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Biology LibreTexts

20: Flagella Stain

Objectives

  • Identify flagella on bacterial cells.
  • Differentiate among different types of flagellation.

The basic point about the flagella stain is that the combination of chemicals produces a thickened coat around the flagella, making them more easily seen with a light microscope. Flagella are extremely thin and of small diameter, so they are below the resolution of the light microscope if unstained. 

We will not be making our own flagella stains for a variety of reasons:

  • producing a good flagella is rather like making good art
  • flagella are very delicate and tend to break off the cells easily when manipulated
  • environmental factors such as temperature, pH, age of culture can affect the stability of the flagella (notice that lots of cells have lost their flagella)

Categories of flagellation 

  • monotrichous = single flagellum
  • peritrichous = flagella all around
  • amphitrichous = flagella at both ends
  • lophotrichous = tuft of many flagella at one end or both ends
  • atrichous = without flagella, nonmotile

Motility

Motility can be identified in a couple of different ways:

  • the hanging drop wet mount
  • motility agar media (SIM and tetrazolium motility agars used later)

MATERIALS NEEDED

  • prepared flagella stains (there are different types of flagellation in the slide boxes)

THE PROCEDURE

  1. These stains are bought and ready to use.
  2. Although they have cover slips, you still use oil when on 100X magnification.
  3. Be sure to remove the oil with the lens paper.

INTERPRETATION

You should see different kinds of flagellation on the various slides:

  • monotrichous
  • peritrichous
  • atrichous
  • amphitrichous
  • lophotrichous

 

        

Various flagellation Images

QUESTIONS

  1. Draw an example of an amphitrichously flagellated bacillus-shaped bacterium.
  2. What designation does one used for a bacterium without flagella?

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