FLAGELLA STAINING

• The motility of many bacteria is due to the presence of thread like appendages called flagella.
• Flagella are a thin proteinaceous structure which is originate from cytoplasm and comes out from the cell wall.
• Types of flagellar patterns:
• Monotrichous: single flagellum at one end.
• Lophotrichous: many flagella at one end.
• Amphitrichous: flagella on both ends.
• Peritrichous:  flagella all over the surface.

Principle:

• For staining of flagella, Ziehl’s carbol fuchsin is commonly used.
• Carbol fuchisn is a mixture of basic fuchisn and phenol which has great affinity towards the mycolic acids found in cell membrane of bacteria.
• In addition, the stain contains tannic acid and potassium alum used to coat and thicken the flagellum to make it visible.

Requirements:

• 18 hours old culture of proteus vulgaris
• Flagella mordant
• Ziehl’s carbol fuchsin
• Glass slide
• Dichromate solution
• 95% alcohol
• Distilled water
• Wash bottle
• Inoculating loop

Procedure:

• Take the slide and dip in dichromate solution then wash with water and rinse with 95% alcohol, pass the slide through flame and allow it to cool.
• Prepare the bacterium suspension in distilled water and incubate for 10-15 minutes at room temperature.
• Place a loop full of the sample on one of the edges of the slide.
• Tilt the slide to make the drop spread on the slide and a thin film in prepared.
• Leave the slide to air dry the smear.
• Cover the smear with flagella mordant and leave for 10 minutes.
• Wash the slide with distilled water.
• Flood the carbol fuchsin on the slide and leave for 5 minutes.
• Wash the slide with distilled water.

Results:

• Under the microscope the bacterial cell appear pink with deep stained rod, flagella with pink colour on the outer coat.