4.1.1.6 Culturing microorganisms practical

Why are cultures of microorganisms not kept above 25 degrees celsius?

Because more harmful pathogens are more likely to grow above this temp

What is a culture medium?

Bacteria are cultured in these - they contain the carbohydrates, minerals, proteins and vitamins they need to grow.

What culture medium do we use in this practical?

Agar jelly

How to make an agar plate?

1. Hot agar jelly is poured onto a petri dish.

2. When jelly is cooled, inoculating loops are used to transfer microorganisms.

3. Microorganisms can then multiply.

How to use uncontaminated cultures? (Aseptic techniques)

1. Petri dish and culture medium must be sterilised before use (using high temp)

   1. To kill unwanted microorganisms

2. The inoculating loop can also be sterilised (using high temp)

3. After transferring the bacteria, the lid of the petri dish should be lightly taped on

   1. to stop microorganisms from the air getting in

4. Petri dish should be stored upside down

   1. to stop condensation falling onto the agar plate