Monochrome Staining – Comprehensive Guide | Principle, Procedure and Result | Biologyideas.com

What is Monochrome Staining?

• Monochrome staining can be achieved by staining the cell rather than staining the background of the cell.
• The principle of Monochrome staining is based on the principle of producing a marked contrast between the bacterial sample and its surrounding, with the help of staining with a basic stain.
• Monochrome staining can be used to observe the morphology of cells in pure culture as well as for observing different morphotypes in any sample.
• Monochrome staining is also known as Simple Staining.
• Most bacteria contain acidic material distributed more or less uniformly throughout the cell. They, therefore, stain with basic dyes.
• Sample stains are used to detect the shape, arrangement, and relative size of bacteria.

What is Differential Staining?

• This staining procedure utilizes more than one stain and differentiates organisms on the basis of the stain that they retain.
• The importance of such a staining procedure is that by staining the cells one can differentiate the cells into different types, which is often needed for the identification of the cells.
• The commonly used differential staining procedures are Gram staining and acid-fast staining.

Requirements

1. Saline suspension of the sample
2. Microincinerator or Bunsen burner
3. Inoculating loop
4. Staining tray
5. Microscope
6. Lens paper
7. Bibulous (highly absorbent) paper
8. Glass slides

Stains and Chemicals for Monochrome staining

1. Crystal violet – 0.5%
2. Methylene Blue – 1%
3. Malachite green – 0.5%
4. Safranin – 1%
5. Neutral red – 1%

Procedure of Monochrome Staining

1. Place a slide on the staining tray.
2. Sterilize the wire loop and pick up a loopful of culture suspension and prepare a smear on the clean slide.
3. Air dry and gently pass through the flame to heat fix the smear.
4. Place a slide on the staining stand.
5. Add 1% crystal violet or any suitable stain so as to cover the smear.
6. Wait for 2-3 minutes.
7. Gently wash the slide with tap water.
8. Air dry and observe under oil immersion lens.

Observation and result of Monochrome staining

Fig. Some Common Shapes of Bacteria

Fig. Result of Monochrome Staining

Just observe the final bacterial sample under the microscope.

Observe and note the morphology of the bacterial sample (Shape, Colour) in the notebook.

Bacilli and diplobacilli – Rod-shaped bacteria, purple
Spirilla – spiral-shaped bacteria, purple
Cocci – spherical-shaped, bacteria, purple

Bacterial Sample	Shape	Colour
Bacilli and Diplobacilli	Rod	purple
Spirilla	Spiral	purple
Cocci	Spherical	purple

Reference and Sources

• https://courses.lumenlearning.com/microbiology/chapter/staining-microscopic-specimens
• https://en.wikipedia.org/wiki/Gram_stain
• https://www.microblife.in/what-is-simple-staining/
• https://microbenotes.com/simple-staining-principle-procedure-and-result-interpretation

Further Readings

1. Acid fast staining of bacteria
2. Algae
3. Aseptic Transfer Technique
4. Bacterial Flagella, Fimbriae and Pili
5. Bacterial Growth and Nutrition
6. Extremophiles
7. Fimbriae vs Flagella
8. Fimbriae vs Pili
9. Fundamental Microscopy
10. Growth Curve of Bacteria
11. Instruments used in Microbiology Laboratory
12. MacConkey agar
13. McFarland Standards
14. Negative Staining
15. Nutritional Requirements of Micro-Organisms
16. Preparation and Sterilization of Culture Media
17. Serial Dilution in Microbiology
18. Spread Plate Technique
19. Streak Plate Technique

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