Gram Stain Kit 

MCE Gram Stain Kit can be used to differentiate between Gram-negative and Gram-positive bacteria.

The primary stain is crystal violet, a basic dye taken up by all bacteria due to its ability to rapidly permeate the cell wall. It stains the protoplast of bacteria purple. The potassium-iodine mixture is the mordant which complexes with the primary stain in the cell. Due to their thick cell walls, extensive peptidoglycan layers, and dense crosslinking, Gram-positive bacteria retain the crystal violet-iodine complex inside the cell wall after ethanol decolorization, which makes them appear purple. On the other hand, Gram-negative bacteria have thin cell walls, high lipid content in the outer membrane, and a thin, loosely cross-linked peptidoglycan layer. After decolorization with ethanol, the lipid-rich outer membrane dissolves rapidly, causing the crystal violet-iodine complex to leach out from the thin, loose peptidoglycan network. Therefore, Gram-negative bacteria appear colorless after decolorization and are subsequently counterstained with safranin, which turns them red.

Features of MCE Gram Stain Kit

Ready to use: Liquid reagent is pre-packaged in solution, simple and convenient.

Ease of identification: As it stains the gram positive organisms as purple and gram-negative organisms as red.

Rapid results: 5 - 10 min for the staining.

4°C, 1 year

Keep away from light.

1. It is recommended to select bacterial strains in the active growth phase for staining and testing. Over-cultured Gram-positive bacteria, dead cells, or partially lysed bacteria may result in false negatives.

2. The smear should not be too thick. If it is too thick, incomplete decolorization may occur, leading to false positives. If the smear is thick, it is recommended to extend the decolorization time and wash with water until no purple color remains.

3. The key to Gram staining lies in strictly controlling the degree of decolorization. Over-decolorization may cause Gram-positive bacteria to be misidentified as Gram-negative, while insufficient decolorization may cause Gram-negative bacteria to be misidentified as Gram-positive.

4. If Solution B becomes transparent, the product loses its effectiveness and it is not recommended for use.

5. This product is for R&D use only, not for drug, household, or other uses.

6. For your safety and health, please wear a lab coat and disposable gloves to operate.

1. Smear Fixation: Make a thin smear of the material for study on a glass slide, then dry and fix it.

Note: a. The slide can be air-dried or dried using a slide warmer.

b. Directly pass the slide through the flame 1 - 2 times to fix it. The flame temperature should not be too high.

2. Staining

1) Primary Staining: Add an appropriate amount of Solution A, stain for 1 min and rinse with water.

2) Mordanting: Add an appropriate amount of Solution B, stain for 1 min and rinse with water.

3) Decolorization: Add an appropriate amount of Solution C, gently shake the slide, and decolorize based on the thickness of the smear (30 s - 1 min), rinse with water and blot dry.

4) Counterstaining: Add an appropriate amount of Solution D, stain for 1 min and rinse with water.

5) After blotting dry or air-drying, examine under an oil immersion lens.

Note: When washing with water, perform the action gently. Rinse the slide along the diagonal direction using a wash bottle to avoid washing off the bacteria.

3. Results Observation

Gram-positive bacteria: Purple.

Gram-negative bacteria: Red.

1. It is recommended to select bacterial strains in the active growth phase for staining and testing. Over-cultured Gram-positive bacteria, dead cells, or partially lysed bacteria may result in false negatives.

2. The smear should not be too thick. If it is too thick, incomplete decolorization may occur, leading to false positives. If the smear is thick, it is recommended to extend the decolorization time and wash with water until no purple color remains.

3. The key to Gram staining lies in strictly controlling the degree of decolorization. Over-decolorization may cause Gram-positive bacteria to be misidentified as Gram-negative, while insufficient decolorization may cause Gram-negative bacteria to be misidentified as Gram-positive.

4. If Solution B becomes transparent, the product loses its effectiveness and it is not recommended for use.

5. This product is for R&D use only, not for drug, household, or other uses.

6. For your safety and health, please wear a lab coat and disposable gloves to operate.