Motility test- Hanging drop technique

MOTILITY TEST

HANGING DROP TECHNIQUE:

AIM:

 To observe the bacterial motility by following hanging drop technique

PRINCIPLE:

Hanging drop preparation is a special type of wet mount (in which a drop of medium containing the organisms is placed on a microscope slide), often is used in dark illumination to observe the motility of bacteria.

Hanging Drop Method Preparation

In this method a drop of culture is placed on a cover slip that is encircled with petroleum jelly (or any other sticky material). The cover slip and drop are then inverted over the well of a depression slide. The drop hangs from the cover slip, and the petroleum jelly forms a seal that prevents evaporation. This preparation gives good views of microbial motility.

 Materials required:

1.      Glass slides (glass slide with depression) or Normal glass slide with adhesive or paraffin ring, Paraffin wax, Loop, Coverslip, Microscope, Bunsen burner

2.      Young broth culture of motile bacteria (e.g. Proteus mirabilis)

Procedure:

1.      Take a clean glass cavity slide and hold a clean coverslip by its edges and carefully dab Vaseline on its corners using a toothpick.

2.      Place a loopful of the broth culture to be tested in the center of the coverslip.

3.      Turn the concavity slide upside down (concavity down) over the drop on the coverslip so that the vaseline seals the coverslip to the slide around the concavity.

4.      Turn the slide over so the coverslip is on top and the drop can be observed hanging from the coverslip over the concavity.

5.      Place the preparation in the microscope slide holder and align it using the naked eye so an edge of the drop is under the low power objectives.

6.      Observe the slide and Focus the edge of the drop carefully in the microscope.

Result: The movement of bacteria was observed under the 40x objective with optimum light background.