1. Where can we find bacteria?

2. How can you find bacteria?
You can’t see it, so how do you find it?
Under the right conditions, bacteria grows very fast, exponentially
Some bacteria populations can double every 10 minutes
Bacteria grow in colonies – a colony is a visible mass of bacterial growth on solid medium that developed from 1 or a few cells
A colony can contain millions of cells
We can find bacteria by growing it in the right conditions until it is visible to the human eye

3. Growing/culturing bacteria
Conditions – temperature, light
Agar – source of nutrients for growth
From Malay word “agar-agar” meaning jelly
Gelatinous substance made from seaweed
Ingredient used in Japanese desserts

4. Lab Today We’ll look for bacteria around the classroom and school
Track your cultures
Infer good conditions for bacterial growth

5. How to Sample Bacteria Get a Petri dish
2 Samples
3 Samples
4 Samples
Get a Petri dish
With a marker, divide it into 2, 3, or 4 equal parts

6. How to Sample Bacteria Write on the bottom side (side with the agar)
Write small and around the edge so you can see the bacteria growing later
Decide where you will sample and label your Petri dish accordingly

7. How to Sample Bacteria Get a sterile swab – don’t touch the cotton end
Swab the area to be tested
Open your Petri dish carefully and swab the cotton in the specified area on the agar
Close the Petri dish quickly
Get a new swab for each sample
When done, close the Petri dish and use scotch tape to seal the sides
Put the Petri dish upside down in a dark, warm place

8. Photo Credits
Slide 1 (Title): and
Slide 3: and masak-masak.blogspot.com/ 2007_09_01_archive.html
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