Motility testing of the microorganism or hanging drop preparation:-
Requirements:-
1. Hollow ground (depression) or cavity slide
2. Coverslip
3. Petroleum jelly
4. Two known cultures (one containing motile and other non-motile organism)
5. Microscope
Procedure–
1. Apply petroleum jelly at the four corners of the coverslip.
2. Place aseptically loopful of culture at the middle of the coverslip.
3. Take the cavity slide and invert the concave portion over the drop.
4. Invert the whole preparation so that the coverslip is on the top.
5. Examine the suspension under low power lens first. Cut down the light by adjusting the diaphragm of the condenser and then swing the objectives to the high dry lens,
6. Observe for motility (it can be detected by the presence of directional motion).
Note–
1. Look at one organism for about 1 minute and see if it moves out of its original position.
2. Jumping or dancing organisms are not necessarily true motiles, but these movements may be due to Brownian movement.
3. Record the results of the observations by indicating “motile” or “non-motile” organism. After finishing the observations, place the cavity slide in disinfectant solution.