Iodine is added as a mordant to enhance crystal violet staining by forming a crystal violet-iodine complex.
The primary stain used in Gram staining is crystal violet.
The mordant used in the process of gram staining is called crystal violet.
If the iodine in the Gram's stain was omitted, the crystal violet which enters the cell will not be able to form the Crystal Violet Iodine (CVI) complex. The CVI complex molecule has a larger size than that of Crystal violet molecule and hence Gram +ve bacteria are able to retain the stain. If iodine were omitted, even Gram+ve cells would get decolorised by Alcohol treatment and would be seen as Gram-ve cells.
safranin
One common method to distinguish between different types of bacteria is Gram staining. This method involves staining bacteria with crystal violet and iodine, followed by a decolorization step and counterstain. Based on whether bacteria retain the stain (Gram-positive) or not (Gram-negative), they can be differentiated.
No, iodine is not a basic stain. Iodine is commonly used in Gram staining to identify bacteria as either Gram-positive or Gram-negative based on their cell wall composition. It acts as a mordant in the staining process and helps to fix the crystal violet stain in Gram staining.
Lugol's Iodine = 20g Potassium Iodide + 10g Iodine dissolved in 1L H2O Gram's Iodine = 6.7g potassium iodide + 3.3g Iodine dissolved in 1L H2O Recipe's taken from Flinn Scientific Catalog I have on campus. Looks to me as Gram's is just a dilute version of Lugol's. Same ratio of KI:I just less of it. Couldn't tell you much about differences in application however.
Iodine is used as a mordant in the gram staining procedure to make large crystals when it is used with crystal violet dye. In gram positive cell walls those crystals get stuck and wont get washed off with the alcohol. In gram negative cell walls the crystals are washed out.
Gram positive cells will appear pink if iodine is not used in the Gram staining process. This is because without iodine, the crystal violet stain is not retained by the thick peptidoglycan layer of the cell wall in Gram positive bacteria.
Crystal violet iodine complex is a chemical compound formed when crystal violet dye interacts with iodine. This complex is commonly used in microbiology as a stain for bacterial cells, allowing them to be visualized under a microscope. The crystal violet iodine complex binds to the peptidoglycan layer of bacterial cell walls, imparting a purple color to the cells.
Iodine is used in Gram staining to form a complex with crystal violet, which helps to trap the dye within the cell wall of Gram-positive bacteria. This step is important in differentiating between Gram-positive and Gram-negative bacteria based on their ability to retain the crystal violet dye.
iodine& grams iodine Gram's iodine is a solution of 2% iodine and 3% potassium iodide in 70% ethanol. Gram's iodine is also used as a forensic toxicology reagent for the detection of alkaloids, as a source of iodine for iodometric titrations, as an indicator for the presence of starch, and as a general laboratory source of iodine/iodide. This solution is laboratory grade, and not for medicinal use. Iodine is non metallic,dark gray,lustrous,solid element
The primary stain used in Gram staining is crystal violet.
The mordant used in the process of gram staining is called crystal violet.
If the iodine in the Gram's stain was omitted, the crystal violet which enters the cell will not be able to form the Crystal Violet Iodine (CVI) complex. The CVI complex molecule has a larger size than that of Crystal violet molecule and hence Gram +ve bacteria are able to retain the stain. If iodine were omitted, even Gram+ve cells would get decolorised by Alcohol treatment and would be seen as Gram-ve cells.
as a couterstain
Thomas Francis McNamara has written: 'Iodine and the quantitative gram reaction' -- subject(s): Iodine, Stains and staining (Microscopy)