PROCEDURE: First prepare a smear, Take a clean grease free slide, and add a few

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PROCEDURE: First prepare a smear, Take a clean grease free slide, and add a few drops of distilled water on it. Next heat the inoculated loop to sterilized it by sticking it in the flame of the Bunsen burner (let it cool down). Then take the inoculating loop in the tube that contains the bacterium (Staphylococcus aureus) to get a few amount to placed it into the slide. After placing the bacterium and the water spreading the contents on the slide, take the inoculating loop and sterilized it again by sticking it into the flame of the Bunsen burner, let the slide to air dry. Then stain, flood the contents with crystal violet thoroughly and let it still for one to two minutes. Then, rinse the slide in distilled water and apply few drops of lodine on the slide. Next, rinse with distilled water and then with ethanol and rinse the slide in distilled water again. Finally, add a few drops of Safranin on the slide and keep it for one or two minutes and rinse it again with the distilled water CONCLUSION: Gram staining is an auxiliary process used in microscopic techniques used to enhance the clarity of the microscopic image. Stains and dyes are widely used in the scientific field to highlight the structure of the biological specimens, cells, tissues etc. Gram stain is a staining technique that differentiates bacteria into two groups: gram positive and gram negative. The procedure is based on the ability of microorganisms to retain color of the stains used during the gram stain reaction. Gram negative bacteria are decolorized by the alcohol, losing the color of the primary stain, purple. Gram negative bacteria are not decolorized by alcohol and will remain as purple. Therefore, the objective of this laboratory experiment was accomplished. Through the lens of the microscope number 1, I was able to distinguish the form, size, and color of the bacteria (Staphylococcus aureus), however could not focused since the microscope did not focused properly Paraphrase the procedure and conclusion

Explanation / Answer

Smear preparation :

Gram Staining

Conclusion:

The Gram staining technique is the most important and widely used microbiological differential staining technique. This differential staining procedure separates most bacteria into two groups on the basis of cell wall composition

When the bacteria is stained with primary stain Crystal Violet and fixed by the mordant, some of the bacteria are able to retain the primary stain and some are decolorized by alcohol. The cell walls of gram positive bacteria have a thick layer of protein-sugar complexes called peptidoglycan and lipid content is low. Decolorizing the cell causes this thick cell wall to dehydrate and shrink, which closes the pores in the cell wall and prevents the stain from exiting the cell. So the ethanol cannot remove the Crystal Violet-Iodine complex that is bound to the thick layer of peptidoglycan of gram positive bacteria and appears blue or purple in colour.

In case of gram negative bacteria, cell wall also takes up the CV-Iodine complex but due to the thin layer of peptidoglycan and thick outer layer which is formed of lipids, CV-Iodine complex gets washed off. When they are exposed to alcohol, decolorizer dissolves the lipids in the cell walls, which allows the crystal violet-iodine complex to leach out of the cells. Then when again stained with safranin, they take the stain and appears red in color. The aim of the this laboratory experiment was accomplished

I was able to distinguish the form, size and colour of the bacteria (Staphylococcus aureus), however, could not focused since the microscope did not focused properly

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