure, a method developed by Hans Christian Gram for the differentiation of bacterial species into two main groups: Gram-positive and Gram-negative. It acts as a mordant, helping to fix the crystal violet dye within bacterial cells during the staining process.

🏭⚗️ Production
Gram’s Iodine Solution is typically prepared by dissolving iodine in potassium iodide and water. The most common formulation contains 1g of iodine and 2g of potassium iodide in 100 mL of distilled water. The iodine forms a complex with the crystal violet dye used in the previous step of the Gram stain, thereby helping the dye to bind more strongly to the bacterial cell wall.

🔬 Properties
Gram’s Iodine Solution is a brownish-yellow solution that has the chemical property of forming an iodine-crystal violet complex within bacterial cells. This complex is insoluble in water, which helps retain the purple color of the Gram-positive bacteria after the decolorization step. The iodine itself does not stain the bacteria but enhances the retention of the crystal violet dye, particularly in bacteria with a thick peptidoglycan layer.

🧪 Applications
Gram Staining Procedure: The primary application of Gram’s Iodine Solution is in the Gram staining technique for bacterial classification. After the bacterial sample is stained with crystal violet, Gram’s Iodine is added as a mordant to fix the dye inside the cell walls, particularly of Gram-positive bacteria.
Differentiation of Bacteria: In the Gram stain, Gram-positive bacteria retain the crystal violet-iodine complex and appear purple, whereas Gram-negative bacteria do not, and they lose the dye after the decolorization step, requiring a counterstain like safranin to appear red or pink.
Mordanting Agent: In histology and microbiology, Gram’s Iodine is used as a mordant in staining techniques that require the formation of a complex between the dye and the tissue or bacterial cell.