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Be confident you're getting a great value with this complete, 5-star-rated kit that is used to differentiate bacteria using the Gram staining method. It includes Hucker's crystal violet, safranin counterstain, Gram's iodine stain, ethyl alcohol, 12 plain microscope slides, 100 coverslips, a medicine dropper, non-latex gloves, and our own, well-reviewed study guide.
Want to use this kit for a science fair project? See our experiment ideas below to get you started.
Test different types of bacteria, such as Gram-positive Bacillus cereus and Gram-negative Rhodospirillum rubrum and compare how the stains differ. (Or just order this bacteria culture comparison set.)
What is Gram staining? Hans Christian Gram, a Danish bacteriologist, discovered that bacteria could be divided into two different groups - one that retained a stain ("gram-positive") and one that didn't ("gram-negative"). His method for identifying these two groups became the first step in any bacterial identification process.
Gram's method of staining has several steps: a sample of bacteria is placed on a microscope slide, then is stained and "fixed" with iodine. The slide is then washed in a solvent to "decolorize" the first stain. Gram-positive cells will retain the stain even after being washed in the solvent, but the stain will be removed from the gram-negative cells. This is because the cell walls of gram-negative cells contain more lipids (fatty substances). The solvent dissolves the lipid layer, allowing the color to be drawn from the cell. The solvent causes the gram-positive cell wall to dehydrate, closing the pores and trapping the stain inside the cell. In the last step, the gram-negative cells are stained a different color, to contrast them from the gram-positive cells.
Science Fair Project Ideas:
Take amazing close-up pictures of the bacteria you see under your microscope! This 3.0 Megapixel Digital Camera is a great deal! It takes high-clarity images and is easy to use.
Shipping Note: This item contains regulated chemicals and only ships Economy or UPS to a street address in the 50 US states.