The agar concentration must be high enough to prevent liquefaction but not so high that it inhibits growth.
The purpose of culturing microorganisms is to isolate, identify, count, preserve, or grow them.
Bacteria
A type of microorganism
Bacterial multiplication
1. If they have enough nutrients and are in a suitable temperature, they can multiply once every 20 minutes
2. After one hour a single bacterium could have reproduced to give 8 bacteria
3. They undergo simple cell division known as binary fission
Bacteria and other microorganisms
Can be grown in a lab
Can be grown in a nutrient broth solution or as colonies on an agar gel plate
Need certain conditions to flourish
Culturing microorganisms
1. Use cultures of microorganisms to investigate the action of disinfectants and antibiotics
2. Precautions must be taken to stop unwanted microorganisms growing as well
Culturing microorganisms on agar jelly in a petri dish
1. Hot agar jelly is poured into petri dishes
2. An inoculating loop is used to transfer the microorganism onto the agar jelly
3. The inoculating loop must be sterilized first by passing it across a hot flame
4. The petri dish must have a lid on it always to ensure unwanted contamination doesn't occur
5. The lid should be taped on to prevent any accidental removal and stored upside down
Growth medium
The agar jelly
Microorganisms need carbohydrates for energy and mineral ions
They may also need extra proteins and vitamins
Bacteria grow and reproduce more quickly
When they are warm
In labs and schools, the microorganisms are usually kept at about 25 degrees Celsius as this is a safe temperature, although 37 degrees Celsius would be better
