Culturing microorganisms

Bacteria multiply by simple cell division (binary fission) as often as once every 20 minutes if they have enough nutrients and a suitable temperature. Bacteria can be grown on an agar gel plate, uncontaminated cultures of microorganism are required for investigating the action of disinfectants and antibiotics.

Aseptic Technique + Required Practical

All equipment must be sterilised before use

1. A Petri dish with agar is heated to 150 c for 50 minutes, then cooled

2. Pass the inoculating loop through the flame of a Bunsen burner. - remove any impurities

3. Dip the inoculating loop into the bacteria culture

4. Only lift the lid of the agar plate slightly - let as little bacteria in as possible

5. Petri dish kept at 25 c for 48 hrs

To calculate zone of inhibition use $\pi r^2$