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Motility Test for Bacteria Hanging Drop Method

In this motility test for bacteria hanging drop method post we have briefly explained motility test principle, objectives, requirements, procedure, uses and limitations of hanging drop method in microbiology.

Hanging Drop Method in Microbiology

Hanging drop method in microbiology is mostly used to investigate bacterial movement. The form, relative size, and arrangement of bacteria, protozoan parasites, sperm motility, and faeces inspection are also useful analysis done by hanging drop method in microbiology.

The phrase “hanging drop” of hanging drop method in microbiology is self-explanatory; the drop hangs from the coverslip after preparation. Bacteria can travel around freely thanks to the hanging drop. Unlike wet mount, where mobility is limited to a thin coating in hanging drop method in microbiology.

Principle

A very small drop of bacteria suspension is dropped into the cavity of a cavity slide from the centre of a cover slip during hanging drop method in microbiology. A microscope with an oil-immersion objective is used to examine the hanging drop. If the bacteria are motile, the surrounding media will show erratic movement of the organism’s cells.

Reagents

Young broth culture

Clean cavity slide

Clean cover slip

Vaseline

Spirit lamp

Wire loop

Compound microscope

Procedure

Hanging Drop Method

Cavity slide with hanging drop

1. Apply a small amount of Vaseline to the corners of a clean cover slip. Using a sterile wire loop, place a drop of broth culture in the centre of the cover slip.

2. Invert a clean cavity slide, concavity facing the drop, gently over the cover slip (i.e. downwards) Make sure the drop does not come into contact with the slide.

3. Turn the slide over quickly and gently. The coverslip should be on top, and the drop should be suspended from the coverslip.

4. Reduce the light by lowering the sub stage condenser. If required, shut the iris diaphragm partially. Focus the drop under a low-power objective so that the drop’s edge is exactly in the minuscule field’s centre.

5. Switch to a high-power objective and focus on the drop’s edge. Examine the creatures’ movement, morphology, relative size, and organisation in hanging drop method in microbiology.

Hanging Drop Method

Hanging drop preparation

Results

1. A positive hanging drop method in microbiology is directional intentional motility. Motile organisms move around in relation to one another.

2. Brownian movement (random jiggling or shaking caused by molecular bombardment) should not be confused with genuine motility, in which the organisms remain in the same relative location to each other.

3. Darting motility is seen in Campylobacter and Vibrio cholerae, and it appears as tiny dots darting in and out of the field in hanging drop method in microbiology.

Motile Bacilli

Salmonella

Vibrio cholerae

Pseudomonas

Proteus

Non-motile

Bacilli

Klebsiella

Shigella

Clostridium welchii

Haemophilus influenzae

Further Readings

Reference