Simple Staining Technique for Bacterial Culture

Purpose

• Objective: To examine the size, shape, and arrangement of bacterial specimens using a simple staining method.

Organism

• Bacteria Used: Staphylococcus

Equipment and Materials

• Clean microscope slide
• China marking pencil
• Bunsen burner
• Inoculating loop
• Distilled water
• Safranin dye
• Bibulus paper
• Microscope with oil immersion capability

Procedure

Preparing the Slide

1. Label the Slide
   • Use a china marking pencil to label one end of the slide with the specimen name.
   • Draw a circle in the center of the slide (size of a nickel).
2. Preparing for Sample Application
   • Turn the slide so the circle is on the bottom.
   • Add a drop of distilled water onto the slide.

Transferring Bacteria

3. Sterilize the Inoculating Loop
   • Pass the loop through the Bunsen burner flame.
   • Allow the loop to cool.
4. Transfer the Bacteria
   • Touch the bacterial colony with the cooled loop.
   • Mix the bacteria with water on the slide, spreading the mixture to fill the circle.
5. Dry the Slide
   • Air dry at room temperature until a thin white haze appears.

Staining and Observation

6. Heat Fixing
   • Pass the slide through a flame three times to heat fix.
7. Staining with Safranin
   • Flood the circle with safranin dye for 30 seconds.
8. Washing and Drying
   • Rinse the slide gently with distilled water.
   • Drain excess water and blot dry with Bibulus paper.
   • Air dry completely.

Microscopic Examination

9. Load Slide onto Microscope
   • Begin with the lowest power objective.
   • Use coarse and fine adjustments for focusing.
10. Observing Under Oil Immersion
    • Use oil immersion lens for bacterial observation.
    • Staphylococcus will appear as small red balls.

Documentation

• Sketch: Draw the observed image in your lab notebook.

Conclusion

• The simple stain technique makes bacterial cells visible and identifiable under a microscope, highlighting their shape and arrangement.