Gram Stain Kit

Shipping Note: This item contains regulated chemicals and only ships Economy or Ground to a street address in the 50 US states.

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.

Kit Contents

• Hucker's Crystal violet, 15ml
• Ethyl alcohol, 30 ml
• Gram's Iodine stain, 15ml
• Gram Stain Kit instructions
• Nitrile gloves, pair
• Pipet (medicine dropper)
• Safranin O stain, 15ml
• Slide coverslips
• Plain glass slides, 12/pk

Science Fair Project Ideas:

• Do antibacterial cleaners work more effectively against gram-positive or gram-negative bacteria?
• Are common antibiotics equally effective against both gram-positive and gram-negative bacteria?

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.

More Information

• Product Instructions