check the motility of the given culture of bacteria.

A very small drop of bacteria suspension is hung from the centre of a cover slip into the cavity of a cavity slide. The hanging drop is observed under a microscope using oil-immersion objective. If the bacteria are motile, its cells can be seen to have erratic movement in the surrounding medium.

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.

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

Adjust the light using the diaphragm lever to maximise the visibility of the cells.Observe the cells noting their morphology and grouping and determine whether true motility can be observed.

Brownian movement should be visible on slides of all the organisms, but there should also show true motility.

Wash the depression slide and after soaking in lysol buckets or discard the prepared glass slide